Detailed Description
The invention is further described with reference to the following examples.
Example 1: as shown in fig. 1-3, the high-efficiency road sprinkler comprises a sprinkler and an engine connected with the sprinkler, wherein the engine is used for driving the sprinkler and comprises a power part, an oil injection system and a hydraulic part, the power part comprises an air inlet check valve 9, a power piston 10, a combustion chamber 11, an oil injector 12, a scavenging port 13, a return piston 15 and a compression piston 19, the hydraulic part comprises a compression cavity 1, a pump cavity 7, a return cavity 14 and a hydraulic loop, the compression cavity 1 is arranged at the rear part of the engine and is provided with a first oil port 5 and a second oil port 6, the first oil port 5 and the second oil port 6 are respectively connected with a compression accumulator 4 through a first control valve 3 and a second control valve 2, the pump cavity 7 is respectively connected with a low-pressure oil path 26 and a high-pressure oil path 25 through the check valve 9, the high-pressure oil path 25 is used for supplying oil to the engine, a return control valve 17 and a low-pressure energy accumulator 18 are arranged on the low-pressure oil way 26, and an oil return check valve 21 is arranged on the return control valve 17 in a bypass manner; the return cavity 14 is directly connected with the high-pressure energy accumulator 8, and an oil pipeline from the high-pressure energy accumulator 8 to the cylinder body is provided with a pressure reducing valve 22; the compression energy accumulator 4 is communicated with the high-pressure energy accumulator 8 through an oil pipeline, and a starting valve 23 is further arranged on the oil pipeline between the compression energy accumulator 4 and the high-pressure energy accumulator 8; the high-pressure oil way 25 is connected with a load accumulator 24, and a path is led out from the rear of the pressure reducing valve 22 and is connected with the compression accumulator 4; the oil injection system is a high-pressure common-rail type electric control injection system.
The tail end of the engine is provided with a hydraulic balloon 27, the hydraulic balloon 27 is filled with pressure oil which is injected in advance and has certain pressure, the bottom of the hydraulic balloon 27 is connected with the low-pressure energy accumulator 18 through an oil pipeline, and when the load pressure is suddenly reduced or the oil injection quantity is overshot to cause the piston to pass through the second oil port 6 at a higher speed, the hydraulic balloon 27 can play a good buffering role and basically cannot generate a rebound effect; meanwhile, in order to prevent the hydraulic balloon 27 from being broken by overpressure, a spring-type safety valve 28 is arranged between the hydraulic balloon 27 and the low-pressure accumulator 18, once the spring-type safety valve 28 of the overpressure of the hydraulic balloon 27 is automatically opened and the pressure is buffered by the low-pressure accumulator 18, the hydraulic balloon 27 can play a certain role in supplementing a hydraulic system of an engine. The upper left side of the hydraulic balloon 27 is provided with an inclined dead zone oil port 34, the straight line of the inclined dead zone oil port is tangent to the hydraulic balloon 27, the dead zone oil port 34 is connected with the compression energy accumulator 4 through a dead zone return electromagnetic valve 35 arranged between the dead zone oil port 34 and the compression energy accumulator, and under the working condition of fire, when the tail end of the piston assembly is located in a dead zone B between the second oil port 6 and the hydraulic balloon 27, the piston assembly returns to an ideal bottom dead center area A between the second oil port 6 and the first oil port 5 by opening the dead zone return electromagnetic valve 35 to start the next stroke.
The high-pressure accumulator 8 serves for: firstly, when the engine is stopped, the piston assembly can be stopped at the position of the lower dead point, and the creeping is reduced; and secondly, under the starting working condition of the engine and the occurrence of a fire accident, the piston assembly is pushed to return to the position of the bottom dead center, so that the engine can continue to start the next cycle.
The engine also comprises a position detection system, the position detection system detects signals when the piston assembly reaches a top dead center position, a bottom dead center position and a feed-forward position through a linear displacement sensor and a position trigger sensor, the feed-forward position is positioned on one side between the top dead center position and the bottom dead center position and close to the top dead center position and is used for controlling the first control valve 3 to close when a working condition piston compression stroke is started, and the feed-forward position is determined according to the speed value of the piston and matched with the position detection system.
The fuel injection system comprises a high-pressure oil pump 31, a common rail pipe 32, an electric control fuel injector 33, a pressure sensor and an electronic control unit, when the engine works, fuel enters the high-pressure oil pump 31 through a filter 30 under the action of a fuel delivery pump 29, low-pressure oil is changed into high-pressure oil after being compressed by the high-pressure oil pump 31 and is input into the common rail pipe 32 by the high-pressure oil pump 31, in the common rail pipe 32, the electronic control unit receives feedback of the pressure sensor and controls a pressure limiting valve to adjust the pressure value in a rail and keep the pressure value constant, and then the high-pressure oil which is relatively stable and has certain pressure is input into the electric control fuel injector 33 to wait for a fuel injection instruction of the electronic control unit.
The engine is also provided with a constant pressure driving system which mainly comprises the engine and a hydraulic variable motor, and the constant of the output oil pressure is kept through the driving moment of the motor and the load resisting moment. The hydraulic variable motor is driven by output high-pressure oil and is connected with a load through a speed reducer, and the discharge capacity of the hydraulic variable motor is automatically adjusted along with the change of working pressure. The hydraulic variable motor is mechanically connected with a load, and the rotating speeds of the hydraulic variable motor and the load are equal; under the condition of stable operation, the driving torque of the motor is equal to the load resisting torque in opposite directions, and when the resistance is increased, the driving torque of the motor is smaller than the load resisting torque, so that the rotating speed of the motor is reduced. Since the flow rate of the output hydraulic oil is not changed, the flow resistance of the output hydraulic oil increases under the condition of increasing the back pressure, thereby causing the pressure in the system to increase. At this time, the variable mechanism of the hydraulic motor receives the feedback of the pressure increasing signal and adjusts the pressure increasing signal to increase the self-displacement, and the flow of the motor is increased under the condition of reducing the rotating speed, so that the flow resistance of the oil liquid is reduced, and the constant of the output oil liquid pressure of the engine is kept. Meanwhile, as the displacement is increased, the driving torque of the motor is increased and gradually balanced with the load resisting torque, and the system achieves a stable working state again. Similarly, when the load resistance is reduced and the hydraulic motor drive torque is greater than the load resistance torque, the motor speed is increased, causing a reduction in pressure within the hydraulic system. At the moment, the displacement of the hydraulic variable motor is adjusted in the direction of reducing, so that the driving torque and the load resisting torque are balanced, and the pressure in the system is kept constant while the system works stably.
