A rotary motor starting control system and method

Abstract

This invention discloses a rotary motor starting control system and method, which can achieve real-time matching between the pump output flow and the rotary motor's required flow during the rotary starting process, solving the secondary acceleration problem or overflow loss and heat generation problem caused by the mismatch between the pump output flow and the motor's required flow. Furthermore, the pump output flow is controlled at the end of the acceleration phase to prevent the motor from overspeeding and sucking in air at the end of the rotary starting acceleration. The structure of the rotary motor's overflow valve is optimized, reducing the cone angle to maintain stable pressure with a smaller overflow flow, further reducing the flow required during the rotary starting process, increasing energy saving, and reducing energy loss and heat generation caused by overflow.

Description

Technical Field

[0001] This invention relates to a rotary motor starting control system and method, belonging to the field of engineering machinery technology. Background Technology

[0002] Construction machinery with hydraulic slewing mechanisms, such as excavators, requires high work efficiency, frequent slewing operations, and rapid slewing starts and acceleration. During the excavator's slewing start-up, due to the large rotational inertia of the upper body, the starting process typically maintains maximum torque, i.e., the slewing motor maintains maximum pressure—overflow pressure. To maintain the motor's overflow state, the pump output flow rate during starting and acceleration must exceed the motor's required flow rate, causing the slewing motor to continuously overflow and provide maximum torque to start the upper body. Therefore, there are motor overflow losses and heat generation during the starting process.

[0003] Once the upper body reaches a certain speed and the input flow rate is basically matched, 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 in air, resulting in a poor driving experience for the driver and, in severe cases, affecting the motor's lifespan.

[0004] Therefore, the motor relies on a relief valve to maintain maximum pressure during startup. When the relief valve allows a stable flow, it can maintain a stable pressure. However, when the flow continuously decreases to a certain value, the relief valve can no longer maintain stable pressure and begins to oscillate, failing to operate stably. Those skilled in the art urgently need to solve the technical problems encountered during the startup of rotary motors. Summary of the Invention

[0005] Objective: In order to overcome the shortcomings of the existing technology, 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 as follows:

[0007] In a first aspect, a rotary motor starting control system includes a rotary motor. The oil port A of the rotary motor is also connected to the oil inlet of a first relief valve, the oil outlet of the first relief valve is connected to the oil port B of a directional control valve, the oil port B of the rotary motor is also connected to the oil inlet of a second relief valve, and the oil outlet of the second relief valve is connected to the oil port A of the directional control valve.

[0008] The first overflow valve and the second overflow valve each include: a valve body, a valve cavity provided within the valve body, a lifting valve core axially slidably disposed within the valve cavity, a conical opening provided at the oil inlet position of the lifting valve core, and a lifting valve seat provided at the sealing part of the conical opening; an oil inlet provided on the lifting valve seat and communicating with the valve core; and an oil outlet provided on the side of the valve body near the lifting valve seat, which becomes open when the lifting valve core separates from the lifting valve seat.

[0009] A spring is provided on the outside of the lifting valve core. The right end of the spring is limited by the stepped surface of the lifting valve core. A spring seat is provided on the left end of the spring. An adjusting screw plug is provided on the left end of the spring seat. The adjusting screw plug is fixed to the valve body by a threaded connection. A locking nut is provided on the outside of the adjusting screw plug by a threaded connection. The right end of the locking nut is limited by the left end of the valve body.

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

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

[0012] The engine drives the main pump, the inlet of the main pump is connected to the oil tank, the outlet of the main pump is connected to the port P of the reversing valve, the swashplate of the main pump is connected to the output of the variable system, and the input 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 embodiment, the opening angle of the tapered opening is 30°-60°.

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

[0016] As a preferred embodiment, the system also includes a first check valve and a second check valve. The first check valve is provided between the oil supply source and the oil port A of the rotary motor, and the second check valve is provided between the oil supply source and the oil port B of the rotary motor.

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

[0018] Secondly, a control method for 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 under the current gear are identified, the target speed of the upper body is calculated, and the upper body speed is collected in real time.

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

[0021] The expression for the main pump output flow rate is as follows:

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

[0023] In the formula, the flow rate corresponding to the rotary 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 magnitude m and slope k of the main pump target control signal at the current time are identified. During the transition time t, the magnitude m of the main pump real-time control signal increases to the target value according to a quadratic curve.

