Hydraulic retarder oil charging and discharging control method and system, storage medium and software product

Abstract

The invention discloses a hydraulic retarder oil charging and discharging control method and system, a storage medium and a software product. According to the scheme, four switch type electromagnetic valves are used for controlling oil charging and discharging work of the retarder, pressure closed-loop control, gas consumption pre-calculation control and direct exhaust control are set in the control method, and in the process, according to a target oil charging amount instruction and information such as the current air pressure value in an oil tank obtained by a sensor, the oil charging amount is calculated. And determining to execute a pressure closed-loop control method or a gas consumption pre-calculation control method. According to the invention, the response speed of oil charging and discharging control can be improved, and the control precision of vehicle braking is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to vehicle pressure system control technology, in particular to a hydraulic retarder oil filling and discharging control method and system based on on-off electromagnetic valves. BACKGROUND

[0002] The hydraulic retarder is an auxiliary braking device widely used in large commercial vehicles. Its working principle is to fill oil into its working cavity to generate braking force to slow down the vehicle, and to discharge the oil in the working cavity to eliminate the braking force. The adjustment of the size of the retarder braking force is essentially the adjustment of the oil filling and discharging in its working cavity. At present, the oil filling and discharging control of the hydraulic retarder is realized by controlling the input current of the proportional electromagnetic valve. The proportional electromagnetic valve can continuously adjust the oil filling amount in the working cavity of the retarder according to the size of the control input current, so as to realize different braking forces. However, the proportional valve needs to be powered all the time when the existing retarder is working, which leads to a high failure rate. SUMMARY

[0003] In view of the defects or deficiencies of the prior art, the present application provides a hydraulic retarder oil filling and discharging control method based on on-off electromagnetic valves.

[0004] The present application relates to the amount of oil filling and discharging in the pressure cavity of the hydraulic retarder, which is controlled by regulating the amount of entering and discharging gas in the oil tank connected thereto. The first large flow on-off electromagnetic valve and the first small flow on-off electromagnetic valve are provided on the gas inlet path of the oil tank, and the first large flow on-off electromagnetic valve and the first small flow on-off electromagnetic valve are connected in parallel. The second large flow on-off electromagnetic valve and the second small flow on-off electromagnetic valve are provided on the gas outlet path of the oil tank, and the second large flow on-off electromagnetic valve and the second small flow on-off electromagnetic valve are connected in parallel. The method controls the opening and closing of each on-off electromagnetic valve according to the target pressure value in the oil tank to realize the control of the pressure cavity oil filling and discharging. The method comprises: obtaining the target pressure value in the oil tank; collecting the actual pressure value in the oil tank P i , and calculating the pressure difference between the target pressure value P and the actual pressure value P i ∆P i , P i the actual pressure value collected at the current time i , the actual pressure value collected at the current time ∆P i = P - P i , and each pressure value is in bar ; if P≠0 and ∆P i ​=0 If yes, continue to acquire the target pressure value, P ≠ 0 and ΔP i >0 If yes, execute the oil filling control, P ≠ 0 and ∆P i <0 If yes, execute the oil discharging control, P=0 If yes, execute the emptying control; The oil filling control comprises: Step 11, calculating the pressure in the pressure chamber by using formula (1)-(3) P i to P the required time length :

[0005]

[0006]

[0007] In the formula, is the pressure value in the oil tank and the corresponding air volume conversion formula; 1 atm represents 1 standard atmospheric pressure; and are the gas flow rates when the first large flow switch electromagnetic valve and the first small flow switch electromagnetic valve are opened, respectively, with the unit being L / min; Step 12, controlling the opening and closing of each electromagnetic valve according to formula (4)-(7):

[0008]

[0009]

[0010]

[0011] Among them: , is a control parameter; is the input duty cycle of the first large flow switch electromagnetic valve, is the input duty cycle of the first small flow switch electromagnetic valve, is the input duty cycle of the second large flow switch electromagnetic valve, is the input duty cycle of the second small flow switch electromagnetic valve; is a time coefficient, ; is the sampling period of the actual pressure value in the oil tank; The oil discharging control comprises: Step 21, the pressure in the pressure chamber is calculated by using formula (8)-(10) P i decreased to P the time required :