The engine further comprises a starting control system, a normal work control system and a fire-extinguishing control system:
the starting control system is used for controlling the starting condition of the engine: when a starting signal is sent out, the starting valve 23 and the pressure reducing valve 22 are opened, the pressure of the compression energy accumulator 4 is increased due to the communication with the high-pressure energy accumulator 8, and the compression ratio of the engine is improved; the engine control unit detects signals of the displacement sensor, if the detection result shows that the piston assembly is at a bottom dead center, the first control valve 3 and the second control valve 2 are opened, the piston assembly starts a compression stroke under the action of the compression energy accumulator 4, if the piston assembly is not at the bottom dead center, the return control valve 17 is firstly opened, hydraulic oil in the pump cavity 7 and the compression cavity 1 is discharged from the low-pressure oil way 26, the piston assembly returns to the bottom dead center under the action of the pressure of the high-pressure energy accumulator 8, the return control valve 17 is closed, and then the compression stroke is started; when the speed of the piston is reduced to a certain set value, the piston is considered to reach a feedforward position, the second control valve 2 is closed at the moment, after the piston reaches a top dead center, the first control valve 3 is closed, and the return control valve 17 is opened, so that the control mode of closing the first control valve 3 and the second control valve 2 step by step not only ensures the speed of a compression stroke, but also reduces the resistance of an expansion stroke; and after the piston assembly returns to the bottom dead center again, closing the return control valve 17, completing a working cycle by the piston assembly, recording the pressure and temperature values in the cylinder when the piston assembly reaches the top dead center in the process, judging whether the cylinder pressure and temperature recorded in the previous cycle meet the ignition condition of the diesel oil or not when the opening signal of the second control valve 2 is sent again, and repeating the working process until the pressure and temperature meet the ignition condition and then starting to enter the control process of normal working if the pressure and temperature in the cylinder are lower.
And the normal work control system is used for controlling the normal working condition of the engine: after the engine enters a normal working condition, the starting valve 23 and the pressure reducing valve 22 are closed, the first control valve 3 is kept in a normally open state, after a starting signal is sent, the second control valve 2 is opened, hydraulic oil in the compression energy accumulator 4 firstly enters the compression cavity 1 through the second control valve 2 to push the piston assembly to move towards a top dead center, after the first oil port 5 is opened, the second control valve 2 is closed, the compression cavity 1 is communicated with the compression energy accumulator 4 through the first oil port 5, when the piston assembly reaches an oil injection position, a sensor is triggered to generate an oil injection signal, the oil injection quantity is controlled to enable the ratio of compression time and expansion time to be equal to the ratio of volume changes of two strokes of a hydraulic pump, so that the expansion flow and the compression flow are basically equal to reduce the output flow pulsation of the engine, the fuel injection process is completed through an oil injection system, the fuel burns to release heat near the top dead center, and the piston assembly returns to, and stabilizes at bottom dead center before the second control valve 2 opens again.
The misfire control system is used for controlling the misfire condition of the engine: in the working process of the engine, after a starting signal is sent out, the position of the piston assembly is detected once, if the frequency and the frequency change rate of the engine are both smaller than set values, the position of the piston assembly is detected, if the piston assembly is not at the bottom dead center position and the cylinder temperature and cylinder pressure are smaller than a misfire value, the engine is considered to be on fire in the previous cycle, at the moment, the first control valve 3 is closed, the pressure reducing valve 22 and the repositioning control valve 17 are opened, the piston assembly is repositioned to the bottom dead center position, then the first control valve 3 is opened, the next starting pulse signal is waited, and the engine moves according to the normal working cycle.
The second control valve 2 adopts a high-frequency electro-hydraulic servo valve with the maximum flow rate of 250L/min and the opening pulse width of 10ms, the electro-hydraulic servo valve is a hydraulic control valve which receives an analog quantity electric control signal, outputs the change along with the size and the polarity of the electric control signal and has quick dynamic response and good static characteristics, such as: high resolution, small hysteresis, good linearity, etc. When the electro-hydraulic servo valve with the maximum flow rate of 250L/min and the opening pulse width of 10ms is used, the length of the acceleration section of the piston assembly is increased to about 5 times of the original length, and the time used for the compression stroke is obviously reduced, so that the motion period is reduced by nearly 7ms compared with the original length, the maximum working frequency of the engine is obviously improved, and an unexpected effect is achieved.
Example 2: as shown in fig. 1-3, the high-efficiency road sprinkler comprises a sprinkler and an engine connected with the sprinkler, wherein the engine is used for driving the sprinkler and comprises a power part, an oil injection system and a hydraulic part, the power part comprises an air inlet check valve 9, a power piston 10, a combustion chamber 11, an oil injector 12, a scavenging port 13, a return piston 15 and a compression piston 19, the hydraulic part comprises a compression cavity 1, a pump cavity 7, a return cavity 14 and a hydraulic loop, the compression cavity 1 is arranged at the rear part of the engine and is provided with a first oil port 5 and a second oil port 6, the first oil port 5 and the second oil port 6 are respectively connected with a compression accumulator 4 through a first control valve 3 and a second control valve 2, the pump cavity 7 is respectively connected with a low-pressure oil path 26 and a high-pressure oil path 25 through the check valve 9, the high-pressure oil path 25 is used for supplying oil to the engine, a return control valve 17 and a low-pressure energy accumulator 18 are arranged on the low-pressure oil way 26, and an oil return check valve 21 is arranged on the return control valve 17 in a bypass manner; the return cavity 14 is directly connected with the high-pressure energy accumulator 8, and an oil pipeline from the high-pressure energy accumulator 8 to the cylinder body is provided with a pressure reducing valve 22; the compression energy accumulator 4 is communicated with the high-pressure energy accumulator 8 through an oil pipeline, and a starting valve 23 is further arranged on the oil pipeline between the compression energy accumulator 4 and the high-pressure energy accumulator 8; the high-pressure oil way 25 is connected with a load accumulator 24, and a path is led out from the rear of the pressure reducing valve 22 and is connected with the compression accumulator 4; the oil injection system is a high-pressure common-rail type electric control injection system.
The tail end of the engine is provided with a hydraulic balloon 27, the hydraulic balloon 27 is filled with pressure oil which is injected in advance and has certain pressure, the bottom of the hydraulic balloon 27 is connected with the low-pressure energy accumulator 18 through an oil pipeline, and when the load pressure is suddenly reduced or the oil injection quantity is overshot to cause the piston to pass through the second oil port 6 at a higher speed, the hydraulic balloon 27 can play a good buffering role and basically cannot generate a rebound effect; meanwhile, in order to prevent the hydraulic balloon 27 from being broken by overpressure, a spring-type safety valve 28 is arranged between the hydraulic balloon 27 and the low-pressure accumulator 18, once the spring-type safety valve 28 of the overpressure of the hydraulic balloon 27 is automatically opened and the pressure is buffered by the low-pressure accumulator 18, the hydraulic balloon 27 can play a certain role in supplementing a hydraulic system of an engine. The upper left side of the hydraulic balloon 27 is provided with an inclined dead zone oil port 34, the straight line of the inclined dead zone oil port is tangent to the hydraulic balloon 27, the dead zone oil port 34 is connected with the compression energy accumulator 4 through a dead zone return electromagnetic valve 35 arranged between the dead zone oil port 34 and the compression energy accumulator, and under the working condition of fire, when the tail end of the piston assembly is located in a dead zone B between the second oil port 6 and the hydraulic balloon 27, the piston assembly returns to an ideal bottom dead center area A between the second oil port 6 and the first oil port 5 by opening the dead zone return electromagnetic valve 35 to start the next stroke.
