Rotary motor starting control system and method

Abstract

The invention discloses a rotary motor starting control system and method, which can realize real-time matching of pump output flow and rotary motor demand flow in a rotary starting process and solve the problem of secondary acceleration or overflow loss and heating caused by mismatching of the pump output flow and the motor demand flow in the rotary starting process. Furthermore, the output flow of the pump is controlled to be transited at the acceleration tail end, so that the problems of overspeed and air suction of the motor when the acceleration tail end is rotationally started are prevented. The structure of the overflow valve of the rotary motor is optimized, the taper angle is reduced, the pressure is kept stable under the smaller overflow amount, the flow needed in the rotary starting process is further reduced, the energy-saving effect is improved, and the problems of energy loss and heating caused by overflow are solved.

Description

Technical Field

[0001] The invention relates to a rotary motor starting control system and method, belonging to the technical field of engineering machinery. Background Art

[0002] Engineering machinery with hydraulic slewing mechanisms, such as excavators, have high requirements for work efficiency and frequent slewing operations, requiring rapid slewing start and fast acceleration. During the slewing start of the excavator, due to the large moment of inertia of the upper body, the starting process usually maintains the maximum torque, that is, the slewing motor maintains the maximum pressure - overflow pressure. In order to maintain the motor overflow state, the pump output flow rate during the starting acceleration process must be greater than the motor demand flow rate, so that the slewing motor continues to overflow and provide the maximum torque to start the upper body. Therefore, there is motor overflow loss and heat during the starting process.

[0003] When the upper body reaches a certain speed and basically matches the input flow, the motor inlet pressure drops rapidly. Due to the sudden change in rotational acceleration, the upper body may overspeed and the rotation motor may suck air, which will give the driver a bad driving experience and may even affect the life of the motor in severe cases.

[0004] Therefore, the maximum pressure of the motor during the starting process is achieved by the motor overflow valve. When the overflow valve passes a stable flow, the pressure can be maintained at a stable value. However, when the flow rate continues to drop to a certain value, the overflow valve cannot maintain the pressure stability, begins to oscillate, and cannot work stably. Those skilled in the art are in urgent need of solving the technical problems during the starting of the swing motor. Summary of the invention

[0005] Purpose: In order to overcome the deficiencies in the prior art, the present invention provides a rotary motor starting control system and method.

[0006] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is:

[0007] In a first aspect, a rotary motor starting control system includes: a rotary motor, wherein an oil port A of the rotary motor is also connected to an oil inlet of a first overflow valve, an oil outlet of the first overflow valve is connected to an oil port B of a reversing valve, an oil port B of the rotary motor is also connected to an oil inlet of a second overflow valve, and an oil outlet of the second overflow valve is connected to an oil port A of the reversing valve.

[0008] Among them, the first overflow valve and the second overflow valve both include: a valve body, a valve cavity is arranged in the valve body, a lifting valve core is axially slidably arranged in the valve cavity, a cone is arranged at the oil inlet position of the lifting valve core, and a lifting valve seat is arranged at the sealing position of the cone; an oil inlet is arranged on the lifting valve seat and is connected with the valve core; an oil outlet is arranged on the side of the valve body close to the lifting valve seat, and when the lifting valve core is separated from the lifting valve seat, the oil outlet is connected.

[0009] A spring is arranged on the outside of the lifting valve core, the right end of the spring is limited by the step surface of the lifting valve core, a spring seat is arranged on the left end of the spring, an adjusting screw plug is arranged on the left end of the spring seat, the adjusting screw plug is fixed to the valve body through a threaded connection, a locking nut is arranged on the outside of the adjusting screw plug through a threaded connection, and the right end face of the locking nut is limited by the left end face of the valve body.

[0010] A buffer valve core is arranged between the adjusting screw plug and the lifting valve core, on the left side of the spring seat, a bushing is arranged between the left cylindrical surface of the buffer valve core and the adjusting screw plug, a plug is arranged on the left side of the bushing, a first O-ring is arranged between the plug and the adjusting screw plug, and a second O-ring is arranged on the outside of the valve body.

[0011] As a preferred solution, it also includes: an engine, a main pump, a reversing valve, a variable system and a controller.

[0012] Among them, the engine is used to drive the main pump, the oil inlet of the main pump is connected to the oil tank, the oil outlet of the main pump is connected to the oil port P of the reversing valve, the swash plate of the main pump is connected to the output end of the variable system, and the input end of the variable system is connected to the controller.

