JP3999878B2 - Variable discharge high-pressure pump and common rail fuel injection control apparatus using the variable discharge high-pressure pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable discharge high-pressure pump used to pump and supply a high-pressure fluid in a common-rail fuel injection control device of a diesel engine, for example, and a common rail fuel injection control device using the variable discharge high-pressure pump. .
[0002]
[Prior art]
A common rail fuel injection control device is known as one of fuel injection control devices for diesel engines. The common rail fuel injection control device is provided with a common pressure accumulation pipe (common rail) communicating with each cylinder, and by supplying high pressure fuel at a required flow rate by a variable discharge high pressure pump, the fuel pressure of the common rail ( Common rail pressure) is kept constant. The high-pressure fuel in the common rail is injected into each cylinder by an injector at a predetermined timing (for example, JP-A-64-73166).
[0003]
FIG. 14 shows an example of a variable discharge high-pressure pump used in a common rail fuel injection control device. A plunger 82 driven by a cam (not shown) is reciprocally inserted in a cylinder 81, and the cylinder 81 A pressure chamber 83 is formed by the inner wall surface and the upper end surface of the plunger 82. An electromagnetic valve 84 is attached above the pressure chamber 83, and the electromagnetic valve 84 has a valve body 86 that opens and closes between the low pressure channel 85 and the pressure chamber 83 formed therein.
[0004]
The valve body 86 is in the valve open position in the state shown in the figure where the coil 87 is not energized. When the plunger 82 is lowered, the fuel is supplied from the low-pressure flow path 85 and the valve body 86 around the low-pressure supply pump (feed pump) (not shown). It is introduced into the pressure chamber 83 through a gap. When the coil 87 is energized, the valve body 86 is attracted upward, and its substantially conical tip is seated on the seat portion 88 and closed. At the same time, the fuel in the pressure chamber 83 is pressurized by the ascent of the plunger 82 and is pumped to the common rail (not shown) from the flow path 89 provided on the side wall of the pressure chamber 83.
[0005]
By the way, since the force in the valve closing direction acts on the valve body 86 by the fuel pressure in the pressure chamber 83 while the plunger 82 is raised, once the valve body 86 is closed, the energization to the coil 87 is stopped. Do not open. For this reason, in the variable discharge high pressure pump configured as described above, the pressure feed amount to the common rail is controlled by so-called pre-stroke control that controls the valve closing timing of the valve body 86. That is, after the plunger 82 moves to the ascending stroke, the valve 82 is not closed immediately, the valve opening state is maintained until the fuel in the pressure chamber 83 reaches a predetermined amount, and excess fuel is released to the low pressure flow path 85 side. Thereafter, the valve is closed and pressurization is started, so that a necessary amount of pressurized fluid is pumped to the common rail.
[0006]
However, if the pump oil feed rate increases as the engine speed increases, there arises a problem that the valve body 86 closes (self-closes) regardless of the valve closing signal. This is because when the plunger 82 is lifted, the valve body 86 directly receives the dynamic pressure of the fuel in the pressure chamber 83 at the lower end surface, toward the low pressure flow path 85 from the gap between the valve body 86 and the seat portion 88. This may be due to receiving a force in the valve closing direction due to the throttling effect of the flowing fuel, and the flow rate control may not be performed properly.
[0007]
As countermeasures, it is conceivable to increase the operating stroke of the valve body 86 or to increase the return spring force of the valve body 86. In either case, the valve closing response will be reduced. In order to maintain the valve closing response, it is necessary to increase the electric power supplied to the coil 87 or increase the attraction force of the electromagnetic valve 84 by increasing the physique. There was a problem of inviting.
[0008]
Further, in the variable discharge high pressure pump configured as described above, the flow path to the pressure chamber 83 is opened and closed by the electromagnetic valve 84, and the valve body 86 is seated in response to the valve closing signal until the flow path 85 is closed. Since a certain time is required, this operation response time is usually calculated in advance to control the valve closing timing. However, if the engine speed increases and the pump oil feed rate increases, the opening / closing operation may not be in time, and there is a risk that sufficient control cannot be performed.
[0009]
Therefore, the present inventors can easily and reliably control the amount of pumping to the common rail even when the engine speed increases and the pump oil feed rate is high, and it does not involve an increase in the size of the device or an increase in power. Also, for the purpose of eliminating problems such as response delay due to the use of electromagnetic valves for opening and closing the flow path, the following suction amount metering type variable discharge high pressure pump was proposed (Japanese Patent Application No. 9- No. 100909).
[0010]
In this variable discharge high pressure pump, as shown in FIG. 15, the pressure chamber 91 is formed by the inner wall surface of the cylinder 92 and the upper end surface of the plunger 93, and the plunger 93 moves up and down by the rotation of the cam 94. A check valve 95 that is opened only when suctioning low-pressure fuel into the pressure chamber 91 is provided upstream of the pressure chamber 91, and an electromagnetic valve 96 that controls the flow rate of low-pressure fuel sucked into the pressure chamber 91 is provided upstream thereof. Is provided. While the valve body 961 is open, the electromagnetic valve 96 causes low pressure fuel to flow from the low pressure flow path 97 toward the check valve 95, and the pressure of this fuel opens the valve body 951 of the check valve 95 so that the low pressure fuel is supplied. Is sucked into the pressure chamber 91. Suction is performed at the same suction speed as the descending speed when the cam 94 is lowered, and is terminated by closing the solenoid valve 96. The suction amount is determined by the energization time of the solenoid valve 96. When the cam 94 turns upward and the plunger 93 is pressed, the check valve 95 is closed by the fuel pressure at that time, and the fuel in the pressure chamber 91 is pressurized and fed through the discharge valve 98.
[0011]
Thus, by providing separately the valve body 951 that prohibits the suction of fuel into the pressure chamber 91 during pressure feeding and the valve body 961 that controls the flow rate of the low-pressure fuel sucked into the pressure chamber 91 from the low-pressure channel 97. The problem of self-closing in prestroke control can be solved without increasing the size of the apparatus. Further, by using the check valve 95, there is no problem such as a response delay with respect to the valve closing signal as in the prior art, and the reliability is high.
[0012]
Furthermore, the inventors have proposed a variable discharge high pressure pump in which the control of the intake amount of low pressure fuel from the low pressure flow path to the pressure chamber is performed by a variable throttle valve instead of the electromagnetic valve. . In this variable discharge high pressure pump, the suction amount is adjusted by controlling the lift amount (flow path area) of the variable throttle valve (area metering type).
[0013]
[Problems to be solved by the invention]
However, this area metering type variable discharge high pressure pump has the following problems. FIG. 16 is a time chart showing the behavior of the plunger and the cam lift when the engine is rotating at a low speed and at a high speed. Since the cam rotates in synchronism with the rotation of the engine, the cam movement is slow at low speed and the suction time of low-pressure fuel is long, and at high speed, the cam movement is fast and the suction time of low-pressure fuel is short. Therefore, in order to obtain a certain amount of inhalation, it is necessary to reduce the opening degree at low speed and increase it at high speed.