[0012]

[0013]

[0014] wherein, and are the gas flow rates when the second large flow switch electromagnetic valve and the second small flow switch electromagnetic valve are opened, respectively; Step 22, the opening and closing of each electromagnetic valve is controlled according to formula (11)-(14):

[0015]

[0016]

[0017]

[0018]

[0019] wherein, is the input duty ratio of the first large flow switch electromagnetic valve, is the input duty ratio of the first small flow switch electromagnetic valve, is the input duty ratio of the second large flow switch electromagnetic valve, is the input duty ratio of the second small flow switch electromagnetic valve; is a time coefficient, ; The emptying control includes the opening and closing of each electromagnetic valve controlled according to formula (15)-(18):

[0020]

[0021]

[0022]

[0023] wherein, is the input duty ratio of the first large flow switch electromagnetic valve, is the input duty ratio of the first small flow switch electromagnetic valve, is the input duty ratio of the second large flow switch electromagnetic valve, The input duty cycle of the second small flow switch solenoid valve.

[0024] The optional solution is, .

[0025] The application also provides a related hydraulic retarder oil charging and discharging control system, which comprises a controller, a first large flow switch solenoid valve and a first small flow switch solenoid valve arranged on an oil tank air inlet gas path, and a second large flow switch solenoid valve and a second small flow switch solenoid valve arranged on an oil tank air outlet gas path, and the first large flow switch solenoid valve and the first small flow switch solenoid valve are connected in parallel, and the second large flow switch solenoid valve and the second small flow switch solenoid valve are connected in parallel; the controller controls the opening and closing of each switch solenoid valve according to the target pressure value in the oil tank to realize the control of the oil charging and discharging of the pressure cavity.

[0026] The application also provides a corresponding storage medium and a software product, the storage medium stores a computer program / instruction, and the computer program / instruction is executed by a processor to realize the steps of the above method. The software product comprises a computer program / instruction, and the computer program / instruction is executed by a processor to realize the steps of the above method.

[0027] The application solves the problems of high cost and high failure rate of the solenoid valve by using the switch solenoid valve to replace the proportional solenoid valve, and solves the problem of low brake control precision caused by the slow retarder oil charging and discharging process by using the pressure-based closed-loop control and the gas consumption pre-calculation method.

[0028] The application controls the retarder oil charging and discharging work by using four switch solenoid valves, realizes the air charging and discharging into the retarder oil tank at different speeds by controlling the opening and closing of the four solenoid valves, and realizes the oil charging and discharging into the retarder pressure cavity at different speeds. When the switch solenoid valve is used for oil charging and discharging control, the method sets the pressure closed-loop control, the gas consumption pre-calculation control and the direct air discharge control, and determines to execute the pressure closed-loop control method or the gas consumption pre-calculation control method according to the target oil charging amount instruction and the current air pressure value in the oil tank obtained by the sensor and other information. The application can improve the response speed of the oil charging and discharging control, and further improve the control precision of the vehicle brake. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The figure is a schematic diagram of the principle of the retarder system involved in the application. DETAILED DESCRIPTION

[0030] Unless otherwise specified, the scientific and technical terms in the present application are understood according to the understanding of the relevant persons skilled in the art. The application is further described in detail below by means of specific embodiments and in conjunction with the drawings.

[0031] AsFigure 1 As shown, the oil charging and discharging system of the retarder of the application comprises a retarder pressure cavity 1, a heat exchanger 2, an oil tank 7 and a constant pressure gas source 8; wherein the oil outlet of the oil tank is connected with the oil inlet of the pressure cavity, the oil outlet of the pressure cavity is connected with the oil return port of the oil tank through the heat exchanger, the air inlet of the oil tank is connected with the constant pressure gas source through an air inlet gas path, and the air inlet gas path of the oil tank is provided with a first large flow on-off electromagnetic valve 3 and a second small flow on-off electromagnetic valve 4 in parallel, and the air outlet gas path is provided with a second large flow on-off electromagnetic valve 5 and a first small flow on-off electromagnetic valve 6 in parallel.