[0013] The oil port T of the reversing valve is connected to the oil tank, the oil port A of the reversing valve is connected to the oil port A of the rotary motor, the oil port B of the reversing valve is connected to the oil port B of the rotary motor, and the output of the rotary motor is connected to the rotary mechanism.

[0014] As a preferred solution, the opening angle of the front end of the cone mouth is 30°-60°.

[0015] As a preferred solution, it also includes an oil replenishment source, which is also connected to the oil port A of the rotary motor and the oil port B of the rotary motor respectively.

[0016] As a preferred solution, it also includes a first one-way valve and a second one-way valve. The first one-way valve is arranged between the oil replenishment source and the oil port A of the rotary motor, and the second one-way valve is arranged between the oil replenishment source and the oil port B of the rotary motor.

[0017] As a preferred solution, a third overflow valve is further included, the oil outlet of the main pump is also connected to the oil inlet of the third overflow valve, and the oil outlet of the third overflow valve is also connected to the oil tank.

[0018] In a second aspect, a control method of a rotary motor starting control system specifically includes:

[0019] When the operating handle is turned to start, the main pump target control signal is obtained from the handle stroke, the engine speed and handle stroke in the current gear are identified, the upper body target speed is calculated, and the upper body speed is collected in real time.

[0020] The real-time rotation speed of the upper body is compared with the target rotation speed of the upper body. If the rotation speed of the upper body is lower than a first threshold of the target rotation speed of the upper body, the main pump outputs in real time according to the output flow of the main pump.

[0021] Among them, the main pump output flow expression is as follows:

[0022] Main pump output flow = corresponding flow of rotary motor + motor overflow + other leakage losses

[0023] In the formula, the corresponding flow of the swing motor = upper body speed × transmission ratio × motor displacement.

[0024] When the upper body speed reaches the first threshold of the upper body target speed, the size m and slope k of the main pump target control signal at the current time are identified. Within the transition time t, the size m of the main pump real-time control signal increases to the target value according to the quadratic curve.

[0025] The quadratic curve expression is as follows:

[0026]

[0027] y is the target control signal of the main pump, x is the time, , , ' are the parameters of the quadratic curve respectively.

[0028] As a preferred solution, the parameters of the quadratic curve are , , The method of obtaining is as follows:

[0029] Get the initial value, including transition start time x1, transition end time x1+t, control signal initial value m, target control signal n, initial slope k, and end slope 0.

[0030] Substituting the initial values ​​into the quadratic curve expression and the expression of the first-order derivative of the quadratic curve, we get , , ' value.

[0031] As a preferred solution, the first threshold is set to 70%-90%.

[0032] As a preferred solution, the transition time t is 0.5s-1.5s.

[0033] Beneficial effects: The present invention provides a rotary motor starting control system and method, which can achieve real-time matching of the pump output flow rate and the rotary motor required flow rate during the rotary starting process, and solve the secondary acceleration problem or overflow loss and heating problem caused by the mismatch between the rotary starting pump output flow rate and the motor required flow rate. Furthermore, the pump output flow rate transition is controlled at the end of acceleration to prevent the motor from overspeeding and sucking air at the end of rotary starting acceleration. The rotary motor overflow valve structure is optimized to reduce the cone angle, so as to maintain pressure stability at a smaller overflow rate, further reduce the required flow rate during the rotary starting process, increase energy saving effects, and reduce energy losses and heating problems caused by overflow.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] (1) Reduce the difficulty of excavator swing start debugging, without the need for repeated debugging and modification under various working conditions, and avoid the situation where the same flow acceleration curve is difficult to meet different working conditions.

[0036] (2) Adapt the starting speed and acceleration of different working conditions to meet the matching between flow and motor speed, ensure sufficient flow during acceleration, maintain the maximum output torque of the motor, and improve operating efficiency.

[0037] (3) A flow transition curve is set at the end of acceleration to ensure a smooth transition of the vehicle body acceleration, increase the driver's driving comfort, reduce motor air intake, and increase the life of the swing motor.

[0038] (4) Reduce overflow loss during motor acceleration to achieve further energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of the rotary motor control system of the present invention.

[0040] Figure 2 It is a schematic diagram of the structure of the overflow valve in the rotary motor.

[0041] Figure 3 It is a schematic flow chart of the control method of the present invention.

[0042] Figure 4 is a schematic diagram of the control curve of the control method, where: Figure 4 (a) is a schematic diagram of the control curve of the prior art. Figure 4 (b) is a schematic diagram of the control curve of the present invention. DETAILED DESCRIPTION

[0043] The following is a clear and complete description of the technical solutions in the examples of the present invention in conjunction with the accompanying drawings in the examples of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present invention.