[0014]
FIG. 17 shows the characteristics of the pumping amount and the opening degree (lift amount) of the variable throttle valve. As described above, since the suction time becomes longer as the rotation speed is lower, the rate of change in the pumping amount with respect to the lift amount of the variable throttle valve (the slope of the graph (Δq / Δl)) increases. In this way, the dynamic range of the opening of the variable throttle valve changes depending on the engine speed, and as a result, when using a variable throttle valve that does not have a very high control accuracy of the opening degree, the variable discharge high pressure pump The metering accuracy of the pumping amount is not always sufficient, and the common rail pressure may fluctuate and the desired fuel injection amount may not be obtained. Therefore, in order to ensure the adjustment accuracy of the lift amount of the variable throttle valve, it is necessary to drive the valve body of the variable throttle valve with an actuator having high resolution. For example, the actuator that drives the valve body of the variable throttle valve is a step motor. If there is a linear solenoid, the displacement range of the lift amount must be increased in order to moderate the opening degree change with respect to the lift amount change, and as a result, the cost of the variable throttle valve can be further reduced. The size of the valve body in the lift direction cannot be sufficiently reduced.
[0015]
Therefore, an object of the present invention is to improve the metering accuracy by using a small, low-cost variable throttle valve whose opening degree adjustment accuracy is not so high in an area metering type variable discharge high pressure pump. . Another object of the present invention is to provide a common rail fuel injection control device that can control the common rail pressure with high accuracy by adjusting the metering accuracy of the variable discharge high pressure pump in a small size and at low cost.
[0016]
[Means for Solving the Problems]
  In the configuration of the first aspect of the present invention, the variable discharge high pressure pump has a plunger fitted in the cylinder so as to be reciprocally movable, and a pressure chamber is formed by the inner wall surface of the cylinder and the end surface of the plunger. Low-pressure fluid is sucked into the pressure chamber from the low-pressure channel, and the plunger is driven in the direction in which the pressure chamber shrinks by the plunger driving means, and the low-pressure fuel introduced into the pressure chamber is pressurized and fed to the high-pressure channel. To do. In addition, a variable throttle valve that operates freely between the low-pressure flow path and the pressure chamber, and a communication between the pressure chamber and the variable throttle valve when suctioning low-pressure fluid from the variable throttle valve to the pressure chamber. And a check valve that shuts off the pressure chamber and the variable throttle valve from the start of pressurization of the low pressure fluid sucked into the pressure chamber to the end of pressurization of the pressurized fluid to the high pressure flow path. . In addition to such a configuration, when the pressurized fuel is not pumped, an opening period and a closing period in which the variable throttle valve is opened are set, and an opening in the opening period and a time ratio between the opening period and the closing period are as follows: Control means for adjusting the amount of low-pressure fluid sucked into the pressure chamber is provided.The control means adjusts the suction amount by controlling both the suction speed determined by the opening degree of the variable throttle valve and the suction time determined by the time ratio between the open period and the closed period in the low rotation speed range of the pump.
[0017]
In the above configuration, the low pressure fluid is sucked into the pressure chamber from the variable throttle valve when the check valve is opened. By the operation of the plunger by the plunger driving means, the pressure chamber starts to shrink, and the low-pressure fluid in the pressure chamber is pressurized. As a result, the check valve is closed and the pressurized fluid in the pressure chamber is pumped to the high-pressure channel. The control means controls the suction speed of the low-pressure fluid into the pressure chamber by adjusting the opening of the variable throttle valve, and adjusts the time ratio between the open period and the closed period of the variable throttle valve to reduce the suction time. Control and adjust the amount of low-pressure fluid sucked into the pressure chamber. Even if the required amount of pressurized fuel to be pumped, that is, the amount of adjustment into the pressure chamber exceeds the adjustment accuracy of the opening of the variable throttle valve, it is possible to accurately adjust the time ratio. A desired pumping amount of pressurized fuel can be obtained. Thus, even if a small and low-cost variable throttle valve that does not have very high adjustment accuracy of the opening degree is used, the fuel pumping amount can be accurately controlled.
[0018]
In the second aspect of the present invention, the control means is set so that the open period of the variable throttle valve is synchronized with the plunger driving means.
[0019]
As a result, low-pressure fluid is sucked into the pressure chamber from the variable throttle valve at the same timing every cycle. Therefore, the variation in the intake amount between cycles is suppressed, and the metering accuracy of the intake amount is improved.
[0020]
According to a third aspect of the present invention, a plurality of cylinders and plungers constituting the pressure chamber are provided, and the plungers are driven at timings shifted from each other, and the check valve is provided corresponding to each pressure chamber. Thus, a plurality of pressure feeding systems from the low pressure channel to the pressure chamber are provided. The variable throttle valve constituting the pressure feeding system is common.
[0021]
The low pressure fluid is pumped at a timing shifted from each other by the plurality of pumping systems, and the peak driving torque in the plunger driving can be reduced. In addition, even if the suction stroke of the other pumping system is started by the end of the suction stroke of one of the pumping systems, the suction speed of the low-pressure fluid sucked into the pressure chamber of one pumping system at that time is Since it is defined by the opening of the variable throttle valve, the metering accuracy does not decrease even when the intake amount is small. Since the suction amount control of a plurality of pumping systems is performed by a single variable throttle valve, variations in the suction amount among the pumping systems can be suppressed.
[0022]
In the configuration of claim 4 of the present invention, the common rail fuel injection control device stores pressure by the variable discharge high pressure pump according to each of the above claims and the pressurized fuel pressurized by the variable discharge high pressure pump. A common rail that supplies high-pressure fuel to an electromagnetic fuel injection valve that injects fuel into each cylinder, and common rail pressure detection means that detects common rail pressure are provided. The plunger driving means of the variable discharge high-pressure pump is configured to operate in synchronization with engine rotation by engine power, and the control means sets a target pumping amount according to increase or decrease of the fuel pressure of the common rail, and sets the target pumping The variable throttle valve is controlled according to the amount.
[0023]
The target pumping amount is set according to the common rail pressure detected by the common rail pressure detecting means. The variable discharge high-pressure pump pumps pressurized fuel to the common rail with high metering accuracy according to the target pumping amount under the control of the control means. Thus, the common rail fuel pressure can be accurately controlled to the target value. In addition, as described above, the variable discharge high-pressure pump can be reduced in size and cost, whereby the common rail fuel injection control device as a whole can be reduced in size and cost.
[0024]
In the configuration of claim 5 of the present invention, the engine speed detecting means for detecting the engine speed is provided, and the control means controls the time ratio when the engine speed falls below a predetermined value, When the engine speed exceeds the predetermined value, the time ratio control is canceled.
[0025]
When the engine speed decreases and the rate of change of the pumping amount with respect to the opening of the variable throttle valve increases, the variable throttle valve is controlled by the time ratio in addition to the opening degree control. This compensates for the lack of adjustment accuracy and prevents a decrease in metering accuracy. By limiting the control of the time ratio that accompanies opening and closing of the variable throttle valve to only the low rotation range where the suction time is relatively long, the variable throttle valve does not require high responsiveness of opening and closing, further reducing costs Can be achieved.