[0032] When working, the constant pressure gas source 8 provides constant air pressure for the system, when the air inlet valve (the first large flow on-off electromagnetic valve 3 or / and the second small flow on-off electromagnetic valve 4) is opened, the air outlet valve (the second large flow on-off electromagnetic valve 5 or / and the second small flow on-off electromagnetic valve 6) is kept closed, the high pressure gas enters the retarder oil tank 7 to press the oil in the oil tank into the retarder pressure cavity; when the air outlet valve is opened, the air inlet valve is kept closed at the same time, the high pressure gas in the retarder oil tank is discharged through the air outlet valve, the pressure in the oil tank is reduced, and the oil in the working cavity of the retarder flows back to the oil tank, and the heat exchanger is used for oil cooling in the process. Through the above method, the oil in the working cavity of the retarder is charged and discharged. Meanwhile, a pressure sensor is installed in the retarder oil tank to collect the air pressure value in the oil tank.

[0033] In the control method and system of the application, the large and small flow electromagnetic valves are arranged on the air inlet gas path and the air outlet gas path of the oil tank respectively, in working, the air in the oil tank is quickly entered and discharged through the large flow electromagnetic valve, so as to improve the oil charging and discharging speed in the pressure cavity, improve the response time of the system, use the small flow valve to reduce the control precision caused by the overshoot, oscillation and too long adjustment time of the control system to reach the steady state, considering the compressibility of the gas and the delay problem of the sensor signal, the small flow electromagnetic valve has better effect than the large flow valve in adjusting around the steady state pressure value.

[0034] When the vehicle starts the retarder to brake, the retarder oil charging and discharging control system will receive the target pressure value instruction in the oil tank corresponding to the target oil charging amount sent by the vehicle, the application controls the opening and closing of each on-off electromagnetic valve according to the obtained target pressure value and the collected actual pressure value in the mailbox to control the oil charging and discharging of the pressure cavity, and each electromagnetic valve control uses pulse width modulation (PWM).

[0035] In the method of the application, the pre-air intake time and the pre-air exhaust time are calculated in real time to improve the accuracy and stability of the control.

[0036] In actual use, the target pressure value is determined according to the working condition of the retarder, and generally the working condition of the retarder includes five brake gears, i.e., five target pressure values. For example, the target pressure values are 0.6 bar, 1.2 bar, 1.8 bar, 2.4 bar and 3 bar, which correspond to the 1-5 gears of the retarder brake gears, respectively.

[0037] In an actual scheme, the large-flow range and the small-flow range of the on-off valve on the air outlet path and the on-off valve on the air inlet path are the same, and the range of each valve is determined according to the actual working requirement of the retarder. For example, during the process that the liquid volume of the pressure cavity of the retarder is from 0% to 100%, the volume of the normal-pressure air required is Vmax, and according to the minimum time Tmin required by the vehicle for the retarder to be completely opened, the total flow of the large-flow and small-flow air inlet valves can be determined as Vmax / Tmin, and further, the ranges of the large-flow and small-flow valves on the air inlet path are determined according to a certain proportion, for example, the flow of the large-flow valve is 0.8 times Vmax / Tmin, and the flow of the small-flow valve is 0.2 times Vmax / Tmin.

[0038] In the specific embodiment, the scheme of the present application involves The conversion formula (generally a linear function) of the pressure in the retarder tank and the corresponding air volume obtained through experiments can obtain the air volume in the tank corresponding to the pressure value according to different air pressure values. Specifically, a volume scale can be installed on the tank, and the data of the pressure sensor in the tank and the corresponding volume scale data are tested to obtain the conversion formula. The scheme of the present application involves The controller parameters are obtained by pre-test, and specifically, the parameters can be adjusted by PID, and the parameters are obtained through common tests. The scheme of the present application involves The reference value range is 10-15 or 100-150.