[0044] The present invention will be further described below in conjunction with specific embodiments.

[0045] Embodiment 1:

[0046] This embodiment introduces a rotary motor starting control system. Figure 1 As shown, it includes: an engine, a main pump, a reversing valve, a rotary motor, a variable system, and a controller.

[0047] Among them, the engine is used to drive the main pump, the oil inlet of the main pump is connected to the oil tank, the oil outlet of the main pump is connected to the oil port P of the reversing valve, the swash plate of the main pump is connected to the output end of the variable system, and the input end of the variable system is connected to the controller.

[0048] The oil port T of the reversing valve is connected to the oil tank, the oil port A of the reversing valve is connected to the oil port A of the rotary motor, the oil port B of the reversing valve is connected to the oil port B of the rotary motor, and the output of the rotary motor is connected to the rotary mechanism.

[0049] The oil port A of the rotary motor is also connected to the oil inlet of the first overflow valve 1, the oil outlet of the first overflow valve 1 is connected to the oil port B of the reversing valve, the oil port B of the rotary motor is also connected to the oil inlet of the second overflow valve 2, and the oil outlet of the second overflow valve 2 is connected to the oil port A of the reversing valve.

[0050] Among them, Figure 2 As shown, the first relief valve 1 and the second relief valve 2 both include: a valve body 101, a valve cavity is arranged in the valve body 101, a lift valve core 102 is axially slidably arranged in the valve cavity, a cone mouth is arranged at the oil inlet position of the lift valve core 102, and a lift valve seat 103 is arranged at the sealing position of the cone mouth; an oil inlet is arranged on the lift valve seat 103 and is connected with the valve core; an oil outlet is arranged on the side of the valve body 101 close to the lift valve seat 103, and when the lift valve core 102 is separated from the lift valve seat 103, the oil outlet is connected.

[0051] A spring 104 is arranged on the outside of the lifting valve core 102, and the right end of the spring 104 is limited by the step surface of the lifting valve core 102. A spring seat 105 is arranged on the left end of the spring 104, and an adjusting screw plug 111 is arranged on the left end of the spring seat 105. The adjusting screw plug 111 is fixed to the valve body 101 through a threaded connection. A locking nut 109 is arranged on the outside of the adjusting screw plug 111 through a threaded connection, and the right end face of the locking nut 109 is limited by the left end face of the valve body 101.

[0052] A buffer valve core 110 is arranged between the adjusting screw plug 111 and the lifting valve core 102, on the left side of the spring seat 105, a bushing 106 is arranged between the left cylindrical surface of the buffer valve core 110 and the adjusting screw plug 111, a plug 107 is arranged on the left side of the bushing 106, a first O-ring 108 is arranged between the plug 107 and the adjusting screw plug 111, and a second O-ring 112 is arranged on the outside of the valve body 101.

[0053] Furthermore, in order to increase the stability of the motor overflow valve at small flow rates, the opening angle of the front end of the cone mouth is 30°-60°, preferably 40°, which increases the valve core opening at small flow rates and increases the stability of the overflow valve at small flow rates. At the same time, the maximum stroke of the lifting valve core is appropriately increased to ensure the flow capacity at large flow rates and reduce the minimum overflow volume for maintaining a stable pressure, that is, to reduce the pump demand flow rate and reduce power loss.

[0054] Furthermore, it also includes an oil replenishment source 3, and the oil replenishment source 3 is also connected to the oil port A of the rotary motor and the oil port B of the rotary motor respectively.

[0055] Furthermore, it also includes a first one-way valve 4 and a second one-way valve 5. The first one-way valve 4 is arranged between the oil replenishment source 3 and the oil port A of the rotary motor, and the second one-way valve 5 is arranged between the oil replenishment source 3 and the oil port B of the rotary motor.

[0056] Furthermore, it also includes a third overflow valve 6, the oil outlet of the main pump is also connected to the oil inlet of the third overflow valve 6, and the oil outlet of the third overflow valve 6 is also connected to the oil tank.

[0057] Furthermore, the main pump is an electrically controlled variable displacement pump.

[0058] Furthermore, a speed sensor integrated in the controller or an external speed sensor is used to collect the speed of the excavator body in real time.