[0026]
According to the sixth aspect of the present invention, when the common rail pressure detected by the common rail pressure detecting means changes beyond a preset predetermined value, the time ratio is controlled so that the common rail pressure is the predetermined value. If it does not exceed, the above-mentioned time ratio control is canceled.
[0027]
Since the change in the common rail pressure has increased, it can be determined that the rate of change in the pumping amount with respect to the lift amount of the variable throttle valve is increased, resulting in a decrease in metering accuracy. From this, it is known that the engine speed is in the low speed range. When such a change in the common rail pressure is detected, the metering accuracy is increased by performing the time ratio control on the variable throttle valve in addition to the opening degree control. Further, as described above, the variable throttle valve does not require high responsiveness in the low rotation range, and the cost can be further reduced.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
A variable discharge high pressure pump according to a first embodiment of the present invention and a common rail fuel injection control apparatus using the variable discharge high pressure pump will be described below with reference to the drawings. FIG. 1 shows an overall cross section of a variable discharge high pressure pump, and FIG. 2 shows the configuration of a common rail fuel injection control device. In FIG. 2, the engine E is provided with a plurality of injectors I serving as electromagnetic fuel injection valves corresponding to the combustion chambers of the respective cylinders, and these injectors I are connected to a common rail R common to the respective cylinders. Is to be supplied. The common rail R is connected to a pump portion P0 of a variable discharge high pressure pump P via a supply pipe R1 and a discharge valve B2. The variable discharge high pressure pump P continuously supplies the common rail R with a high predetermined value corresponding to the fuel injection pressure. Pressure fuel is accumulated.
[0029]
The variable discharge amount high-pressure pump P pressurizes the fuel sucked from the fuel tank T through the feed pump P1 built in the fuel tank T, supplies the fuel into the common rail R, and increases the fuel in the common rail R to high pressure. An electronic control unit (ECU) P3, which is a control means, is provided to control the common rail R at the predetermined high pressure. The ECU P3 determines the pumping amount to the common rail R so that the signal from the pressure sensor S1 that is disposed on the common rail R and serves as a common rail pressure detecting means for detecting the common rail pressure has a preset optimum value. A control signal is output to P2. The ECU P3 further includes information on the engine speed, the TDC (top dead center) sensor S3, the throttle sensor S4, and the temperature sensor S5. The ECU P3 outputs a control signal to the injection amount control electromagnetic valve B1 of the electromagnetic fuel injection valve I in accordance with the engine state determined by these signals. The configuration of the ECUP3 is arbitrary, such as a configuration including a microcomputer.
[0030]
The variable discharge high-pressure pump P will be described in more detail with reference to FIGS. FIG. 3 shows a cross section taken along the line AA in FIG. 1, and FIG. 4 is an enlarged view of the injection amount control device P2. A drive shaft D is rotatably supported in the pump housing 1 via a bearing D2 and a bush D1, and the drive shaft D sucks up fuel from the fuel tank T (FIG. 2) and serves as a low-pressure flow path. A vane type feed pump P <b> 1 that supplies pressure to the feed flow path 11 is connected. A cam 13 serving as a plunger driving means is integrally formed at the right end portion of the drive shaft D, and the cam 13 is synchronized with the engine rotation at a speed ½ of the engine speed together with the drive shaft D. It is designed to rotate. When the cam 13 rotates, the rotor P12 of the feed pump P1 rotates through the plate P11. Due to the rotation, the fuel from the fuel tank T passes through a flow path (not shown) from the inlet valve B3 to the inner space of the feed pump P1 ( The space surrounded by the rotor P12, the casing P13, and the covers P14 and P15). The introduced fuel is pumped to the feed flow path 11 through a flow path (not shown) by the vane P16 disposed in the rotor P12 as the rotor P12 rotates.
[0031]
The fuel in the feed passage 11 is not only used for pressure feeding to the common rail R as described below, but also flows into the pump portion P0 from the throttle passage S and is used for lubrication and cooling inside the pump portion P0. Is done. The fuel used for lubrication leaves the valve V and is returned to the fuel tank T. Further, the pressure inside the pump part P0 is adjusted by the valve V so as to be almost atmospheric pressure.
[0032]
A head H is fitted into the right end opening of the pump housing 1, and the head H protrudes from the center of the left end and is inserted into the cam 13. In the center of the left end of the head H, a plurality of sliding holes 2 that are cylinders are formed radially at intervals of 90 ° in a direction perpendicular to the axis of the drive shaft D. Plungers 21 are supported in the plurality of sliding holes 2 so as to reciprocate and slide freely. A shoe 211 is provided at the outer end of each plunger 21, and the cam roller 22 is rotatably held by each shoe 211. The shoe 211 is slidably held by the guide GD and can move only in the radial direction. The guide GD is fixed to the head H with bolts (not shown).
[0033]
The cam 13 is slidably disposed on the outer periphery of the cam roller 22, and a cam surface 13 a having a plurality of cam peaks arranged at equal intervals is formed on the inner peripheral surface of the cam 13. . A space formed between the inner end surface of each plunger 21 and the inner wall surface of each sliding hole 2 is a pressure chamber 23. Thus, when the cam 13 integrated with the drive shaft D rotates, the plunger 21 reciprocates in the sliding hole 2 to pressurize the fuel in the pressure chamber 23. Here, four cam ridges are formed for the four plungers 21, and the cam 13 is pumped four times for one rotation. FIG. 3 shows a state where the plunger 21 is at the highest point (innermost).
[0034]
In the conventional variable discharge high pressure pump, a spring that always presses the plunger 21 against the inner cam 13 is often provided. However, the variable discharge high pressure pump P is a suction amount control system, and the suction amount is small. If the plunger 21 is lowered to the lowest point, the cavitation may occur due to the pressure chamber 23 being depressurized. For this reason, in the present invention, the spring is not provided, and the reciprocating motion of the plunger 21 is performed by a cam lift by the rotation of the drive shaft D during the pressure feeding stroke, and by the pressure of the low pressure fuel (feed pressure) during the suction stroke. Therefore, when the intake amount is small, the plunger 21 moves only in the direction of the cam 13 by the amount of low-pressure fuel supplied, and the cam roller 22 and the inner cam 13 are separated from each other, and the intake amount depends on the intake speed. It is a quantity method.
[0035]
In the pressure chamber 23, pressurized fuel is pumped from the discharge hole 24 communicating with the pressure chamber 23 to the common rail R (FIG. 2) through the discharge valve 3 (B2 in FIG. 2) fixed to the head H wall. The The discharge valve 3 has a valve body 31 and a return spring 32 that urges the valve body 31 in the valve closing direction. When the pressurized fuel exceeds a predetermined pressure, the discharge valve 3 opens against the spring force of the return spring 32, and the high pressure flow. The pressurized fuel is discharged into the discharge flow path 33 which is a path.