Claims

1. A method for controlling the filling and discharging of oil in a hydraulic retarder, wherein the filling and discharging amounts of oil in the pressure chamber of the hydraulic retarder are controlled by adjusting the amount of gas entering and exiting from an oil tank connected thereto, characterized in that... The oil tank's inlet air path is equipped with a first high-flow solenoid valve and a first low-flow solenoid valve, which are connected in parallel. The oil tank's outlet air path is equipped with a second high-flow solenoid valve and a second low-flow solenoid valve, which are also connected in parallel. The method controls the opening and closing of each solenoid valve according to the target pressure value in the oil tank to control the filling and discharging of the pressure chamber. The method includes: Obtain the target pressure value inside the fuel tank; Collect the actual pressure value inside the oil tank P i And calculate the target pressure value. P Compared with actual pressure value P i pressure difference ∆P i , P i For the current moment i The actual pressure values ​​collected, ∆P i =PP i The units for each pressure value are: bar ; if P≠0 and ∆P i =0 Then continue to obtain the target pressure value. P≠0 and ∆P i >0 Then oil filling control is executed. P≠0 and ∆P i <0 Then execute oil discharge control. P=0 Then execute the venting control; The oil filling control includes: Step 11, use equations (1) to (3) to calculate the pressure inside the cavity. P i Rise to P Duration required : In the formula, This is the formula for converting the pressure value inside the fuel tank to the corresponding air volume; 1 atm represents 1 standard atmosphere. and These are the gas flow rates when the first high-flow-rate solenoid valve and the first low-flow-rate solenoid valve are open, respectively, in L / min. Step 12, control the switching of each solenoid valve according to equations (4) to (7): in: , For control parameters; The input duty cycle of the first high-flow-rate switching solenoid valve. The input duty cycle of the first low-flow-rate switching solenoid valve is... The input duty cycle for the second-largest flow-through switching solenoid valve. The input duty cycle of the second low-flow-rate switching solenoid valve; For time coefficient, ; The sampling period for the actual pressure value inside the oil tank; The oil discharge control includes: Step 21, calculate the pressure inside the pressure cavity using equations (8) to (10). P i Reduce to P Time required : In the formula, and These are the gas flow rates when the second large flow switch solenoid valve and the second small flow switch solenoid valve are open, respectively. Step 22, control the switching of each solenoid valve according to equations (11) to (14): In the formula, The input duty cycle of the first high-flow-rate switching solenoid valve. The input duty cycle of the first low-flow-rate switching solenoid valve is... The input duty cycle for the second-largest flow-through switching solenoid valve. The input duty cycle of the second low-flow-rate switching solenoid valve; For time coefficient, ; The venting control includes controlling the switching of each solenoid valve according to equations (15) to (18): In the formula, The input duty cycle of the first high-flow-rate switching solenoid valve. The input duty cycle of the first low-flow-rate switching solenoid valve is... The input duty cycle for the second-largest flow-through switching solenoid valve. This is the input duty cycle of the second low-flow-rate switching solenoid valve.

2. The hydraulic retarder oil filling and discharging control method according to claim 1, characterized in that, 。 3. A basic hydraulic retarder oil filling and discharging control system, characterized in that, It includes a controller, a first high-flow-rate solenoid valve and a first low-flow-rate solenoid valve installed in the air intake path of the oil tank, and a second high-flow-rate solenoid valve and a second low-flow-rate solenoid valve installed in the air outlet path of the oil tank, wherein the first high-flow-rate solenoid valve and the first low-flow-rate solenoid valve are connected in parallel, and the second high-flow-rate solenoid valve and the second low-flow-rate solenoid valve are connected in parallel. The controller uses the method described in claim 1 or 2 to control the opening and closing of each switch solenoid valve according to the target pressure value in the oil tank, thereby controlling the filling and discharging of oil in the pressure chamber.

4. A storage medium, characterized in that, It stores a computer program / instruction, characterized in that when the computer program / instruction is executed by a processor, it implements the steps of the method described in claim 1 or 2.

5. A software product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method described in claim 1 or 2.

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