[0059] Furthermore, taking an excavator as an example, the upper body of the excavator is connected to the lower body by a slewing support, and the slewing motor is fixed on the upper body, and the upper body is driven by the slewing motor to slew. The left and right slewing is determined by the reversing of the reversing valve controlled by the handle, wherein when the handle is in the middle position, the reversing valve is in the middle position, and the oil ports A, B, P and T of the reversing valve are all cut off. When the handle is in the left turn, the reversing valve is in the left position, the oil port P of the reversing valve is connected to the oil port A, and the oil port B is connected to the oil port T. When the handle is in the right turn, the reversing valve is in the right position, the oil port P of the reversing valve is connected to the oil port B, and the oil port A is connected to the oil port T. The outlet of the main pump is connected to the inlet of the slewing motor through the reversing valve, the main pump is driven by the engine, and the flow of the main pump is controlled in real time by the controller.

[0060] Example 2

[0061] This embodiment introduces a control method for a rotary motor starting control system. Figure 3 As shown, specifically including:

[0062] When the slewing mechanism starts and the handle is moved, the handle stroke gives the main pump target control signal, identifies the engine speed and handle stroke in the current gear, calculates the main pump output flow, and calculates the upper body target speed, and collects the upper body speed in real time.

[0063] The real-time speed of the upper body is compared with the target speed of the upper body. If the speed of the upper body is lower than the first threshold of the target speed of the upper body, the corresponding flow of the swing motor is calculated according to formula (1), and the output flow of the main pump is calculated according to formula (2). The minimum overflow flow of the swing motor to maintain a stable overflow pressure is added, and the motor leakage and other leakage losses are added to obtain the total required flow, that is, the output flow of the main pump.

[0064] The corresponding flow of the swing motor = the upper body speed × transmission ratio × motor displacement (1)

[0065] Main pump output flow = corresponding flow of rotary motor + motor overflow + other leakage losses (2)

[0066] According to the identified current engine speed, the correspondence between the main pump target control signal and the motor displacement enables the main pump to output in real time according to the main pump output flow rate.

[0067] When the upper body speed reaches the first threshold of the upper body target speed, the magnitude m and slope k of the main pump target control signal at the current time are identified, and the transition time t is set. Within the transition time t, the main pump target control signal increases to the target value according to the quadratic curve (parabola), as shown in Formula 3:

[0068] (3)

[0069] y is the target control signal of the main pump, x is the time, , , ' are the parameters of the quadratic curve respectively.

[0070] First, derive the quadratic curve equation 3 to obtain equation 4:

[0071] (4)

[0072] Let x1 be the transition start time, and x1+t be the transition end time. The initial value of the control signal is m, the target control signal is n, the initial slope is k, and the end slope is 0.

[0073] Substitute the initial parameters into equation 3 and equation 4 to obtain the solution. , , The value of ' is obtained, that is, the control signal transition curve formula is obtained.

[0074] The quadratic curve is used to make the current main pump displacement control signal smoothly transition to the target value, control the flow increase speed, and make the upper body smoothly transition to the target speed without air suction, acceleration mutation and reverse, thereby improving driving experience, reducing motor impact, and increasing motor life, while having no obvious impact on operating efficiency.

[0075] Further, such as Figure 4 As shown in (a) and (b), a represents the inlet pressure curve of the rotary motor, b represents the pump displacement control signal curve, c represents the upper body speed curve, d represents the upper body rotary acceleration curve, and t represents the control signal transition time. Figure 4 (a) describes the characteristics of the original scheme at the end of the whole machine rotation start. The control signal of the original scheme is directly converted into the target signal at the end of the start, so that the control flow is directly converted into the target flow. Under the action of the whole machine inertia, the speed of the rotating part overshoots, causing the inlet pressure to drop overshoot or even suction (pressure drops to 0bar), and the acceleration fluctuates in the opposite direction. After the improvement of this scheme, the effect is as follows Figure 4 As shown in (b), a quadratic curve transition is performed at the end of the swing start to avoid speed overshoot of the upper body, so that the inlet pressure drops without overshoot, the acceleration has no reverse fluctuation, and the upper body stably reaches the target speed, enhancing the comfort of the driver.

[0076] Furthermore, the first threshold is set to 70%-90%, which is determined on different devices based on actual conditions.

[0077] Furthermore, the transition time t is between 0.5s and 1.5s, and is determined on different devices according to actual conditions.

