CN111577717A - Overflow loss recovery system based on hydraulic motor and control method thereof - Google Patents

Abstract

The invention provides an overflow loss recovery system based on a hydraulic motor, comprising an oil tank, a main pump, a first check valve, a first reversing valve, a first relief valve and a hydraulic cylinder, the first relief valve It has a first valve oil outlet and a pilot oil outlet, the first valve oil outlet is connected with a second reversing valve, and the second reversing valve has a second oil outlet and a second oil inlet, wherein One of the second oil outlets is connected with a hydraulic motor, and the hydraulic motor is driven and connected with a generator. The invention also provides a hydraulic motor-based overflow loss recovery control method. Through the organic combination of the reversing valve, relief valve, check valve, hydraulic motor and generator, etc., the energy recovery of the overflow loss of the relief valve port is realized, and the outlet loss of the relief valve is recovered by using the hydraulic motor and the generator. The hydraulic energy is converted into electric energy to realize energy recovery. Since the generator can be actively controlled, it can solve the pressure difference loss at the valve port to achieve high-efficiency energy recovery.

Description

An overflow loss recovery system based on hydraulic motor and its control method

technical field

The invention relates to an energy-saving control system and a control method thereof, in particular to an overflow loss recovery system based on a hydraulic motor and a control method thereof.

Background technique

The outlet of the proportional relief valve (conventional) is generally connected to the fuel tank, and the relief valve works, and the pressure loss of the valve port is the inlet pressure of the relief valve. The flow varies with the type of hydraulic system. With the trend of high pressure of the hydraulic system, the problem of overflow loss will be more serious. The overflow loss of the overflow valve is related to the type of hydraulic system, the actual working conditions in the working process and the operation mode of the operator. According to the function of the overflow valve, the overflow loss is mainly divided into the pressure regulation overflow loss and the safety overflow loss. In the throttle-in speed regulation and the throttle-out speed regulation circuit, the relief valve functions as a relief and pressure regulation, and some hydraulic oil always returns to the tank through the relief valve, so there is always overflow loss in the relief valve. When the relief valve acts as a safety valve, although the relief valve will work only under certain working conditions, there is also an overflow loss. At present, traditional energy-saving hydraulic drive systems such as positive flow technology, negative flow technology, and load-sensing technology belong to the flow coupling system. Although the energy utilization rate of hydraulic excavators can be improved to some extent, it is more to solve the problem of hydraulic system energy consumption. The problem of flow loss, or by optimizing the matching of the flow, reduces the flow through the overflow valve port as much as possible, and does not fundamentally solve the problem of overflow loss of the overflow element itself.

The Chinese invention patent publication number CN106122188B discloses a hydraulic accumulator-based conventional overflow valve overflow loss recovery and reuse system, which is a system designed by the applicant in the early days, which uses a hydraulic accumulator for energy storage. Although the overflow loss problem of the overflow element itself can be solved under certain conditions, because the pressure of the accumulator cannot be actively controlled, in the proportional overflow valve whose target pressure will be dynamically adjusted, the pressure difference at the overflow valve port If it cannot be set according to the minimum pressure difference, there is still a certain pressure loss at the valve port, which makes it difficult to achieve efficient energy recovery.

In view of this, the applicant has conducted in-depth research on the above-mentioned problems, and this case came into being.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an overflow sleep recovery system based on a hydraulic motor and a control method thereof, which can solve the pressure difference loss at the valve port to realize high-efficiency energy recovery.

In order to achieve the above object, the present invention adopts the following technical solutions:

An overflow loss recovery system based on a hydraulic motor, comprising an oil tank, a main pump whose oil inlet is connected to the oil tank, a first check valve whose oil inlet is connected to an oil outlet of the main pump, and an oil inlet a first reversing valve and a first relief valve respectively connected with the oil outlet of the first one-way valve, and a hydraulic cylinder connected with the first reversing valve, the first reversing valve has a first An oil discharge port and two first oil outlets, one of the first oil outlet is communicated with the rod cavity of the hydraulic cylinder, and the other first oil outlet is connected with the rodless cavity of the hydraulic cylinder The first oil discharge port is communicated with the oil tank, the first relief valve has a first valve oil outlet and a pilot oil outlet communicated with the oil tank, and the first valve oil outlet is connected to the oil tank. There is a second reversing valve, the second reversing valve has two second oil outlets and a second oil inlet which is communicated with the oil outlet of the first valve, and one of the second oil outlets is connected There is a hydraulic motor, the other second oil outlet is connected to the oil tank, the hydraulic motor is driven and connected to a generator, an electrical interface of the generator is connected to a motor driver, and a power source is connected to the motor driver.

