RU2285847C1 - System for adjusting continuity of switching caterpillar and wheeled vehicle transmissions - Google Patents

Abstract

FIELD: caterpillar and wheeled vehicles furnished with automatic movement controlling and adjusting system.

SUBSTANCE: system for adjusting continuity of switching transmissions of caterpillar and wheeled vehicles equipped with automatic movement controlling system has internal combustion engine, oil tank, oil pump, electric magnets, slide valves, first friction device, transmission, second friction device, commutation unit, microprocessor control unit, and controlled throttle. Throttle is located in pressure pipeline between oil tank and friction devices and is electrically connected with output of commutation unit whose input is connected to output of microprocessor control unit. Outputs of commutation unit are connected through electric magnets to inputs of slide valves, whose outputs are connected to inputs of friction devices. Adjustment system is further equipped with vehicle movement sensor connected to wheel drive, engine crankshaft rotational speed sensor, device designed for sensing oil pressure in transmission hydraulic control system and connected to inputs of friction devices, device designed for sensing oil temperature in hydraulic system and located in pressure pipeline. Outputs of said sensors are connected to respective inputs of microprocessor control unit.

EFFECT: provision for impact-free switching of transmissions and reduced dynamic loading of transmissions during switching thereof.

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Description

The invention relates to the field of tracked and wheeled vehicles equipped with an automatic motion control and control system.

It is known that (see Design and calculation of tanks. Textbook / Burov S.S. M .; Military Academy of Armored Forces named after Marshal of the Soviet Union Malinovsky R.Ya., 1973) the reliability of the stepped transmissions of wheeled and tracked vehicles is largely determined gear shift characteristics. High dynamic loads acting on the transmission components when shifting gears lead to premature wear, destruction and failure of the transmission. Therefore, when creating stepped transmissions, it is necessary to solve the problem of researching the action of friction control elements of gears in order to ensure smooth gear shifting. This task is especially relevant when automating the gear shift process.

In the case of an automatic gear shift, the driver, not knowing at what point the shift will occur, keeps the position of the fuel control unit constant during the gear shift. Due to changes in the gear ratio in the gearbox, the traction force F _T on the drive wheels before shifting the gear is not equal to the traction after shifting. The transience of the gear shifting process causes a sudden change in the force F _T. This leads to the occurrence of dynamic loads in the transmission, which in automatic mode can exceed 2-3 times the load during manual shifting (since during manual shifting, the driver at the moment of shifting, as a rule, changes the position of the fuel supply pedal).

Consider the operation of the friction elements of the gearbox during automatic shifting. To do this, consider figure 1, which presents a diagram of a dynamic model of the machine.

Gear shifting in the gearbox leads to a change in the angular velocities of the leading ω ₁ and driven ₂ parts of the clutch. This entails a change in the kinetic energies of the fly masses J ₁ and J ₂ . A flywheel with moment of inertia J ₁ characterizes the inertial properties of the rotating parts of the engine and gearbox associated with the leading part of the clutch. The value of J _{2 is} determined by the moments of inertia of the parts of the driven elements of the friction clutch, as well as the rest of the transmission, the rotating elements of the chassis and the translationally moving mass of the machine associated with them.

When switching to overdrive, the kinetic energy of mass J _{1 is} partially spent on the work of slipping the clutch control gearbox, and partially transmitted to mass J ₂ , increasing its kinetic energy. The increase in the kinetic energy of the mass J _{2 is} accompanied by a small short-term increase in the angular velocity ω ₂ and the speed of the machine. All this can cause a jerk of the car and a jump in dynamic loads in the transmission.

Switching to a lower gear is characterized by the transfer of kinetic energy from mass J ₂ to mass J ₁ , which leads to a sharp decrease in machine speed, which is also accompanied by high dynamic loads in the transmission.

As a result of slipping of the leading and driven clutch discs accompanying the gear shifting process, the angular velocities ω ₁ and ω ₂ are equalized. Obviously, the switching process will end when the speeds ω ₁ and ω _{2 are} equalized, that is, by the end of the skidding, the angular speeds of the leading and driven parts become equal to ω ₁ = ω ₂ . The ratio of the energy spent on slipping and acceleration (deceleration) of the machine depends on the parameters of the slipping process (the relative sliding speed of the leading and driven disks at the beginning of slipping, the time of slipping, the friction moment of the friction clutches М _ТР ). In this case, a smooth increase in the friction moment M _TP and, accordingly, an increase in the slipping time ensures shock-free gear engagement (see Tractors. Design, construction and calculation: Textbook / I.P. Ksenevich, V.V. Guskov, N.F. Bocharov et al .; Under the general editorship of I.P. Ksenevich. M.: Mechanical Engineering, 1991).

To ensure shock-free gear shifting, devices have been developed that provide a smooth increase in pressure in the boosters of servomotors of friction devices.