The high-pressure accumulator 8 serves for: firstly, when the engine is stopped, the piston assembly can be stopped at the position of the lower dead point, and the creeping is reduced; and secondly, under the starting working condition of the engine and the occurrence of a fire accident, the piston assembly is pushed to return to the position of the bottom dead center, so that the engine can continue to start the next cycle.
The engine also comprises a position detection system, the position detection system detects signals when the piston assembly reaches a top dead center position, a bottom dead center position and a feed-forward position through a linear displacement sensor and a position trigger sensor, the feed-forward position is positioned on one side between the top dead center position and the bottom dead center position and close to the top dead center position and is used for controlling the first control valve 3 to close when a working condition piston compression stroke is started, and the feed-forward position is determined according to the speed value of the piston and matched with the position detection system.
The fuel injection system comprises a high-pressure oil pump 31, a common rail pipe 32, an electric control fuel injector 33, a pressure sensor and an electronic control unit, when the engine works, fuel enters the high-pressure oil pump 31 through a filter 30 under the action of a fuel delivery pump 29, low-pressure oil is changed into high-pressure oil after being compressed by the high-pressure oil pump 31 and is input into the common rail pipe 32 by the high-pressure oil pump 31, in the common rail pipe 32, the electronic control unit receives feedback of the pressure sensor and controls a pressure limiting valve to adjust the pressure value in a rail and keep the pressure value constant, and then the high-pressure oil which is relatively stable and has certain pressure is input into the electric control fuel injector 33 to wait for a fuel injection instruction of the electronic control unit.
The engine is also provided with a constant pressure driving system which mainly comprises the engine and a hydraulic variable motor, and the constant of the output oil pressure is kept through the driving moment of the motor and the load resisting moment. The hydraulic variable motor is driven by output high-pressure oil and is connected with a load through a speed reducer, and the discharge capacity of the hydraulic variable motor is automatically adjusted along with the change of working pressure. The hydraulic variable motor is mechanically connected with a load, and the rotating speeds of the hydraulic variable motor and the load are equal; under the condition of stable operation, the driving torque of the motor is equal to the load resisting torque in opposite directions, and when the resistance is increased, the driving torque of the motor is smaller than the load resisting torque, so that the rotating speed of the motor is reduced. Since the flow rate of the output hydraulic oil is not changed, the flow resistance of the output hydraulic oil increases under the condition of increasing the back pressure, thereby causing the pressure in the system to increase. At this time, the variable mechanism of the hydraulic motor receives the feedback of the pressure increasing signal and adjusts the pressure increasing signal to increase the self-displacement, and the flow of the motor is increased under the condition of reducing the rotating speed, so that the flow resistance of the oil liquid is reduced, and the constant of the output oil liquid pressure of the engine is kept. Meanwhile, as the displacement is increased, the driving torque of the motor is increased and gradually balanced with the load resisting torque, and the system achieves a stable working state again. Similarly, when the load resistance is reduced and the hydraulic motor drive torque is greater than the load resistance torque, the motor speed is increased, causing a reduction in pressure within the hydraulic system. At the moment, the displacement of the hydraulic variable motor is adjusted in the direction of reducing, so that the driving torque and the load resisting torque are balanced, and the pressure in the system is kept constant while the system works stably.
The engine further comprises a starting control system, a normal work control system and a fire-extinguishing control system:
the starting control system is used for controlling the starting condition of the engine: when a starting signal is sent out, the starting valve 23 and the pressure reducing valve 22 are opened, the pressure of the compression energy accumulator 4 is increased due to the communication with the high-pressure energy accumulator 8, and the compression ratio of the engine is improved; the engine control unit detects signals of the displacement sensor, if the detection result shows that the piston assembly is at a bottom dead center, the first control valve 3 and the second control valve 2 are opened, the piston assembly starts a compression stroke under the action of the compression energy accumulator 4, if the piston assembly is not at the bottom dead center, the return control valve 17 is firstly opened, hydraulic oil in the pump cavity 7 and the compression cavity 1 is discharged from the low-pressure oil way 26, the piston assembly returns to the bottom dead center under the action of the pressure of the high-pressure energy accumulator 8, the return control valve 17 is closed, and then the compression stroke is started; when the speed of the piston is reduced to a certain set value, the piston is considered to reach a feedforward position, the second control valve 2 is closed at the moment, after the piston reaches a top dead center, the first control valve 3 is closed, and the return control valve 17 is opened, so that the control mode of closing the first control valve 3 and the second control valve 2 step by step not only ensures the speed of a compression stroke, but also reduces the resistance of an expansion stroke; and after the piston assembly returns to the bottom dead center again, closing the return control valve 17, completing a working cycle by the piston assembly, recording the pressure and temperature values in the cylinder when the piston assembly reaches the top dead center in the process, judging whether the cylinder pressure and temperature recorded in the previous cycle meet the ignition condition of the diesel oil or not when the opening signal of the second control valve 2 is sent again, and repeating the working process until the pressure and temperature meet the ignition condition and then starting to enter the control process of normal working if the pressure and temperature in the cylinder are lower.
And the normal work control system is used for controlling the normal working condition of the engine: after the engine enters a normal working condition, the starting valve 23 and the pressure reducing valve 22 are closed, the first control valve 3 is kept in a normally open state, after a starting signal is sent, the second control valve 2 is opened, hydraulic oil in the compression energy accumulator 4 firstly enters the compression cavity 1 through the second control valve 2 to push the piston assembly to move towards a top dead center, after the first oil port 5 is opened, the second control valve 2 is closed, the compression cavity 1 is communicated with the compression energy accumulator 4 through the first oil port 5, when the piston assembly reaches an oil injection position, a sensor is triggered to generate an oil injection signal, the oil injection quantity is controlled to enable the ratio of compression time and expansion time to be equal to the ratio of volume changes of two strokes of a hydraulic pump, so that the expansion flow and the compression flow are basically equal to reduce the output flow pulsation of the engine, the fuel injection process is completed through an oil injection system, the fuel burns to release heat near the top dead center, and the piston assembly returns to, and stabilizes at bottom dead center before the second control valve 2 opens again.