[0036]
At the right end of the head H, a hole H1 communicating with the pressure chamber 23 via the communication channel 14 is formed on the right side of the pressure chamber 23. The hole H1 has a stopper 41 and a check valve from the bottom side. 4. A lock adapter LA is assembled. The stopper 41 and the check valve 4 are fixed to the head H by screwing the lock adapter LA to the head H. The lock adapter LA is fitted with the variable throttle valve 5 that constitutes the discharge amount control device P2 of FIG. 2 together with the check valve 4, and the tip is opposed to the check valve 4. A fuel reservoir 12 is formed on the outer periphery of the tip of the check valve 4 and the lock adapter LA, and a fuel reservoir 52 is formed on the outer periphery of a valve body 71 (to be described later) of the variable throttle valve 5. The fuel reservoir 12 and the fuel reservoir 52 communicate with each other through a flow path 51 formed in the lock adapter LA. A low pressure channel is formed by the feed channel 11, the feed channel 11 a of the head H, the fuel reservoir 12, the channel 51, and the fuel reservoir 52.
[0037]
As shown in FIG. 4A, the check valve 4 includes a flow path 43 that penetrates the housing 42 in the left-right direction and a valve body 44 that opens and closes the flow path 43. The channel 43 is enlarged in the direction of the pressure chamber 23 (leftward in the drawing) to form a conical sheet surface 45. As shown in FIG. 4B, the valve body 44 has grooves 44a at four locations on the outer peripheral surface, and a flow path 43 is formed along the cutting surface so that fuel flows. .
[0038]
The valve body 44 is urged rightward by a spring 46 held in the stopper 41 and is seated on the seat surface 45. Thus, the check valve 4 is closed in the state shown in the figure, and is opened by the pressure of the fuel flowing from the variable throttle valve 5.
[0039]
A plurality of communication holes 41a and 41b are formed in the stopper 41, and fuel can flow between the flow path 43 and the pressure chamber 23 through the communication holes 41a and 41b. The valve body 44 is easily subjected to the dynamic pressure of the fuel flowing backward from the pressure chamber 23 by the communication hole 41b in the central portion of the stopper 41, and the valve closing response is enhanced.
[0040]
Accordingly, when the check valve 4 is opened by the pressure of the fuel flowing in from the variable throttle valve 5, the pressure chamber 23 (see FIG. 5) passes through the seat surface 45 of the check valve 4 and the flow paths 41a and 41b in the stopper 41. Fuel flows into 1). When the pressurization of the pressure chamber 23 is started, the valve body 44 is closed by the dynamic pressure, and is held until the fuel pressure is finished.
[0041]
The variable throttle valve 5 includes an actuator 6 and a valve portion 7, and a valve body 71 of the valve portion 7 is fitted and fixed via a housing 61 of the actuator 6 and an annular shim 77 in the left end portion thereof. A valve body 73 is slidably held in a cylinder 72 provided in the valve body 71, and the actuator 6 drives it.
[0042]
An annular channel 74a is formed around the left end portion of the valve body 73. The channel 74a communicates with the fuel reservoir 52 through the channel 74b and communicates with the check valve 4 through the channel 74c.
[0043]
The valve body 73 is formed with a bowl-shaped enlarged diameter portion 73a, and the position where the right end of the enlarged diameter portion 73a contacts the shim 77 defines the right limit of the movement range. In the left limit, the left end tapered surface 76 of the valve body 73 is defined by the seat surface 75 of the valve body 71.
[0044]
An armature 64 is press-fitted and fixed to the right end of the valve body 73, and the armature 64 faces the stator 65 at a constant interval. The coil 62 is disposed on the outer periphery of the stator 65. A spring 67 is disposed in a spring chamber 66 provided inside the stator 65, and urges the armature 64 to the left in the drawing. On the other hand, the stator 65 generates a force for attracting the armature 64 (force for urging rightward in the drawing) by energizing the coil 62 from the ECU P3.
[0045]
A substantially conical seat surface 75 is formed at the open end of the flow path 74c, and the leading end of the valve element 73 is seated on the seat surface 75 in a state where the coil 62 is not energized. 74a and 74c are cut off.
[0046]
The cross-sectional area of the facing portion 65a of the stator 65 facing the armature 64 is made smaller toward the armature 64 side. Therefore, the lift amount of the valve body 73 integrated with the armature 64 is determined by the energization current to the coil 62. That is, the variable throttle valve 5 is a linear solenoid valve. Therefore, when the coil 62 is energized, the valve element 73 is lifted and the flow path 74a and the flow path 74c are communicated, and when the energization current is increased, the opening area of the communication portion is increased according to the energization current. That is, the opening degree of the variable throttle valve 5 increases.
[0047]
FIG. 5 is an enlarged view of the valve portion of the variable throttle valve 5. The valve body 73 has a valve diameter d1 of 3.0 mm and an inclination angle θ1 of the tip surface of the valve body 73 of 30 °, and the conical surface 75 of the seat surface on the flow path 74c side has a right end diameter of 3.1 mm and an inclination angle θ2. Is 28 °.
[0048]
Since the structure of the right end portion of the valve body 73 is as described above, when the valve is closed, the seal edge 76a of the conical surface 76 of the valve body 73 is in close contact with the seal surface 75 and the flow path 74a and the flow path 74c are blocked. Is done. Therefore, when the valve is closed, the force in the valve opening direction is not received by the pressure of the flow path 74a, that is, the fuel reservoir 52.
[0049]
Note that when the variable throttle valve 5 is opened, the armature 64 moves to the right, and the volume of the spring chamber 66 decreases accordingly, so that the spring chamber 66 can be moved away from other parts so that the fuel in the spring chamber 66 can move. It is necessary to communicate. In the present embodiment, a flow path 78 that penetrates the valve body 73 in the left-right direction is provided inside the valve body 73 and communicates with the spring chamber 66 and the flow path 74 c on the left side of the needle valve 73. As a result, the fuel in the spring chamber 66 can move, and at the same time, even if the pressure in the flow path 74c rises when the valve is opened, the spring chamber 66 and the flow path 74c have the same pressure. Oil pressure does not act, and malfunction of the valve body 73 can be prevented.
[0050]
Since no oil pressure acts on the valve body 73 in this way, the spring force of the spring 67 may be small, and a linear solenoid valve with a small suction force can be operated. In this embodiment, the diameter of the seal edge is made equal to the diameter of the valve body, but it may be made slightly smaller as long as the valve body 73 does not malfunction.
[0051]
Next, the operation of the variable discharge high pressure pump P and the common rail fuel injection control device will be described. As described above, the variable discharge high pressure pump P is configured such that the suction and pumping strokes are performed for four cycles per rotation of the cam 13, and the pumping amount is controlled by the amount of fuel sucked into the pressure chamber 23. Here, the inhalation amount Q is expressed by the following equation.
Inhalation Q = α × S × √ (ΔP) × Time
α: Flow coefficient
S: Opening area of variable throttle valve 5
ΔP: Feed pressure
Time: Determined by pump speed
That is, when α, ΔP and time are constant, it is understood that the intake amount Q can be controlled by adjusting the opening of the variable throttle valve 5. That is, the larger the opening of the variable throttle valve 5, and thus the larger the opening area, the larger the suction amount, and the smaller the opening area, the smaller the suction amount. As described above, the lift (opening degree) of the valve element 73 of the variable throttle valve 5 is determined at a position where the attractive force against the armature 64 and the spring force of the spring 67 are in accordance with the energization current value of the coil 62.