As an improvement of the present invention, the power source is a battery.

As an improvement of the present invention, the second oil outlet connected with the hydraulic motor is also connected with a second check valve, and the oil inlet of the second check valve is connected with the oil outlet connected with the hydraulic motor. The first oil outlet is in communication, and the oil outlet of the second one-way valve is in communication with the oil tank.

As an improvement of the present invention, a second relief valve is also connected to the first oil outlet connected with the hydraulic motor, and the oil outlet of the second relief valve is communicated with the oil tank.

As an improvement of the present invention, the first reversing valve is a three-position, four-way reversing valve, and the second reversing valve is a two-position, two-way reversing valve.

As an improvement of the present invention, the second relief valve is a pilot-operated relief valve or a direct-acting relief valve.

As an improvement of the present invention, it further includes a controller connected in communication with the motor driver, and a first sensor for detecting the oil pressure of the oil outlet of the first valve and a first sensor for detecting the oil pressure of the oil outlet of the first valve are also connected in communication with the controller. A second sensor for detecting the oil pressure of the oil inlet of the first relief valve.

A hydraulic motor-based overflow loss recovery control method, using the above-mentioned hydraulic motor overflow loss recovery system, collecting the oil pressure of the oil inlet of the first overflow valve to obtain the inlet pressure, and collecting the first valve The oil pressure at the oil outlet obtains the outlet pressure, and takes the difference between the inlet pressure and the outlet pressure as the target value, and takes the outlet pressure as the feedback amount to perform the rotation of the hydraulic motor and/or the generator. Control to ensure that the difference between the inlet pressure and the outlet pressure is maintained within a predetermined range.

Adopting the above-mentioned technical scheme, the present invention has the following beneficial effects:

1. Through the organic combination of reversing valve, overflow valve, check valve, hydraulic motor and generator, etc., the energy recovery of overflow loss at the overflow valve port is realized. The hydraulic energy lost at the outlet is converted into electrical energy to achieve energy recovery. Since the generator can be actively controlled, the pressure difference loss at the valve port can be solved to achieve high-efficiency energy recovery.

2. By adopting the valve port differential pressure control method based on variable speed, the system can effectively solve the pressure differential loss of the overflow valve port in the overflow valve with dynamic changes of target pressure and overflow flow, and realize efficient energy recovery. Improve the pressure control accuracy of the relief valve and the stability of the system flow.

Description of drawings

1 is a schematic structural diagram of an overflow loss recovery system based on a hydraulic motor of the present invention;

FIG. 2 is a flow chart of a control strategy of the control method of the present invention.

The corresponding symbols in the figure are as follows:

1- fuel tank; 2- main pump;

3- The first one-way valve; 4- The first reversing valve;

5-The first relief valve; 6-Hydraulic cylinder;

7-drive motor; 8-second reversing valve;

9-hydraulic motor; 10-second one-way valve;

11-Second relief valve; 12-Generator;

13-motor driver; 14-power supply;

15 - Controller.

Detailed ways

The invention will be further described below in conjunction with specific embodiments:

As shown in FIG. 1 , this embodiment provides an overflow loss recovery system based on a hydraulic motor, which includes an oil tank 1 , a main pump 2 connected with the oil inlet and the oil tank, and a main pump 2 connected with the oil inlet and the oil outlet of the main pump 2 . The first one-way valve 3 , the first reversing valve 4 and the first relief valve 5 whose oil inlet is connected to the oil outlet of the first one-way valve 3 respectively, and the hydraulic cylinder 6 which is connected with the first reversing valve 4 . Among them, the main pump 2 can be a quantitative pump or a variable displacement pump, which can be selected according to actual needs; the main pump 2 is driven by the driving motor 7. Specifically, the input shaft of the main pump 2 and the output shaft of the driving motor 7 are connected through a coupling. shaft connection. In addition, each valve mentioned in this embodiment is a solenoid valve.

The first reversing valve 4 is a three-position four-way reversing valve, which has a first oil discharge port (ie, the reversing valve T port), and two first oil outlets (ie, the reversing valve A port and B port) and an oil inlet (ie, the reversing valve P port) that communicates with the oil outlet of the first check valve 3, the first oil discharge port is communicated with the oil tank 1, and one of the first oil outlets (in this embodiment) Port A of the reversing valve) is communicated with the rod chamber of the hydraulic cylinder 6, and another first oil outlet (port B of the reversing valve in this embodiment) is communicated with the rodless chamber of the hydraulic cylinder 6 for controlling The telescopic action of the hydraulic cylinder 6, specifically, when the oil flows into the rodless cavity, the oil in the rod cavity returns to the oil tank 1 through the reversing valve B port, and the hydraulic cylinder 6 performs the piston rod extension action, otherwise the hydraulic cylinder 6. Perform the retraction action of the piston rod. This type of hydraulic cylinder with a rodless cavity and a rod cavity 6 is a conventional hydraulic cylinder, which is widely used in various hydraulic drive equipment such as excavators. It can be purchased directly from the market. The key points of this embodiment will not be described in detail here.