[0025] The expression for the quadratic curve is as follows:

[0026]

[0027] y represents the target control signal for the main pump, and x represents time. , , ' represents the parameters of the quadratic curve.

[0028] As a preferred embodiment, the parameters of the quadratic curve , , The method for obtaining it is as follows:

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

[0030] Substituting the initial values ​​into the expression for the quadratic curve and the expression for the first derivative of the quadratic curve, we obtain... , , The value of '.

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

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

[0033] Beneficial Effects: The rotary motor starting control system and method provided by this invention can achieve real-time matching between the pump output flow and the rotary motor's required flow during the rotary starting process, solving the secondary acceleration problem or overflow loss and heat generation problem caused by the mismatch between the pump output flow and the motor's required flow during rotary starting. Furthermore, by controlling the pump output flow transition at the end of acceleration, it prevents the motor from overspeeding and sucking in cavitation at the end of the rotary starting acceleration. The structure of the rotary motor's overflow valve is optimized, reducing the cone angle and achieving stable pressure with a smaller overflow flow, further reducing the flow required during rotary starting, increasing energy saving, and reducing energy loss and heat generation caused by overflow.

[0034] Compared with existing technologies, the advantages of this invention are as follows:

[0035] (1) Reduce the difficulty of excavator slewing start debugging, eliminating the need for repeated debugging and modification under various working conditions, and avoiding the situation where the same flow acceleration curve cannot meet different working conditions.

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

[0037] (3) Set a flow transition curve at the end of acceleration to make the acceleration of the upper body transition smoothly, increase the driver's driving comfort, reduce the motor sucking air phenomenon, and increase the life of the rotary motor.

[0038] (4) Reduce overflow loss during motor acceleration to achieve further energy saving. Attached Figure Description

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

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

[0041] Figure 3 This is a flowchart illustrating the control method of the present invention.

[0042] Figure 4 This is a schematic diagram of the control curve for 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 Implementation

[0043] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0044] The present invention will be further described below with reference to specific embodiments.

[0045] Example 1:

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

[0047] The engine drives the main pump, the inlet of the main pump is connected to the oil tank, the outlet of the main pump is connected to the port P of the reversing valve, the swashplate of the main pump is connected to the output of the variable system, and the input 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 relief valve 1, the oil outlet of the first relief 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 relief valve 2, and the oil outlet of the second relief valve 2 is connected to the oil port A of the reversing valve.

[0050] Among them, such as Figure 2 As shown, both the first overflow valve 1 and the second overflow valve 2 include: a valve body 101, a valve cavity is provided inside the valve body 101, a lifting valve core 102 is axially slidably disposed inside the valve cavity, a conical opening is provided at the oil inlet position of the lifting valve core 102, and a lifting valve seat 103 is provided at the sealing part of the conical opening; an oil inlet is provided on the lifting valve seat 103 and communicates with the valve core; an oil outlet is provided on the side of the valve body 101 near the lifting valve seat 103, and the oil outlet is open when the lifting valve core 102 is separated from the lifting valve seat 103.

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

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

[0053] Furthermore, to increase the stability of the motor relief valve under low flow rate, the opening angle of the front end of the cone is 30°-60°, preferably 40°. This increases the valve core opening under low flow rate, thereby increasing the stability of the relief valve under low flow rate. At the same time, it appropriately increases the maximum stroke of the lifting valve core to ensure the flow capacity under high flow rate, and reduces the minimum overflow flow rate required to maintain stable pressure, which in turn reduces the pump's required flow rate and reduces power loss.

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

[0055] Furthermore, it also includes a first check valve 4 and a second check valve 5. The first check valve 4 is provided between the oil supply source 3 and the oil port A of the rotary motor, and the second check valve 5 is provided between the oil supply 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 connected to the oil inlet of the third overflow valve 6, and the oil outlet of the third overflow valve 6 is connected to the oil tank.

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

[0058] Furthermore, the controller integrates a speed sensor or uses an external speed sensor for real-time acquisition of the excavator's body speed.

[0059] Furthermore, taking an excavator as an example, the excavator's upper body is connected to the lower body by a slewing bearing. The slewing motor is fixed to the upper body and drives its rotation. The directional valve, controlled by a lever, determines left or right rotation. When the lever is in the neutral position, the directional valve is also in the neutral position, and ports A, B, P, and T are all closed. When the lever is turned left, the directional valve is in the left position, with ports P and A connected, and ports B and T connected. When the lever is turned right, the directional valve is in the right position, with ports P and B connected, and ports A and T connected. The main pump outlet is connected to the slewing motor inlet via the directional valve. The main pump is driven by the engine, and its flow rate is controlled in real-time by a controller.