The misfire control system is used for controlling the misfire condition of the engine: in the working process of the engine, after a starting signal is sent out, the position of the piston assembly is detected once, if the frequency and the frequency change rate of the engine are both smaller than set values, the position of the piston assembly is detected, if the piston assembly is not at the bottom dead center position and the cylinder temperature and cylinder pressure are smaller than a misfire value, the engine is considered to be on fire in the previous cycle, at the moment, the first control valve 3 is closed, the pressure reducing valve 22 and the repositioning control valve 17 are opened, the piston assembly is repositioned to the bottom dead center position, then the first control valve 3 is opened, the next starting pulse signal is waited, and the engine moves according to the normal working cycle.
The second control valve 2 adopts a high-frequency electro-hydraulic servo valve with the maximum flow of 200L/min and the opening pulse width of 15ms, the electro-hydraulic servo valve is a hydraulic control valve which receives an analog quantity electric control signal, outputs the change along with the size and the polarity of the electric control signal and has quick dynamic response and good static characteristics, such as: high resolution, small hysteresis, good linearity, etc. When the electro-hydraulic servo valve with the maximum flow rate of 200L/min and the opening pulse width of 15ms is used, the length of the acceleration section of the piston assembly is increased to about 6 times of the original length, and the time for the compression stroke is obviously reduced, so that the motion period is reduced by nearly 10ms compared with the original length, the maximum working frequency of the engine is obviously improved, and an unexpected effect is achieved.
Example 3: as shown in fig. 1-3, the high-efficiency road sprinkler comprises a sprinkler and an engine connected with the sprinkler, wherein the engine is used for driving the sprinkler and comprises a power part, an oil injection system and a hydraulic part, the power part comprises an air inlet check valve 9, a power piston 10, a combustion chamber 11, an oil injector 12, a scavenging port 13, a return piston 15 and a compression piston 19, the hydraulic part comprises a compression cavity 1, a pump cavity 7, a return cavity 14 and a hydraulic loop, the compression cavity 1 is arranged at the rear part of the engine and is provided with a first oil port 5 and a second oil port 6, the first oil port 5 and the second oil port 6 are respectively connected with a compression accumulator 4 through a first control valve 3 and a second control valve 2, the pump cavity 7 is respectively connected with a low-pressure oil path 26 and a high-pressure oil path 25 through the check valve 9, the high-pressure oil path 25 is used for supplying oil to the engine, a return control valve 17 and a low-pressure energy accumulator 18 are arranged on the low-pressure oil way 26, and an oil return check valve 21 is arranged on the return control valve 17 in a bypass manner; the return cavity 14 is directly connected with the high-pressure energy accumulator 8, and an oil pipeline from the high-pressure energy accumulator 8 to the cylinder body is provided with a pressure reducing valve 22; the compression energy accumulator 4 is communicated with the high-pressure energy accumulator 8 through an oil pipeline, and a starting valve 23 is further arranged on the oil pipeline between the compression energy accumulator 4 and the high-pressure energy accumulator 8; the high-pressure oil way 25 is connected with a load accumulator 24, and a path is led out from the rear of the pressure reducing valve 22 and is connected with the compression accumulator 4; the oil injection system is a high-pressure common-rail type electric control injection system.
The tail end of the engine is provided with a hydraulic balloon 27, the hydraulic balloon 27 is filled with pressure oil which is injected in advance and has certain pressure, the bottom of the hydraulic balloon 27 is connected with the low-pressure energy accumulator 18 through an oil pipeline, and when the load pressure is suddenly reduced or the oil injection quantity is overshot to cause the piston to pass through the second oil port 6 at a higher speed, the hydraulic balloon 27 can play a good buffering role and basically cannot generate a rebound effect; meanwhile, in order to prevent the hydraulic balloon 27 from being broken by overpressure, a spring-type safety valve 28 is arranged between the hydraulic balloon 27 and the low-pressure accumulator 18, once the spring-type safety valve 28 of the overpressure of the hydraulic balloon 27 is automatically opened and the pressure is buffered by the low-pressure accumulator 18, the hydraulic balloon 27 can play a certain role in supplementing a hydraulic system of an engine. The upper left side of the hydraulic balloon 27 is provided with an inclined dead zone oil port 34, the straight line of the inclined dead zone oil port is tangent to the hydraulic balloon 27, the dead zone oil port 34 is connected with the compression energy accumulator 4 through a dead zone return electromagnetic valve 35 arranged between the dead zone oil port 34 and the compression energy accumulator, and under the working condition of fire, when the tail end of the piston assembly is located in a dead zone B between the second oil port 6 and the hydraulic balloon 27, the piston assembly returns to an ideal bottom dead center area A between the second oil port 6 and the first oil port 5 by opening the dead zone return electromagnetic valve 35 to start the next stroke.
The high-pressure accumulator 8 serves for: firstly, when the engine is stopped, the piston assembly can be stopped at the position of the lower dead point, and the creeping is reduced; and secondly, under the starting working condition of the engine and the occurrence of a fire accident, the piston assembly is pushed to return to the position of the bottom dead center, so that the engine can continue to start the next cycle.
The engine also comprises a position detection system, the position detection system detects signals when the piston assembly reaches a top dead center position, a bottom dead center position and a feed-forward position through a linear displacement sensor and a position trigger sensor, the feed-forward position is positioned on one side between the top dead center position and the bottom dead center position and close to the top dead center position and is used for controlling the first control valve 3 to close when a working condition piston compression stroke is started, and the feed-forward position is determined according to the speed value of the piston and matched with the position detection system.
The fuel injection system comprises a high-pressure oil pump 31, a common rail pipe 32, an electric control fuel injector 33, a pressure sensor and an electronic control unit, when the engine works, fuel enters the high-pressure oil pump 31 through a filter 30 under the action of a fuel delivery pump 29, low-pressure oil is changed into high-pressure oil after being compressed by the high-pressure oil pump 31 and is input into the common rail pipe 32 by the high-pressure oil pump 31, in the common rail pipe 32, the electronic control unit receives feedback of the pressure sensor and controls a pressure limiting valve to adjust the pressure value in a rail and keep the pressure value constant, and then the high-pressure oil which is relatively stable and has certain pressure is input into the electric control fuel injector 33 to wait for a fuel injection instruction of the electronic control unit.