[0052]
That is, the lift amount of the valve body 73 can be adjusted by changing the current value to the coil 62. If the current value is increased, the suction force against the armature 64 increases and the lift amount (opening degree) of the valve body 73 increases. ) Increases, and the inhalation amount Q increases.
[0053]
The discharge amount control, that is, the suction amount control to the pressure chamber, performed in the ECU P3 of the variable discharge amount high-pressure pump P will be described. FIGS. 6 and 7 are time charts showing such suction amount control. NE pulse, operation of the variable throttle valve 5 (the energization current to the coil 62, the lift amount of the valve element 73, the lift of the cam 13, and the locus of the cam roller 22). FIG. 6 shows a comparison of pressure feeding patterns (for example, opening / closing valve patterns of the discharge valve 3.) The first half of the time chart is when the suction amount is small, and the second half is when the suction amount is large. 2 is a signal after the waveform of the output signal from the engine speed sensor S2 is processed by the ECU P3, and the phase of cam movement of the cam 13 is known from this signal, and this NE pulse and load sensor S3, pressure sensor S1, and further Based on signals from a water temperature sensor and an atmospheric pressure sensor (not shown), the ECU P3 controls the energization of the coil 62 of the variable throttle valve 5 to suck the low-pressure fuel into the pressure chamber 23. Control to.
[0054]
The operation in the high rotation range will be described with reference to FIG. The energizing current is adjusted to control the suction amount Q. That is, when the intake amount is small, the energization current to the coil 62 of the variable throttle valve 5 is reduced, the lift amount of the valve element 73 is reduced, and the opening area is reduced. As a result, during the intake stroke of the cam 13 (from time a to time b), the low pressure fuel is slowly sucked into the pressure chamber 23 at a slow suction speed. At this time, the cam roller 22 and the cam 13 of the plunger 21 are not in sliding contact, and the plunger 21 gradually descends (moves in the radial direction, see FIG. 3) as the fuel is sucked. When the cam 13 comes into contact with the cam roller 21a and the plunger 21 starts to rise (moving toward the center of the radius) (time point b in the figure), the pressure feed stroke (from time point b to time point c) starts. That is, the plunger 21 is lifted by the pushing force of the cam 13 against the cam roller 22, and the fuel in the pressure chamber 23 is pressurized and fed to the common rail R.
[0055]
In this pressure-feeding stroke, the pressure of pressurized fuel is applied to the check valve 4, so that the valve body 44 does not open. Therefore, the amount of suction into the pressure chamber 23 is the pressure feed amount.
[0056]
When the intake amount is increased, the energizing current to the coil 62 of the variable throttle valve 5 is increased, the lift amount of the valve element 73 is increased, and the opening area is increased. As a result, the inflow speed of the fuel flowing into the pressure chamber 23 from the variable throttle valve 5 through the check valve 4 is increased, the plunger 21 is lowered at a high speed, and comes into contact with the rising cam 13 at an early timing. 23, a larger amount of low-pressure fuel is sucked than when the suction amount is made small.
[0057]
Thus, the larger the lift amount of the valve element 73 of the variable throttle valve 5, the greater the stroke of the plunger 21 and the greater the intake amount. Here, the pumping amount per cycle is expressed by plunger lift × plunger diameter × plunger number (4 in the example).
[0058]
On the other hand, in the low speed range, in addition to the energization current, the energization time is adjusted to control the intake amount Q. That is, as described above, the dynamic range of the opening degree of the variable throttle valve 5 is different from that in the high rotation range, and in order to suck the same amount of low-pressure fuel, the lift amount of the valve body 73 compared to the high rotation range, and accordingly It is necessary to reduce the energization current to the coil 62. However, even if the energization current is increased or decreased by the minimum step, the inhalation amount greatly increases or decreases as the inhalation time is longer. Therefore, in the present invention, an open period in which the valve element 73 is open and a closed period in which the valve body 73 is closed are set for each suction pressure feeding process at the time of non-pressure feeding. That is, the coil 62 is not always energized, but is energized corresponding to the open period, and energization is stopped corresponding to the closed period.
[0059]
Time control for controlling the ratio of the energization time will be described. In FIG. 7 showing the operation in the low rotation range, when the intake amount is made small, the energization current to the coil 62 of the variable throttle valve 5 is made smaller than that in the high rotation range as described above, and the energization is stopped. Provide a closing period. Thus, in the open period, the low pressure fuel is sucked into the pressure chamber 23 and the plunger 21 descends. However, when the closing time starts, the suction of the low pressure fuel into the pressure chamber 23 stops and the plunger 21 descends further as shown in the figure. Without displacement, the displacement is maintained. Thereafter, the cam 13 is brought into contact with the cam 13 turned upward, and is pumped to the common rail R through the discharge valve 3. In this way, the amount of pumping, that is, the amount of suction into the pressure chamber 23 is given in proportion to the opening of the valve element 73 in the open period, that is, the energizing current value to the coil 62, and the ratio of the open period and the closed period. The same applies when the inhalation amount is increased. The energization of the coil 62 is started slightly before the cam maximum rise time in consideration of the valve opening response of the valve element 73 of the variable throttle valve 5 so that the opening period is immediately after the end of the pumping stroke. .
[0060]
In the low rotation range, the suction time is set relatively long and the opening degree is set small. Therefore, even if the lift and fall of the valve body 73 are not steep at the start point and end point of the closing period, the effect on the metering accuracy is small, and the variable throttle valve 5 does not necessarily have a good response. For example, a linear solenoid valve can be used.
[0061]
Further, since the energization to the solenoid 62 in each cycle is given so as to synchronize with the cam movement based on the NE pulse, the low pressure fuel is sucked into the pressure chamber 23 from the variable throttle valve 5 at the same timing every cycle. . Therefore, the variation in the intake amount between cycles is suppressed, and the metering accuracy of the intake amount is improved.
[0062]
By performing the time control for controlling the ratio of the energization time to the coil 62 in this way, it is possible to control the intake amount of the low-pressure fuel into the pressure chamber 23 with high accuracy comparable to the high rotation range.
[0063]
FIG. 8 is a flowchart showing an example of common rail pressure control by the ECU P3. As shown in the configuration diagram of FIG. 2, the ECUP3 is constantly inputted with various information from each sensor, and the engine (pump) rotation is detected from the NE signal detected by the engine speed sensor S2. The target common rail pressure (CPTRG) and the injection amount (pumping amount) are calculated from the accelerator opening detected by the throttle sensor S4 based on the previously input control map (step (1), step (2)). ). Subsequently, an energization current value of the variable throttle valve 5 corresponding to the pump rotation speed and the pumping amount is calculated (step (3)), and the variable throttle valve 5 is energized.
[0064]
The ECU P3 always detects the common rail R pressure (CPACT) by the pressure sensor S1, and compares the detected common rail R pressure (CPACT) with the target common rail pressure (CPTRG) (step ( 4)) If they are different, correct them. As a correction method, calculation of (CPACT-CPTRG) is performed to calculate a necessary increase in pumping amount (step (5)).