[0078] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A rotary motor starting control system, characterized in that: The invention comprises: a rotary motor; the oil port A of the rotary motor is also connected to the oil inlet of the first overflow valve, the oil outlet of the first overflow valve is connected to the oil port B of the reversing valve, the oil port B of the rotary motor is also connected to the oil inlet of the second overflow valve, and the oil outlet of the second overflow valve is connected to the oil port A of the reversing valve; Wherein, the first relief valve and the second relief valve both comprise: a valve body, a valve cavity is arranged in the valve body, a lifting valve core is axially slidably arranged in the valve cavity, a cone is arranged at the oil inlet of the lifting valve core, and a lifting valve seat is arranged at the sealing position of the cone; an oil inlet is arranged on the lifting valve seat and is connected with the valve core; an oil outlet is arranged on the side of the valve body close to the lifting valve seat, and when the lifting valve core is separated from the lifting valve seat, the oil outlet is connected; A spring is arranged on the outside of the lifting valve core, the right end of the spring is limited by the step surface of the lifting valve core, a spring seat is arranged on the left end of the spring, an adjusting screw plug is arranged on the left end of the spring seat, the adjusting screw plug is fixed to the valve body through a threaded connection, a locking nut is arranged on the outside of the adjusting screw plug through a threaded connection, and the right end face of the locking nut is limited by the left end face of the valve body; A buffer valve core is arranged between the adjusting screw plug and the lifting valve core, on the left side of the spring seat, a bushing is arranged between the left cylindrical surface of the buffer valve core and the adjusting screw plug, a plug is arranged on the left side of the bushing, a first O-ring is arranged between the plug and the adjusting screw plug, and a second O-ring is arranged on the outside of the valve body.

2. A rotary motor starting control system according to claim 1, characterized in that: Also includes: Engine, main pump, reversing valve, variable system and controller; The engine is used to drive the main pump, the oil inlet of the main pump is connected to the oil tank, the oil outlet of the main pump is connected to the oil port P of the reversing valve, the swash plate of the main pump is connected to the output end of the variable system, and the input end of the variable system is connected to the controller; The oil port T of the reversing valve is connected to the oil tank, the oil port A of the reversing valve is connected to the oil port A of the rotary motor, the oil port B of the reversing valve is connected to the oil port B of the rotary motor, and the output of the rotary motor is connected to the rotary mechanism.

3. A rotary motor starting control system according to claim 1 or 2, characterized in that: The opening angle of the front end of the cone mouth is 30°-60°.

4. A rotary motor starting control system according to claim 1 or 2, characterized in that: It also includes an oil replenishment source, which is also connected to the oil port A and the oil port B of the rotary motor respectively.

5. A rotary motor starting control system according to claim 4, characterized in that: It also includes a first one-way valve and a second one-way valve. The first one-way valve is arranged between the oil replenishment source and the oil port A of the rotary motor, and the second one-way valve is arranged between the oil replenishment source and the oil port B of the rotary motor.

6. A rotary motor starting control system according to claim 1 or 2, characterized in that: It also includes a third overflow valve, the oil outlet of the main pump is also connected to the oil inlet of the third overflow valve, and the oil outlet of the third overflow valve is also connected to the oil tank.

7. A control method for a rotary motor starting control system according to any one of claims 1 to 6, characterized in that: Specifically include: When the operating handle is turned to start, the handle stroke is identified, the main pump target control signal is obtained from the handle stroke, the engine speed in the current gear is identified, the upper body target speed is calculated, and the upper body speed is collected in real time; The real-time rotation speed of the upper body is compared with the target rotation speed of the upper body. If the rotation speed of the upper body is lower than the first threshold of the target rotation speed of the upper body, the main pump outputs in real time according to the output flow of the main pump; Among them, the main pump output flow expression is as follows: Main pump output flow = corresponding flow of rotary motor + motor overflow + other leakage losses In the formula, the corresponding flow of the swing motor = upper body speed × transmission ratio × motor displacement; When the upper body speed reaches the first threshold of the upper body target speed, the magnitude m and slope k of the main pump target control signal at the current time are identified, and within the transition time t, the magnitude m of the main pump real-time control signal increases to the target value according to the quadratic curve; The quadratic curve expression is as follows: ； y is the real-time control signal of the main pump, x is the time, , , ' are the parameters of the quadratic curve respectively.

8. The control method according to claim 7, characterized in that: The parameters of the quadratic curve , , The method of obtaining is as follows: Get the initial value, including transition start time x1, transition end time x1+t, control signal initial value m, target control signal n, initial slope k, and end slope 0; Substituting the initial values ​​into the quadratic curve expression and the expression of the first-order derivative of the quadratic curve, we get , , ' value.

9. The control method according to claim 7, characterized in that: The first threshold is set to 70%-90%.

10. The control method according to claim 7, characterized in that: The transition time t is 0.5s-1.5s.

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