The engine is also provided with a constant pressure driving system which mainly comprises the engine and a hydraulic variable motor, and the constant of the output oil pressure is kept through the driving moment of the motor and the load resisting moment. The hydraulic variable motor is driven by output high-pressure oil and is connected with a load through a speed reducer, and the discharge capacity of the hydraulic variable motor is automatically adjusted along with the change of working pressure. The hydraulic variable motor is mechanically connected with a load, and the rotating speeds of the hydraulic variable motor and the load are equal; under the condition of stable operation, the driving torque of the motor is equal to the load resisting torque in opposite directions, and when the resistance is increased, the driving torque of the motor is smaller than the load resisting torque, so that the rotating speed of the motor is reduced. Since the flow rate of the output hydraulic oil is not changed, the flow resistance of the output hydraulic oil increases under the condition of increasing the back pressure, thereby causing the pressure in the system to increase. At this time, the variable mechanism of the hydraulic motor receives the feedback of the pressure increasing signal and adjusts the pressure increasing signal to increase the self-displacement, and the flow of the motor is increased under the condition of reducing the rotating speed, so that the flow resistance of the oil liquid is reduced, and the constant of the output oil liquid pressure of the engine is kept. Meanwhile, as the displacement is increased, the driving torque of the motor is increased and gradually balanced with the load resisting torque, and the system achieves a stable working state again. Similarly, when the load resistance is reduced and the hydraulic motor drive torque is greater than the load resistance torque, the motor speed is increased, causing a reduction in pressure within the hydraulic system. At the moment, the displacement of the hydraulic variable motor is adjusted in the direction of reducing, so that the driving torque and the load resisting torque are balanced, and the pressure in the system is kept constant while the system works stably.
The engine further comprises a starting control system, a normal work control system and a fire-extinguishing control system:
the starting control system is used for controlling the starting condition of the engine: when a starting signal is sent out, the starting valve 23 and the pressure reducing valve 22 are opened, the pressure of the compression energy accumulator 4 is increased due to the communication with the high-pressure energy accumulator 8, and the compression ratio of the engine is improved; the engine control unit detects signals of the displacement sensor, if the detection result shows that the piston assembly is at a bottom dead center, the first control valve 3 and the second control valve 2 are opened, the piston assembly starts a compression stroke under the action of the compression energy accumulator 4, if the piston assembly is not at the bottom dead center, the return control valve 17 is firstly opened, hydraulic oil in the pump cavity 7 and the compression cavity 1 is discharged from the low-pressure oil way 26, the piston assembly returns to the bottom dead center under the action of the pressure of the high-pressure energy accumulator 8, the return control valve 17 is closed, and then the compression stroke is started; when the speed of the piston is reduced to a certain set value, the piston is considered to reach a feedforward position, the second control valve 2 is closed at the moment, after the piston reaches a top dead center, the first control valve 3 is closed, and the return control valve 17 is opened, so that the control mode of closing the first control valve 3 and the second control valve 2 step by step not only ensures the speed of a compression stroke, but also reduces the resistance of an expansion stroke; and after the piston assembly returns to the bottom dead center again, closing the return control valve 17, completing a working cycle by the piston assembly, recording the pressure and temperature values in the cylinder when the piston assembly reaches the top dead center in the process, judging whether the cylinder pressure and temperature recorded in the previous cycle meet the ignition condition of the diesel oil or not when the opening signal of the second control valve 2 is sent again, and repeating the working process until the pressure and temperature meet the ignition condition and then starting to enter the control process of normal working if the pressure and temperature in the cylinder are lower.
And the normal work control system is used for controlling the normal working condition of the engine: after the engine enters a normal working condition, the starting valve 23 and the pressure reducing valve 22 are closed, the first control valve 3 is kept in a normally open state, after a starting signal is sent, the second control valve 2 is opened, hydraulic oil in the compression energy accumulator 4 firstly enters the compression cavity 1 through the second control valve 2 to push the piston assembly to move towards a top dead center, after the first oil port 5 is opened, the second control valve 2 is closed, the compression cavity 1 is communicated with the compression energy accumulator 4 through the first oil port 5, when the piston assembly reaches an oil injection position, a sensor is triggered to generate an oil injection signal, the oil injection quantity is controlled to enable the ratio of compression time and expansion time to be equal to the ratio of volume changes of two strokes of a hydraulic pump, so that the expansion flow and the compression flow are basically equal to reduce the output flow pulsation of the engine, the fuel injection process is completed through an oil injection system, the fuel burns to release heat near the top dead center, and the piston assembly returns to, and stabilizes at bottom dead center before the second control valve 2 opens again.
The misfire control system is used for controlling the misfire condition of the engine: in the working process of the engine, after a starting signal is sent out, the position of the piston assembly is detected once, if the frequency and the frequency change rate of the engine are both smaller than set values, the position of the piston assembly is detected, if the piston assembly is not at the bottom dead center position and the cylinder temperature and cylinder pressure are smaller than a misfire value, the engine is considered to be on fire in the previous cycle, at the moment, the first control valve 3 is closed, the pressure reducing valve 22 and the repositioning control valve 17 are opened, the piston assembly is repositioned to the bottom dead center position, then the first control valve 3 is opened, the next starting pulse signal is waited, and the engine moves according to the normal working cycle.
The second control valve 2 adopts a high-frequency electro-hydraulic servo valve with the maximum flow of 220L/min and the opening pulse width of 20ms, the electro-hydraulic servo valve is a hydraulic control valve which receives an analog quantity electric control signal, outputs the change along with the size and the polarity of the electric control signal and has quick dynamic response and good static characteristics, such as: high resolution, small hysteresis, good linearity, etc. When the electro-hydraulic servo valve with the maximum flow rate of 220L/min and the opening pulse width of 20ms is used, the length of the acceleration section of the piston assembly is increased to about 7 times of the original length, and the time for the compression stroke is obviously reduced, so that the motion period is reduced by nearly 12ms compared with the original length, the maximum working frequency of the engine is obviously improved, and an unexpected effect is achieved.
Example 4: as shown in fig. 1-3, the high-efficiency road sprinkler comprises a sprinkler and an engine connected with the sprinkler, wherein the engine is used for driving the sprinkler and comprises a power part, an oil injection system and a hydraulic part, the power part comprises an air inlet check valve 9, a power piston 10, a combustion chamber 11, an oil injector 12, a scavenging port 13, a return piston 15 and a compression piston 19, the hydraulic part comprises a compression cavity 1, a pump cavity 7, a return cavity 14 and a hydraulic loop, the compression cavity 1 is arranged at the rear part of the engine and is provided with a first oil port 5 and a second oil port 6, the first oil port 5 and the second oil port 6 are respectively connected with a compression accumulator 4 through a first control valve 3 and a second control valve 2, the pump cavity 7 is respectively connected with a low-pressure oil path 26 and a high-pressure oil path 25 through the check valve 9, the high-pressure oil path 25 is used for supplying oil to the engine, a return control valve 17 and a low-pressure energy accumulator 18 are arranged on the low-pressure oil way 26, and an oil return check valve 21 is arranged on the return control valve 17 in a bypass manner; the return cavity 14 is directly connected with the high-pressure energy accumulator 8, and an oil pipeline from the high-pressure energy accumulator 8 to the cylinder body is provided with a pressure reducing valve 22; the compression energy accumulator 4 is communicated with the high-pressure energy accumulator 8 through an oil pipeline, and a starting valve 23 is further arranged on the oil pipeline between the compression energy accumulator 4 and the high-pressure energy accumulator 8; the high-pressure oil way 25 is connected with a load accumulator 24, and a path is led out from the rear of the pressure reducing valve 22 and is connected with the compression accumulator 4; the oil injection system is a high-pressure common-rail type electric control injection system.