[0060] Example 2

[0061] This embodiment describes a control method for a rotary motor starting control system, such as... Figure 3 As shown, it specifically includes:

[0062] When the slewing mechanism starts and the handle moves, 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, calculates the upper body target speed, and collects the upper body speed in real time.

[0063] Compare the real-time rotation speed of the upper body 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, calculate the corresponding flow rate of the rotary motor according to formula (1) and calculate the output flow rate of the main pump according to formula (2). The minimum overflow flow rate for the rotary motor to maintain stable overflow pressure is increased, and motor leakage and other leakage losses are increased. The total required flow rate is obtained, which is the output flow rate of the main pump.

[0064] The flow rate corresponding to the rotary motor = 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] Based on 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 current main pump target control signal are identified, and a transition time t is set. During the transition time t, the main pump target control signal increases to the target value according to a quadratic curve (parabola), as shown in Equation 3:

[0068] (3)

[0069] y represents the target control signal for the main pump, and x represents time. , , ' represents the parameters of the quadratic curve.

[0070] First, differentiate equation 3 of the conic section to obtain equation 4:

[0071] (4)

[0072] Let x1 be the transition start time, then x1+t is 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 final slope is 0.

[0073] Substituting the initial parameters into Equations 3 and 4, and solving for the results, we obtain... , , The value of ' is used to derive the formula for the control signal transition curve.

[0074] By using a quadratic curve, the current main pump displacement control signal is smoothly transitioned to the target value, controlling the rate of flow increase and ensuring a smooth transition of the upper vehicle body to the target speed. This eliminates phenomena such as air suction, sudden acceleration changes, and reverse rotation, improving the driving experience, reducing motor impact, increasing motor life, and having no significant impact on operating efficiency.

[0075] Furthermore, 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 rotation 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 machine's slewing start-up. In the original scheme, the control signal directly transforms into the target signal at the end of the start-up, causing the control flow rate to directly change to the target flow rate. Under the influence of the machine's inertia, the slewing section experiences speed overshoot, leading to inlet pressure drop overshoot or even cavitation (pressure drops to 0 bar), and acceleration fluctuations in the opposite direction. After the improvement of this scheme, the effect is as follows: Figure 4 As shown in (b), a secondary curve transition is performed at the end of the slewing start to avoid speed overshoot of the upper body, thereby reducing the inlet pressure without overshoot, preventing acceleration from fluctuating in the opposite direction, and allowing the upper body to stably reach the target speed, thus enhancing driver comfort.

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

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

[0078] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A control method for a rotary motor starting control system, characterized in that: The rotary motor starting control system includes: a rotary motor, an engine, a main pump, a reversing valve, a variable system, and a controller; The engine drives the main pump, the inlet of the main pump is connected to the oil tank, the outlet of the main pump is connected to the port P of the reversing valve, the swashplate of the main pump is connected to the output of the variable system, and the input 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. The control method specifically includes: When the operating handle is turned to start, the handle travel is identified, the main pump target control signal is obtained from the handle travel, 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 main pump output flow rate. The expression for the main pump output flow rate is as follows: Main pump output flow = corresponding flow rate of rotary motor + motor overflow + other leakage losses In the formula, the flow rate corresponding to the rotary 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. During the transition time t, the magnitude m of the main pump real-time control signal increases to the target value according to a quadratic curve. The expression for the quadratic curve is as follows: ； y represents the real-time control signal for the main pump, and x represents time. , , ' represents the parameters of the quadratic curve.

2. The control method according to claim 1, characterized in that: The parameters of the conic section , , The method for obtaining it is as follows: Obtain initial values, including transition start time x1, transition end time x1+t, initial value of control signal m, target control signal n, initial slope k, and end slope 0; Substituting the initial values ​​into the expression for the quadratic curve and the expression for the first derivative of the quadratic curve, we obtain... , , The value of '.

3. The control method according to claim 1, characterized in that: The first threshold is set to 70%-90%.

4. The control method according to claim 1, characterized in that: The transition time t is 0.5s-1.5s.

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