[0065]
In step (6), it is determined whether or not the engine speed has exceeded 1500 rpm. If the engine speed exceeds 1500 rpm, it is determined that the engine speed is high, and the control of FIG. 6 is performed in which the coil 62 of the variable throttle valve 5 is always energized. That is, in step (7), the energization current to the coil 62 is changed to a current value corresponding to the increase / decrease in the pumping amount calculated in step (5), and the process proceeds to step (9).
[0066]
If the engine speed does not exceed 1500 rpm in step (6), it is determined that the engine is in the low speed range, and the time control in FIG. 7 is performed. That is, in step (8), the energization current to the coil 62 is changed to the energization time (duty) corresponding to the increase / decrease in the pumping amount calculated in step (5), and the process proceeds to step (9). In step (8), if it is necessary to increase the pumping amount, the energization current is increased by one minimum step, and the energization time (duty) is decreased therefrom.
[0067]
In step (9), it is determined again whether or not (CPACT = CPTRG). If not (CPACT = CPTRG), the process returns to step (5) and repeats feedback control until (CPACT = CPTRG).
[0068]
FIG. 9 shows the pumping characteristics in this embodiment. In the high speed range, since the change in the pumping amount is small with respect to the minimum opening step, the change control is discretely performed to a current value different from the minimum opening step with respect to the requested value of the pumping amount. For example, as shown in the figure, the current is controlled between i1 and i2, the lift amount is changed between l1 and l2, and (1) and (2) are repeated, so that the pumping amount Q is accurately requested. Can be maintained. On the other hand, in the low rotation range, the difference Δq in the pumping amount is large between the currents i3 and i4 separated by the minimum step (lift amounts l3 and l4). The pressure fluctuates greatly. However, in the low rotation range, the time control is performed as described above, and the duty is adjusted to change from (1) 'to (2)' while maintaining the current at i3. Therefore, high metering accuracy can be obtained even in a low rotation range.
[0069]
In this way, in the low rotation range where the metering accuracy is reduced only by the opening control by the control of the energized current value, the metering accuracy is increased by performing time control, so that the variable throttle valve has a high opening resolution. Can be used, and a small and inexpensive one can be used.
[0070]
In this embodiment, the engine speed threshold value for determining whether or not to perform time control is set to 1500 rpm. However, the present invention is not necessarily limited to this, and an actuator for driving the valve body of the variable throttle valve. In addition to the accuracy and resolution, it is set as appropriate according to the responsiveness. For example, if a variable throttle valve with good responsiveness can be used, the adjustment error due to the rise and fall of the lift will not be a problem even in the high rotation range. It may be configured to control the amount. Even in such a configuration, since the ECU performs time control to improve the metering accuracy, a variable throttle valve having a high opening resolution is unnecessary, and a small and inexpensive one can be used.
[0071]
The determination as to whether or not to perform time control is not necessarily limited to the comparison with the predetermined value of the engine speed. For example, when the energizing current is changed (when the lift amount of the valve body 73 is changed), the fluctuation of the fuel pressure of the common rail R is calculated, and when this exceeds a predetermined value, the pumping amount with respect to the lift amount is calculated. A configuration may be adopted in which it is determined that the rate of change is large and switching to time control is performed.
[0072]
(Second Embodiment)
In the common rail fuel injection control apparatus, the variable discharge high-pressure pump may have a different configuration. Since the entire configuration of the common rail fuel injection control device is the same as that of FIG. 2, only the variable discharge high pressure pump is shown in FIGS. FIG. 10 shows an overall cross section of the variable discharge high pressure pump, and FIG. 11 shows a cross section taken along the line CC in FIG. The pump section P0A of the variable discharge amount high-pressure pump PA has substantially the same basic configuration as that of the first embodiment, but includes two pumping systems. That is, at the center of the left end of the head H, sliding holes 2a, 2b, 2c, 2d, which are four cylinders, are formed radially at intervals of 90 ° in a direction perpendicular to the axial direction of the drive shaft D. It is. The sliding hole 2a and the sliding hole 2c formed along the same axis line, and the sliding hole 2b and the sliding hole 2d communicate with each other through communication passages 25a and 25b having a smaller diameter than the sliding hole diameter. Plungers 21a to 21d are arranged in the respective sliding holes 2a to 2d, and are supported so as to be reciprocally movable and slidable with respect to the respective sliding holes 2a to 2d. Four spaces formed by the inner wall surfaces of the sliding holes 2a to 2d and the end surfaces of the plungers 21a to 21d are respectively pressure chambers 23a, 23b, 23c, and 23d.
[0073]
A shoe 211 and a cam roller 22 are provided corresponding to the plungers 21a to 21d. Further, an inner cam 13A as a plunger driving means is provided so as to be slidable in contact with each cam roller 22, and the plungers 21a to 21d are reciprocally moved in common. The inner cam 13A has two cam ridges in one rotation, and is cammed at an upward 120 ° and a downward 60 °. The adjacent plungers 21a and 21c and plungers 21b and 21d form 90 ° with each other. Reciprocates at different timing. In the following description, the fuel pumping part composed of the sliding hole 2a and the plunger 21a is the # 1 cylinder, the fuel pumping part composed of the sliding hole 2b and the plunger 21b is the # 2 cylinder, and the sliding hole 2c. And the fuel pumping part composed of the plunger 21c is referred to as # 3 cylinder, and the fuel pumping part composed of the sliding hole 2d and the plunger 21d is referred to as # 4 cylinder.
[0074]
The pressure chambers 23a and 23d communicate with the inlets of the valve portions 3a and 3b of the discharge valve 3A through the individual flow paths 14a and 14d, respectively. The discharge valve 3A is substantially a combination of the two discharge valves of the first embodiment, and is a check valve whose forward direction is the direction flowing in from the pressure chambers 23a to 23d. The valve portions 3a and 3b are It communicates with a common discharge channel 33.
[0075]
The head H is formed with a pair of holes H2a and H2b from the right side, and one ends of the flow paths 16a and 16b are opened on the bottom surfaces of the holes H2a and H2b, respectively. The flow paths 16a and 16b communicate with a communication path 25a that communicates the pressure chamber 23a and the pressure chamber 23c, and a communication path 25b that communicates the pressure chamber 23b and the pressure chamber 23d, respectively. The holes H2a and H2b communicate with the outlet-side flow path 15 of the variable throttle valve 5.
[0076]
A gasket 47, a stopper 41, and check valves 4a and 4b are fitted in the holes H2a and H2b, respectively. The check valves 4a and 4b have the same structure, and have a housing 42 and a bolt 48, and the housing 42, the stopper 41 and the gasket 47 are fixed to the head H by screwing the bolt 48 into the holes H2a and H2b. ing. Each housing 42 of the check valves 4a and 4b is formed with a flow path 431 penetrating in the axial direction thereof and a flow path 432 crossing the flow path 431. The flow path 431 is formed by the flow paths 41a and 41b of the stopper 41. And the flow paths 16a and 16b communicating with the pressure chambers 23a and 23c, 23b and 23d, and the flow path 432 communicates with the outlet of the variable throttle valve 5 via the outlet side flow path 15.