The tail end of the engine is provided with a hydraulic balloon 27, the hydraulic balloon 27 is filled with pressure oil which is injected in advance and has certain pressure, the bottom of the hydraulic balloon 27 is connected with the low-pressure energy accumulator 18 through an oil pipeline, and when the load pressure is suddenly reduced or the oil injection quantity is overshot to cause the piston to pass through the second oil port 6 at a higher speed, the hydraulic balloon 27 can play a good buffering role and basically cannot generate a rebound effect; meanwhile, in order to prevent the hydraulic balloon 27 from being broken by overpressure, a spring-type safety valve 28 is arranged between the hydraulic balloon 27 and the low-pressure accumulator 18, once the spring-type safety valve 28 of the overpressure of the hydraulic balloon 27 is automatically opened and the pressure is buffered by the low-pressure accumulator 18, the hydraulic balloon 27 can play a certain role in supplementing a hydraulic system of an engine. The upper left side of the hydraulic balloon 27 is provided with an inclined dead zone oil port 34, the straight line of the inclined dead zone oil port is tangent to the hydraulic balloon 27, the dead zone oil port 34 is connected with the compression energy accumulator 4 through a dead zone return electromagnetic valve 35 arranged between the dead zone oil port 34 and the compression energy accumulator, and under the working condition of fire, when the tail end of the piston assembly is located in a dead zone B between the second oil port 6 and the hydraulic balloon 27, the piston assembly returns to an ideal bottom dead center area A between the second oil port 6 and the first oil port 5 by opening the dead zone return electromagnetic valve 35 to start the next stroke.
The high-pressure accumulator 8 serves for: firstly, when the engine is stopped, the piston assembly can be stopped at the position of the lower dead point, and the creeping is reduced; and secondly, under the starting working condition of the engine and the occurrence of a fire accident, the piston assembly is pushed to return to the position of the bottom dead center, so that the engine can continue to start the next cycle.
The engine also comprises a position detection system, the position detection system detects signals when the piston assembly reaches a top dead center position, a bottom dead center position and a feed-forward position through a linear displacement sensor and a position trigger sensor, the feed-forward position is positioned on one side between the top dead center position and the bottom dead center position and close to the top dead center position and is used for controlling the first control valve 3 to close when a working condition piston compression stroke is started, and the feed-forward position is determined according to the speed value of the piston and matched with the position detection system.
The fuel injection system comprises a high-pressure oil pump 31, a common rail pipe 32, an electric control fuel injector 33, a pressure sensor and an electronic control unit, when the engine works, fuel enters the high-pressure oil pump 31 through a filter 30 under the action of a fuel delivery pump 29, low-pressure oil is changed into high-pressure oil after being compressed by the high-pressure oil pump 31 and is input into the common rail pipe 32 by the high-pressure oil pump 31, in the common rail pipe 32, the electronic control unit receives feedback of the pressure sensor and controls a pressure limiting valve to adjust the pressure value in a rail and keep the pressure value constant, and then the high-pressure oil which is relatively stable and has certain pressure is input into the electric control fuel injector 33 to wait for a fuel injection instruction of the electronic control unit.
The engine is also provided with a constant pressure driving system which mainly comprises the engine and a hydraulic variable motor, and the constant of the output oil pressure is kept through the driving moment of the motor and the load resisting moment. The hydraulic variable motor is driven by output high-pressure oil and is connected with a load through a speed reducer, and the discharge capacity of the hydraulic variable motor is automatically adjusted along with the change of working pressure. The hydraulic variable motor is mechanically connected with a load, and the rotating speeds of the hydraulic variable motor and the load are equal; under the condition of stable operation, the driving torque of the motor is equal to the load resisting torque in opposite directions, and when the resistance is increased, the driving torque of the motor is smaller than the load resisting torque, so that the rotating speed of the motor is reduced. Since the flow rate of the output hydraulic oil is not changed, the flow resistance of the output hydraulic oil increases under the condition of increasing the back pressure, thereby causing the pressure in the system to increase. At this time, the variable mechanism of the hydraulic motor receives the feedback of the pressure increasing signal and adjusts the pressure increasing signal to increase the self-displacement, and the flow of the motor is increased under the condition of reducing the rotating speed, so that the flow resistance of the oil liquid is reduced, and the constant of the output oil liquid pressure of the engine is kept. Meanwhile, as the displacement is increased, the driving torque of the motor is increased and gradually balanced with the load resisting torque, and the system achieves a stable working state again. Similarly, when the load resistance is reduced and the hydraulic motor drive torque is greater than the load resistance torque, the motor speed is increased, causing a reduction in pressure within the hydraulic system. At the moment, the displacement of the hydraulic variable motor is adjusted in the direction of reducing, so that the driving torque and the load resisting torque are balanced, and the pressure in the system is kept constant while the system works stably.
The engine further comprises a starting control system, a normal work control system and a fire-extinguishing control system:
the starting control system is used for controlling the starting condition of the engine: when a starting signal is sent out, the starting valve 23 and the pressure reducing valve 22 are opened, the pressure of the compression energy accumulator 4 is increased due to the communication with the high-pressure energy accumulator 8, and the compression ratio of the engine is improved; the engine control unit detects signals of the displacement sensor, if the detection result shows that the piston assembly is at a bottom dead center, the first control valve 3 and the second control valve 2 are opened, the piston assembly starts a compression stroke under the action of the compression energy accumulator 4, if the piston assembly is not at the bottom dead center, the return control valve 17 is firstly opened, hydraulic oil in the pump cavity 7 and the compression cavity 1 is discharged from the low-pressure oil way 26, the piston assembly returns to the bottom dead center under the action of the pressure of the high-pressure energy accumulator 8, the return control valve 17 is closed, and then the compression stroke is started; when the speed of the piston is reduced to a certain set value, the piston is considered to reach a feedforward position, the second control valve 2 is closed at the moment, after the piston reaches a top dead center, the first control valve 3 is closed, and the return control valve 17 is opened, so that the control mode of closing the first control valve 3 and the second control valve 2 step by step not only ensures the speed of a compression stroke, but also reduces the resistance of an expansion stroke; and after the piston assembly returns to the bottom dead center again, closing the return control valve 17, completing a working cycle by the piston assembly, recording the pressure and temperature values in the cylinder when the piston assembly reaches the top dead center in the process, judging whether the cylinder pressure and temperature recorded in the previous cycle meet the ignition condition of the diesel oil or not when the opening signal of the second control valve 2 is sent again, and repeating the working process until the pressure and temperature meet the ignition condition and then starting to enter the control process of normal working if the pressure and temperature in the cylinder are lower.