The device is taken as a prototype (see V. Petrov. Automatic systems of transport vehicles. - M .: Mashinostroenie, 1974, pp. 80-93. Prototype open publication), used in the system for regulating the smoothness of gear shifting of tracked and wheeled vehicles, containing such basic elements as an internal combustion engine, oil tank, oil pump, electromagnets, spools, friction device, transmission and equipped with Turboglide control system. For a better understanding of the present invention from the entire system, we will consider in more detail a hydraulic accumulator that controls in time the change in the friction moment of the friction element when it is turned on and off and shown in Fig.2.

When fluid is supplied to the cylinder of the friction element, its cavity is quickly filled first and friction surfaces come together, and then the accumulator piston begins to move, compressing the spring. In this case, as the cylinder of the battery is filled and its piston moves, the pressure in the cylinder of the friction element gradually increases in time. For each position of the accumulator piston, pressure

where c is the stiffness of the spring; l is the value of the preliminary compression of the spring; x is the movement of the piston of the battery; ƒ is the area of the piston.

The flow rate determined by the pump output to the battery,

Based on the two previous expressions, the rate of change of pressure over time

The larger ƒ and the lower the flow rate Q, the slower in time the pressure p supplied to the friction element increases, and therefore its friction moment.

However, taking into account the immutability of the adjustments (ƒ value and spring stiffness) of the accumulator considered, it can be noted that devices of this type do not provide a high quality gear shifting process, leading to shock gear shifting and an increase in dynamic loads in the transmission when shifting, and also do not take into account the mode engine operation, driving mode, temperature and viscosity of the oil and the state of the friction device disks.

In this regard, the objective of the present invention is to provide shockless gear shifting and reducing dynamic loads in the transmission when shifting, regardless of engine operation, driving mode, oil temperature and viscosity, as well as the condition of the friction device disks.

This problem is solved through the use of a system for regulating the smoothness of gear shifting of tracked and wheeled vehicles, which ensures the adaptation of the laws of control of the switching process depending on changes in working conditions and the state of friction devices.

Moreover, the system for regulating the smoothness of gear shifting of tracked and wheeled vehicles equipped with an automatic monitoring and control system for the movement of the machine, comprising an internal combustion engine, an oil tank, an oil pump, electromagnets, spools, a friction device, a transmission and characterized in that it contains a second friction device; switching unit; microprocessor control unit; controlled throttle installed in the discharge line between the oil pump and the friction device and having an electrical connection to the output of the switching unit, the input of which is connected to the output of the microprocessor control unit; the outputs of the switching unit through electromagnets are connected to the inputs of the spools, the outputs of which are connected to the inputs of the friction devices. The control system also includes a machine speed sensor associated with the wheel drive; engine speed sensor; an oil pressure sensor in a transmission hydraulic control system having an input from friction devices; the oil temperature sensor in the hydraulic system installed in the discharge line, the outputs of these sensors are connected to the corresponding inputs of the microprocessor control unit.

The invention is illustrated in figures 1, 2 and 3. Figure 3 presents a functional diagram of a system for regulating the smoothness of gear shifting of tracked and wheeled vehicles, which includes the following elements:

1 - oil tank

2 - oil pump;

3 - controlled throttle;

4 - microprocessor control unit;

5 - switching unit;

6 - electromagnet 1;

7 - spool 1;

8 - electromagnet 2;

9 - spool 2;

10 - friction device 1;

11 - friction device 2;

12 - transmission;

13 - internal combustion engine;

14 - engine speed sensor;

15 - speed sensor of the machine;

16 - oil pressure sensor in the hydraulic control system;

17 - oil temperature sensor in the hydraulic system.

The elements are: oil tank 1; oil pump 2; electromagnets 6, 8; spools 7, 9; friction device 10, 11; transmission 12; internal combustion engine 13 - standard.

The controlled throttle 3 is designed to control the pressure in the hydraulic control system. It is a device with a variable bore.

The microprocessor control unit 4 is designed to form a control action based on the processing of the obtained data and determine the missing information on the operating conditions and operating modes of the friction device by calculation. It is an adaptive control system with elements of intellectual information exchange.

The switching unit 5 is intended for amplification and supply to the controlled choke 3 generated by the microprocessor control unit 4 of the control signal. It is a device that converts the signals passing through it.

The engine speed sensor 14 is used to determine the engine speed. It is a sensor that allows you to determine the engine speed and is used in mechanical engineering. A detailed description can be found in the open literature. The use of this sensor will allow you to obtain the necessary information, the processing of which will determine the missing information about the operating modes of the friction device, necessary for the formation of the control action of the microprocessor control unit 4.

The speed sensor of the machine 15 is designed to determine the speed of movement. A detailed description of it can be found in the open literature in connection with the use in mechanical engineering. The use of this sensor will allow you to obtain the required information as a result of the processing of which, using the microprocessor control unit 4, the missing information on the operating conditions and operating modes of the friction device will be determined and a control action on the controlled inductor 3 will be generated.