[0077]
The flow path 431 has a valve body 44 that opens and closes the flow path 431 at the large diameter portion on the stopper 41 side, and the valve body 44 is seated on a seat surface 45 formed in the flow path 431 so as to face the valve body 44. It is urged in the seating direction by a spring 46 held inside. As shown in FIG. 11B, the valve body 44 has grooves 44a at four locations on the outer peripheral surface, and a flow path 431 is formed along the cutting surface so that fuel flows. .
[0078]
Thus, the check valves 4a and 4b are closed in the state shown in the drawing, and are opened by the pressure of the fuel flowing in from the variable throttle valve 5, so that the pressure chamber 23 is pressurized. When started, the valve is closed and held until the fuel pumping is completed.
[0079]
Thus, the low-pressure fuel from the feed passage 11 is sucked into the pressure chambers 23a and 23c from the check valve 4a through the variable throttle valve 5, and from the pressure chambers 23a and 23c to the common rail R through the valve portion 3a of the discharge valve 3A. The low pressure fuel from the first pressure feeding system (see FIG. 2) and the feed flow path 11 is sucked into the pressure chambers 23b and 23d from the check valve 4b through the variable throttle valve 5, and the pressure chamber 23b. , 23d through the valve part 3b of the discharge valve 3A to the common rail R (see FIG. 2), the second pressure feeding system is formed with the variable throttle valve 5 in common.
[0080]
The operation of the common rail fuel injection control apparatus according to this embodiment will be described. The ECU P3 controls the common rail pressure according to the control of the first embodiment (the flowchart of FIG. 8). 12 and 13 are time charts for explaining the suction amount control to the pressure chambers 23a to 23d. FIG. 12 shows the high rotation speed and FIG. 13 shows the low rotation speed.
[0081]
Similar to the first embodiment, when the engine speed exceeds 1500 rpm, it is determined that the engine speed is high, and the intake amount is controlled by controlling only the opening of the variable throttle valve 5. That is, in order to increase the discharge amount, the energization amount is increased to increase the opening of the variable throttle valve 5, and when the intake amount is decreased, the energization amount is decreased. In the figure, the case where the amount of inhalation is small, the case of medium, and the case of large are also shown.
[0082]
Since the # 1, # 3 cylinder and the # 2, # 4 cylinder have different 90 ° forming directions, the cam lift is 90 ° out of phase with the pump rotation (rotation of the drive shaft D). Thus, in the # 1 and # 3 cylinders, the suction stroke is from the time point a to the time point d, and the pumping stroke is from the time point d to the time point e, and in the # 2 and # 4 cylinders, the suction stroke is from the time point c to the time point e. Until the time point, the pumping stroke is from time point b to time point c.
[0083]
Now, from the time point a to the time point b, the low pressure fuel from the variable throttle valve 5 is diverted to the pressure chambers 23a to 23d for the intake strokes in the # 1, # 3 cylinder, # 2, and # 4 cylinders, and the plungers 21a to 21d. The lift is moderate. At time point b, the # 1 and # 3 cylinders continue to inhale, but the # 2 and # 4 cylinders enter the pressure stroke. Therefore, the low pressure fuel from the variable throttle valve 5 flows only into the pressure chambers 23a and 23c corresponding to the # 1 and # 3 cylinders, and the lifts of the # 1 and # 3 cylinders become steep.
[0084]
At time point c, the # 2 and # 4 cylinders have completed the pressure feed stroke and the suction stroke is started again, so that the lifts of the plungers 21a to 21d are gentle in both the # 1, # 3 cylinder, and the # 2 and # 4 cylinders.
[0085]
At time d, the # 2 and # 4 cylinders continue to inhale, but the # 1 and # 3 cylinders enter the pressure stroke. Therefore, the low pressure fuel from the variable throttle valve 5 flows only into the pressure chambers 21b and 21d corresponding to the # 2 and # 4 cylinders, and the lifts of the # 2 and # 4 cylinders become steep.
[0086]
Next, the control in the low rotation range will be described with reference to FIG. When the engine speed falls below 1500 rpm, it is determined that the engine speed is low, and the intake amount is controlled by time control in addition to opening control of the variable throttle valve 5. That is, in order to increase the intake amount, the energization amount is increased to increase the opening of the variable throttle valve 5, and when the intake amount is decreased, the energization amount is decreased and the control shown in the time chart of FIG. The duty is determined according to steps (5) to (9)). The energization period is set in synchronism with the NE pulse, and therefore in synchronism with the engine speed, and the highest point of the cam peak corresponding to the # 1, # 3 cylinder and the cam corresponding to the # 2, # 4 cylinder. It is energized at the highest point of the mountain, that is, at the end of the pumping, and is set so that fuel is started to be sucked into the pressure chambers 23a to 23d at the suction speed corresponding to the energization amount.
[0087]
A case where the inhalation amount is small will be described. At time a ′, energization of the variable throttle valve 5 is started and the variable throttle valve 5 is opened. In the # 1, # 3 cylinder and the # 2, # 4 cylinder, the plungers 21a to 21d are lowered and suction is started. Here, for the # 1, # 3 cylinder, # 2, and # 4 cylinder, the low pressure fuel from the variable throttle valve 5 is diverted to the pressure chambers 23a to 23d due to the intake stroke, and the lifts of the plungers 21a to 21d are gentle. Since the energization is terminated and the variable throttle valve 5 is closed at the time b ′, the suction of all the cylinders is stopped, and the plungers 21 a to 21 d maintain the state at the time b ′ regardless of the lift of the cam 13. The holding state continues until the next energization start (time point d ′) in the # 1 and # 3 cylinders, and continues until the plungers 21b and 21d come into contact with the rising cam surface at the time point c ′ in the # 2 and # 4 cylinders. After that, it becomes a pumping stroke.
[0088]
At the time d ', since energization of the variable throttle valve 5 is started and the variable throttle valve 5 is opened, the # 1 and # 3 cylinders are sucked again. In addition, since the # 2 and # 4 cylinders are at the highest lift point of the cam lift, the suction is started thereafter. Here, the lifts of the plungers 21a to 21d are gradual in the same manner as described above for the # 1, # 3 cylinder, # 2, and # 4 cylinders because of the intake stroke.
[0089]
At the time e ′, the energization is ended and the variable throttle valve 5 is closed, so that the suction of all the cylinders is stopped, and the plungers 21 a to 21 d maintain the state at the time e ′ regardless of the lift of the cam 13. The holding state continues until the next energization start (time point g ′) in the # 2 and # 4 cylinders, and continues until the plungers 21a and 21c come into contact with the rising cam surface at the time point f ′ in the # 1 and # 3 cylinders. Thereafter, the pumping stroke is performed until the time point g ′ at which the cam 13 is at its highest point.
[0090]
Thus, even when the variable discharge high-pressure pump P has a plurality of pumping systems, time control is performed to compensate for the lack of adjustment accuracy of the opening of the variable throttle valve 5 and to provide metering accuracy in the low rotation range. Improve.