And the normal work control system is used for controlling the normal working condition of the engine: after the engine enters a normal working condition, the starting valve 23 and the pressure reducing valve 22 are closed, the first control valve 3 is kept in a normally open state, after a starting signal is sent, the second control valve 2 is opened, hydraulic oil in the compression energy accumulator 4 firstly enters the compression cavity 1 through the second control valve 2 to push the piston assembly to move towards a top dead center, after the first oil port 5 is opened, the second control valve 2 is closed, the compression cavity 1 is communicated with the compression energy accumulator 4 through the first oil port 5, when the piston assembly reaches an oil injection position, a sensor is triggered to generate an oil injection signal, the oil injection quantity is controlled to enable the ratio of compression time and expansion time to be equal to the ratio of volume changes of two strokes of a hydraulic pump, so that the expansion flow and the compression flow are basically equal to reduce the output flow pulsation of the engine, the fuel injection process is completed through an oil injection system, the fuel burns to release heat near the top dead center, and the piston assembly returns to, and stabilizes at bottom dead center before the second control valve 2 opens again.
The misfire control system is used for controlling the misfire condition of the engine: in the working process of the engine, after a starting signal is sent out, the position of the piston assembly is detected once, if the frequency and the frequency change rate of the engine are both smaller than set values, the position of the piston assembly is detected, if the piston assembly is not at the bottom dead center position and the cylinder temperature and cylinder pressure are smaller than a misfire value, the engine is considered to be on fire in the previous cycle, at the moment, the first control valve 3 is closed, the pressure reducing valve 22 and the repositioning control valve 17 are opened, the piston assembly is repositioned to the bottom dead center position, then the first control valve 3 is opened, the next starting pulse signal is waited, and the engine moves according to the normal working cycle.
The second control valve 2 adopts a high-frequency electro-hydraulic servo valve with the maximum flow of 270L/min and the opening pulse width of 25ms, the electro-hydraulic servo valve is a hydraulic control valve which receives an analog quantity electric control signal, outputs the change along with the size and the polarity of the electric control signal and has quick dynamic response and good static characteristics, such as: high resolution, small hysteresis, good linearity, etc. When the electro-hydraulic servo valve with the maximum flow rate of 270L/min and the opening pulse width of 25ms is used, the maximum flow rate of the second control valve 2 is increased to about 7.5 times of the original acceleration segment length of the piston assembly, and the time for a compression stroke is obviously reduced, so that the motion period is reduced by about 12ms compared with the original motion period, the maximum working frequency of the engine is obviously improved, and an unexpected effect is achieved.
Example 5: as shown in fig. 1-3, the high-efficiency road sprinkler comprises a sprinkler and an engine connected with the sprinkler, wherein the engine is used for driving the sprinkler and comprises a power part, an oil injection system and a hydraulic part, the power part comprises an air inlet check valve 9, a power piston 10, a combustion chamber 11, an oil injector 12, a scavenging port 13, a return piston 15 and a compression piston 19, the hydraulic part comprises a compression cavity 1, a pump cavity 7, a return cavity 14 and a hydraulic loop, the compression cavity 1 is arranged at the rear part of the engine and is provided with a first oil port 5 and a second oil port 6, the first oil port 5 and the second oil port 6 are respectively connected with a compression accumulator 4 through a first control valve 3 and a second control valve 2, the pump cavity 7 is respectively connected with a low-pressure oil path 26 and a high-pressure oil path 25 through the check valve 9, the high-pressure oil path 25 is used for supplying oil to the engine, a return control valve 17 and a low-pressure energy accumulator 18 are arranged on the low-pressure oil way 26, and an oil return check valve 21 is arranged on the return control valve 17 in a bypass manner; the return cavity 14 is directly connected with the high-pressure energy accumulator 8, and an oil pipeline from the high-pressure energy accumulator 8 to the cylinder body is provided with a pressure reducing valve 22; the compression energy accumulator 4 is communicated with the high-pressure energy accumulator 8 through an oil pipeline, and a starting valve 23 is further arranged on the oil pipeline between the compression energy accumulator 4 and the high-pressure energy accumulator 8; the high-pressure oil way 25 is connected with a load accumulator 24, and a path is led out from the rear of the pressure reducing valve 22 and is connected with the compression accumulator 4; the oil injection system is a high-pressure common-rail type electric control injection system.
The tail end of the engine is provided with a hydraulic balloon 27, the hydraulic balloon 27 is filled with pressure oil which is injected in advance and has certain pressure, the bottom of the hydraulic balloon 27 is connected with the low-pressure energy accumulator 18 through an oil pipeline, and when the load pressure is suddenly reduced or the oil injection quantity is overshot to cause the piston to pass through the second oil port 6 at a higher speed, the hydraulic balloon 27 can play a good buffering role and basically cannot generate a rebound effect; meanwhile, in order to prevent the hydraulic balloon 27 from being broken by overpressure, a spring-type safety valve 28 is arranged between the hydraulic balloon 27 and the low-pressure accumulator 18, once the spring-type safety valve 28 of the overpressure of the hydraulic balloon 27 is automatically opened and the pressure is buffered by the low-pressure accumulator 18, the hydraulic balloon 27 can play a certain role in supplementing a hydraulic system of an engine. The upper left side of the hydraulic balloon 27 is provided with an inclined dead zone oil port 34, the straight line of the inclined dead zone oil port is tangent to the hydraulic balloon 27, the dead zone oil port 34 is connected with the compression energy accumulator 4 through a dead zone return electromagnetic valve 35 arranged between the dead zone oil port 34 and the compression energy accumulator, and under the working condition of fire, when the tail end of the piston assembly is located in a dead zone B between the second oil port 6 and the hydraulic balloon 27, the piston assembly returns to an ideal bottom dead center area A between the second oil port 6 and the first oil port 5 by opening the dead zone return electromagnetic valve 35 to start the next stroke.
The high-pressure accumulator 8 serves for: firstly, when the engine is stopped, the piston assembly can be stopped at the position of the lower dead point, and the creeping is reduced; and secondly, under the starting working condition of the engine and the occurrence of a fire accident, the piston assembly is pushed to return to the position of the bottom dead center, so that the engine can continue to start the next cycle.
The engine also comprises a position detection system, the position detection system detects signals when the piston assembly reaches a top dead center position, a bottom dead center position and a feed-forward position through a linear displacement sensor and a position trigger sensor, the feed-forward position is positioned on one side between the top dead center position and the bottom dead center position and close to the top dead center position and is used for controlling the first control valve 3 to close when a working condition piston compression stroke is started, and the feed-forward position is determined according to the speed value of the piston and matched with the position detection system.