The oil pressure sensor in the hydraulic control system 16 is designed to determine the oil pressure in the hydraulic control system. It is a standard sensor of the rheostat type used in mechanical engineering. A more complete description of the sensor can be found in the open literature. The use of this sensor will allow the microprocessor control unit 4, processing the information received, to determine the missing information on the operating conditions of the friction device, necessary for the formation of the control action.

The oil temperature sensor in the hydraulic system 17 is designed to determine the temperature of the oil in the hydraulic system. It is a sensor with semiconductor thermal resistance (thermistor) used in mechanical engineering to control the temperature of the coolant in the cooling system. A full description of the design of the sensor can be found in the open literature. The use of this sensor will ultimately ensure a smoother engagement of the gears under any changes in the external conditions and parameters of the systems and units of the machine.

The work of the invention occurs as follows.

When the car moves, the driver holds the fuel control in a position that is inappropriate for ensuring the inclusion of the desired gear. In this case, the signals from the sensors of the rotational speed of the crankshaft of the engine 14, the speed of the machine 15, the oil pressure in the hydraulic control system 16, the oil temperature in the hydraulic system 17 enter the microprocessor control unit 4, where they are processed and a control signal is generated. The signal about the state of the controlled throttle 3 through the feedback channel enters the microprocessor control unit 4.

In the case when the driver moves the fuel supply control body to the position corresponding to ensuring the automatic transmission of the required gear on command from the microprocessor control unit 4, the electromagnet No. 1 6 of the engaged gear is activated, setting the spool No. 1 (7) from the position providing the pumping oil into the servomotor booster friction device No. 1 10 to a position that provides drainage of oil from the booster of the servomotor of friction device No. 1 10, the transmission is turned off. Then, on command from the microprocessor control unit 4, an electromagnet No. 2 8 is triggered, which provides oil access to the booster of the servomotor of the friction device No. 2 11. At the same time, the pressure rise rate determines the rate of increase of the friction moment of the friction device disks

where μ is the friction coefficient of friction discs;

F _SJ - compression force of clutch discs;

r _E is the radius of action of the friction force, equivalent to the action of all elementary friction forces on the contact area of the friction pair;

z is the number of friction pairs.

The total force F _SJ compressing the friction clutch is the algebraic sum of the three terms

where F _C is the static compression force of the disks;

F _C - centrifugal force;

F _VP - the power of the return springs.

The static compressive force of the disks F _{C is} provided by the force of the slave servomotor of the friction clutch developed on its piston due to the action of the static pressure of the working fluid

where p _c is the static oil pressure;

S _P - the area of the pressure disk.

Given the expressions (1), (2), (3) we obtain the friction moment M _TP

Along with the compression force, the friction coefficient μ also varies with instability during operation of the friction device, which varies significantly during slipping. This change depends on the specific pressure q on the surfaces of the disks, the temperature of the disks T _D , the relative sliding speed, the degree of wear of the disks, oil temperature, oil viscosity and other factors.

The problem lies in the difficulty of obtaining information about the parameters characterizing the gear shift process.

Information obtained by direct measurement - from the sensors of the crankshaft of the engine 14, the speed of the machine 15, the oil pressure in the hydraulic control system 16, the oil temperature in the hydraulic system 17, is transmitted to the microprocessor control unit 4. As a result of processing the received data and performing the identification procedure, it is determined missing information on the operating conditions and operating modes of the friction device, necessary for the formation of the control action, which is amplified in the commutator tion 5 and fed to the controllable choke 3, provided in accordance with this control signal, a smooth increase in the pressure booster device includes servo friction transmission, while providing a shock-free switch.

Ensuring shock-free transmission is carried out by regulating a smooth increase in the friction moment of the friction device M _TP by changing the pressure in the hydraulic control system.

The change in pressure in the hydraulic control system is carried out by installing a controlled throttle, while the pressure is controlled by changing the flow area of the throttle.

Thus, the proposed system for regulating the smoothness of gear shifting of tracked and wheeled vehicles has the following advantages compared to the prototype:

shockless gear shifting is ensured under any changes in external conditions, operating modes, and parameters of machine systems and units;

reduced dynamic loads in the transmission when shifting gears.

Claims (1)

A gearshift control system for tracked and wheeled vehicles equipped with an automatic machine motion control system containing an internal combustion engine, an oil tank, an oil pump, electromagnets, spools, a friction device, a transmission, characterized in that it contains a second friction device, a switching unit Microprocessor control unit controlled by a throttle installed in the discharge line between the oil pump and friction devices and having electronic the electrical connection with the output of the switching unit, the input of which is connected to the output of the microprocessor control unit, while the outputs of the switching unit are connected via electromagnets to the inputs of the spools, the outputs of which are connected to the inputs of the friction devices, the control system also contains a vehicle speed sensor associated with the wheel drive, an engine speed sensor, an oil pressure sensor in a transmission hydraulic control system having an input from friction devices, an oil temperature sensor and a hydraulic system installed in the pressurizing line, the outputs of said sensors connected to respective inputs of the microprocessor control unit.

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