[0091]
Further, since the driving of the plungers 21a to 21d by the cam 13A is performed at different timings, the pumping period is different between the # 1, # 3 cylinder and the # 2, # 4 cylinder, as is known from the pumping pattern in the figure. Drive torque can be reduced. In the configuration in which the suction amount into the pressure chamber is controlled only by the energization period of the solenoid valve, which is a metering valve (FIG. 15), a plurality of pumping systems are provided, and a solenoid valve is provided for each pumping system. In order to increase the metering accuracy when the amount is small, it is necessary to provide a flat portion at the top of the cam lift to offset the variation in the valve opening response between the solenoid valves. Since the variable throttle valve is common to the pumping system, such a flat portion is unnecessary. Therefore, as long as the flat portion is not provided, it is possible to increase the climb of the cam mountain. That is, the gradient of the cam lift in the pumping stroke can be made gentle, and the peak driving torque can be further reduced to improve fuel efficiency.
[0092]
In addition, even if the suction stroke of the other pumping system is started by the end of the suction stroke of one pumping system until the pumping is started, the suction speed of the low-pressure fuel sucked into the pressure chamber of one pumping system at that time is Since it is defined by the opening of the variable throttle valve, the metering accuracy will not be insufficient even when the intake amount is small. Therefore, it is not necessary to provide a distribution rotor that distributes the low-pressure fuel from the metering valve to the pressure chamber, and the manufacturing cost can be reduced.
[0093]
In addition, although the variable discharge amount high pressure pump of each said embodiment showed what was applied to the common rail type fuel-injection control apparatus, it is not necessarily limited to this.
[Brief description of the drawings]
FIG. 1 is an overall cross-sectional view of a variable discharge high-pressure pump showing a first embodiment of the present invention.
FIG. 2 is an overall configuration diagram of a common rail fuel injection control device using the variable discharge high-pressure pump according to the first embodiment of the present invention.
FIG. 3 is a cross-sectional view taken along line AA in FIG.
4A is a partially enlarged cross-sectional view of FIG. 1, and FIG. 4B is a cross-sectional view taken along line BB in FIG.
FIG. 5 is a partially enlarged cross-sectional view of a variable throttle valve of the variable discharge high-pressure pump showing the first embodiment of the present invention.
FIG. 6 is a first time chart for explaining the operation of the ECU of the variable discharge high-pressure pump according to the first embodiment of the present invention.
FIG. 7 is a second time chart for explaining the operation of the ECU of the variable discharge high pressure pump according to the first embodiment of the present invention.
FIG. 8 is a flowchart for explaining the operation of the ECU of the variable discharge high-pressure pump according to the first embodiment of the present invention.
FIG. 9 is a graph for explaining the operation of the variable discharge high-pressure pump according to the first embodiment of the present invention.
FIG. 10 is an overall sectional view of a variable discharge high-pressure pump showing a second embodiment of the present invention.
11A is a partially enlarged cross-sectional view of FIG. 10, and FIG. 11B is a cross-sectional view taken along line DD in FIG.
FIG. 12 is a first time chart for explaining the operation of the ECU of the variable discharge high pressure pump according to the second embodiment of the present invention.
FIG. 13 is a second time chart for explaining the operation of the ECU of the variable discharge high pressure pump according to the second embodiment of the present invention.
FIG. 14 is a partial sectional view of a conventional first variable discharge high pressure pump.
FIG. 15 is a sectional view of a second conventional variable discharge high pressure pump.
FIG. 16 is a time chart for explaining the operation of a conventional third variable discharge high-pressure pump.
FIG. 17 is a graph for explaining a problem of a third conventional variable discharge high-pressure pump.
[Explanation of symbols]
P Variable discharge high pressure pump
P0, P0A Pump part
P1 feed pump
P2 discharge control device
P3 ECU (control means)
I Injector (Electromagnetic fuel injection valve)
11, 11a Feed flow path (low pressure flow path)
12,52 Fuel reservoir (low pressure flow path)
13, 13A cam (plunger driving means)
2, 2a, 2b, 2c, 2d Sliding hole (cylinder)
21, 21a, 21b, 21c, 21d Plunger
22 Cam Roller
23, 23a, 23b, 23c, 23d Pressure chamber
24 Discharge hole
3,3A Discharge valve
33 Discharge flow path (high pressure flow path)
4, 4a, 4b Check valve
5 Variable throttle valve

Claims (6)

A plunger is inserted and disposed in the cylinder so as to be able to reciprocate, a pressure chamber is formed by the inner wall surface of the cylinder and the end surface of the plunger, and a low-pressure fluid is introduced into the pressure chamber from a low-pressure flow path. The plunger is driven by the driving means in a direction in which the pressure chamber shrinks, the low pressure fuel introduced into the pressure chamber is pressurized and fed to the high pressure flow path, and the low pressure flow path, the pressure chamber, Between the pressure chamber and the variable throttle valve, and when the low-pressure fluid is sucked from the variable throttle valve into the pressure chamber, the pressure chamber and the variable throttle valve communicate with each other. In a variable discharge high-pressure pump having a check valve that shuts off between a pressure chamber and a variable throttle valve from the start of pressurization to the end of pressurization of the pressurized fluid to the high-pressure flow path, When the variable throttle valve is open, Set the inter Jill closing time, with the opening in the open period, the time ratio of between open period and closing time period, comprising a control means for adjusting an intake amount of the low pressure fluid to said pressure chamber, said control means Is characterized in that the amount of suction is adjusted by controlling both the suction speed determined by the opening of the variable throttle valve and the suction time determined by the time ratio between the open period and the closing period in the low rotation speed range of the pump. Variable discharge high pressure pump.   2. The variable discharge high pressure pump according to claim 1, wherein the control means is set so that an open period of the variable throttle valve is synchronized with the plunger driving means.   3. The variable discharge high pressure pump according to claim 1 or 2, wherein a plurality of the cylinders and plungers constituting the pressure chamber are provided and the plungers are driven at timings shifted from each other, and each pressure chamber is supported. A variable discharge high pressure pump provided with a plurality of systems using the variable throttle valve in common with the check valve and a pressure feed system from the low pressure flow path to the pressure chamber.   A high pressure is applied to the variable discharge high pressure pump according to any one of claims 1 to 3 and an electromagnetic fuel injection valve that is pressurized by the pressurized fuel pressurized by the variable discharge high pressure pump and injects fuel into each cylinder of the engine. A common rail for supplying fuel, and a common rail pressure detecting means for detecting the fuel pressure of the common rail, wherein the plunger driving means of the variable discharge high pressure pump is operated in synchronization with engine rotation by engine power, 2. A common rail fuel injection control apparatus according to claim 1, wherein the control means is configured to set a target pumping amount in accordance with an increase or decrease in fuel pressure of the common rail, and to control the variable throttle valve in accordance with the target pumping amount.   5. The common rail fuel injection control device according to claim 4, further comprising an engine speed detecting means for detecting the engine speed, and the control means is configured so that the time ratio is less than a predetermined value set in advance. The common rail type fuel injection control device is configured to cancel the time ratio control when the engine speed exceeds a predetermined value.   5. The common rail type fuel injection control device according to claim 4, wherein the control means performs the time ratio control when the fuel pressure detected by the common rail pressure detecting means changes beyond a predetermined value, and the fuel ratio is controlled. A common rail fuel injection control device configured to cancel the control of the time ratio if the pressure does not exceed the predetermined value.

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