The fuel injection system comprises a high-pressure oil pump 31, a common rail pipe 32, an electric control fuel injector 33, a pressure sensor and an electronic control unit, when the engine works, fuel enters the high-pressure oil pump 31 through a filter 30 under the action of a fuel delivery pump 29, low-pressure oil is changed into high-pressure oil after being compressed by the high-pressure oil pump 31 and is input into the common rail pipe 32 by the high-pressure oil pump 31, in the common rail pipe 32, the electronic control unit receives feedback of the pressure sensor and controls a pressure limiting valve to adjust the pressure value in a rail and keep the pressure value constant, and then the high-pressure oil which is relatively stable and has certain pressure is input into the electric control fuel injector 33 to wait for a fuel injection instruction of the electronic control unit.
The engine is also provided with a constant pressure driving system which mainly comprises the engine and a hydraulic variable motor, and the constant of the output oil pressure is kept through the driving moment of the motor and the load resisting moment. The hydraulic variable motor is driven by output high-pressure oil and is connected with a load through a speed reducer, and the discharge capacity of the hydraulic variable motor is automatically adjusted along with the change of working pressure. The hydraulic variable motor is mechanically connected with a load, and the rotating speeds of the hydraulic variable motor and the load are equal; under the condition of stable operation, the driving torque of the motor is equal to the load resisting torque in opposite directions, and when the resistance is increased, the driving torque of the motor is smaller than the load resisting torque, so that the rotating speed of the motor is reduced. Since the flow rate of the output hydraulic oil is not changed, the flow resistance of the output hydraulic oil increases under the condition of increasing the back pressure, thereby causing the pressure in the system to increase. At this time, the variable mechanism of the hydraulic motor receives the feedback of the pressure increasing signal and adjusts the pressure increasing signal to increase the self-displacement, and the flow of the motor is increased under the condition of reducing the rotating speed, so that the flow resistance of the oil liquid is reduced, and the constant of the output oil liquid pressure of the engine is kept. Meanwhile, as the displacement is increased, the driving torque of the motor is increased and gradually balanced with the load resisting torque, and the system achieves a stable working state again. Similarly, when the load resistance is reduced and the hydraulic motor drive torque is greater than the load resistance torque, the motor speed is increased, causing a reduction in pressure within the hydraulic system. At the moment, the displacement of the hydraulic variable motor is adjusted in the direction of reducing, so that the driving torque and the load resisting torque are balanced, and the pressure in the system is kept constant while the system works stably.
The engine further comprises a starting control system, a normal work control system and a fire-extinguishing control system:
the starting control system is used for controlling the starting condition of the engine: when a starting signal is sent out, the starting valve 23 and the pressure reducing valve 22 are opened, the pressure of the compression energy accumulator 4 is increased due to the communication with the high-pressure energy accumulator 8, and the compression ratio of the engine is improved; the engine control unit detects signals of the displacement sensor, if the detection result shows that the piston assembly is at a bottom dead center, the first control valve 3 and the second control valve 2 are opened, the piston assembly starts a compression stroke under the action of the compression energy accumulator 4, if the piston assembly is not at the bottom dead center, the return control valve 17 is firstly opened, hydraulic oil in the pump cavity 7 and the compression cavity 1 is discharged from the low-pressure oil way 26, the piston assembly returns to the bottom dead center under the action of the pressure of the high-pressure energy accumulator 8, the return control valve 17 is closed, and then the compression stroke is started; when the speed of the piston is reduced to a certain set value, the piston is considered to reach a feedforward position, the second control valve 2 is closed at the moment, after the piston reaches a top dead center, the first control valve 3 is closed, and the return control valve 17 is opened, so that the control mode of closing the first control valve 3 and the second control valve 2 step by step not only ensures the speed of a compression stroke, but also reduces the resistance of an expansion stroke; and after the piston assembly returns to the bottom dead center again, closing the return control valve 17, completing a working cycle by the piston assembly, recording the pressure and temperature values in the cylinder when the piston assembly reaches the top dead center in the process, judging whether the cylinder pressure and temperature recorded in the previous cycle meet the ignition condition of the diesel oil or not when the opening signal of the second control valve 2 is sent again, and repeating the working process until the pressure and temperature meet the ignition condition and then starting to enter the control process of normal working if the pressure and temperature in the cylinder are lower.
And the normal work control system is used for controlling the normal working condition of the engine: after the engine enters a normal working condition, the starting valve 23 and the pressure reducing valve 22 are closed, the first control valve 3 is kept in a normally open state, after a starting signal is sent, the second control valve 2 is opened, hydraulic oil in the compression energy accumulator 4 firstly enters the compression cavity 1 through the second control valve 2 to push the piston assembly to move towards a top dead center, after the first oil port 5 is opened, the second control valve 2 is closed, the compression cavity 1 is communicated with the compression energy accumulator 4 through the first oil port 5, when the piston assembly reaches an oil injection position, a sensor is triggered to generate an oil injection signal, the oil injection quantity is controlled to enable the ratio of compression time and expansion time to be equal to the ratio of volume changes of two strokes of a hydraulic pump, so that the expansion flow and the compression flow are basically equal to reduce the output flow pulsation of the engine, the fuel injection process is completed through an oil injection system, the fuel burns to release heat near the top dead center, and the piston assembly returns to, and stabilizes at bottom dead center before the second control valve 2 opens again.
The misfire control system is used for controlling the misfire condition of the engine: in the working process of the engine, after a starting signal is sent out, the position of the piston assembly is detected once, if the frequency and the frequency change rate of the engine are both smaller than set values, the position of the piston assembly is detected, if the piston assembly is not at the bottom dead center position and the cylinder temperature and cylinder pressure are smaller than a misfire value, the engine is considered to be on fire in the previous cycle, at the moment, the first control valve 3 is closed, the pressure reducing valve 22 and the repositioning control valve 17 are opened, the piston assembly is repositioned to the bottom dead center position, then the first control valve 3 is opened, the next starting pulse signal is waited, and the engine moves according to the normal working cycle.
The second control valve 2 adopts a high-frequency electro-hydraulic servo valve with the maximum flow rate of 230L/min and the opening pulse width of 30ms, the electro-hydraulic servo valve is a hydraulic control valve which receives an analog quantity electric control signal, outputs the change along with the size and the polarity of the electric control signal and has quick dynamic response and good static characteristics, such as: high resolution, small hysteresis, good linearity, etc. When the electro-hydraulic servo valve with the maximum flow rate of 230L/min and the opening pulse width of 30ms is used, the length of the acceleration section of the piston assembly is increased to about 8 times of the original length, and the time of a compression stroke is obviously reduced, so that the motion period is reduced by nearly 14ms compared with the original length, the maximum working frequency of the engine is obviously improved, and an unexpected effect is achieved.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.