The first relief valve 5 is a pilot-operated relief valve, and has a first valve oil outlet, a pilot oil outlet communicated with the oil tank 1, and an oil inlet communicated with the oil outlet of the first check valve 3 (ie. Relief valve P port), a second reversing valve 8 is connected to the oil outlet of the first valve. Because the first oil outlet is connected to the oil tank 1, it can play a pressure relief effect, effectively avoiding the oil pressure influence of the oil outlet of the first valve. Oil pressure at P port of relief valve.

The second reversing valve 8 is a two-position, two-way reversing valve, which has two second oil outlets (ie, the reversing valve A port and B port) and a second oil inlet that communicates with the oil outlet of the first valve (reversing valve port P), one of the second oil outlets (reversing valve A port in this embodiment) is connected to the hydraulic motor 9, and the other second oil outlet (reversing valve port in this embodiment) The valve B port) is connected to the oil tank 1. Preferably, in order to prevent the hydraulic motor 9 from being sucked in, a second one-way valve is also connected to the second oil outlet (ie, the reversing valve A port) connected to the hydraulic motor 9. 10. The oil inlet of the second check valve 10 is communicated with the first oil outlet connected with the hydraulic motor, and the oil outlet of the second check valve 10 is communicated with the oil tank 1, so that the second check valve can pass the second check valve. 10. Carry out oil replenishment to avoid the phenomenon of cavitation in the hydraulic motor 9; in addition, in order to prevent the sudden change of the pressure at the inlet of the hydraulic motor 9 when the system starts or stops and affects the normal operation of the first relief valve 5, in this embodiment, A second relief valve 11 is also connected to the first oil outlet connected with the hydraulic motor 9 . The second relief valve 11 can be a pilot-operated relief valve or a direct-acting relief valve, and its oil outlet is communicated with the oil tank 1 , which is used to relieve pressure at the moment when the system is started or stopped.

The oil outlet of the hydraulic motor 9 is communicated with the oil tank 1, and the hydraulic motor 9 is connected to the generator 12 in a driving manner. Specifically, the input shaft of the generator 12 and the output shaft of the hydraulic motor 9 are coaxially connected through a coupling. A motor driver 13 is connected to the electrical interface of the generator 12, and a power source 14 is connected to the motor driver 13, and the power source is preferably a battery. In addition, the system provided in this embodiment further includes a controller 15 that is communicatively connected to the motor driver 13, and the controller 15 is also communicatively connected to a first sensor for detecting the oil pressure of the oil outlet of the first valve and a first sensor for detecting the oil pressure of the first valve. The second sensor for the oil pressure of the oil inlet of the first relief valve 5. It should be noted that the controller 15 is a conventional controller, which can be directly purchased from the market and obtained by setting according to actual functional requirements. The specific communication connection between the controller and the motor driver 13, the first sensor and the second sensor The structure is also a conventional structure, such as wire connection or Bluetooth wireless connection, which is not the focus of this embodiment, and will not be described in detail here.

As shown in FIG. 2 , this embodiment also provides a hydraulic motor-based overflow loss recovery control method. The method is implemented by the overflow loss recovery system of the hydraulic motor. Specifically, when the above system is used, the first The inlet pressure is obtained from the oil pressure at the oil inlet of a relief valve 5, and the outlet pressure is obtained by collecting the oil pressure at the oil outlet of the first valve. Then, the difference between the inlet pressure and the outlet pressure is used as the target value, and the outlet pressure is used as the feedback The speed of the hydraulic motor 9 and/or the generator 12 is controlled to ensure that the difference between the inlet pressure and the outlet pressure is maintained within a preset range. The preset range is usually the target value, and its specific value needs to be based on According to the actual situation, in the system where the target pressure of the relief valve will change dynamically, the pressure difference of the valve port can be set according to the minimum value to effectively solve the problem of pressure difference loss of the relief valve.

When in use, when the system works in the traditional working mode, the second reversing valve 8 works in the lower position (the upper and lower positions of the second reversing valve 8 refer to FIG. Flow back to the oil tank 1; when the system works in the energy recovery mode, the second reversing valve 8 works in the upper position, and the hydraulic oil passing through the oil outlet of the first valve of the first relief valve 5 enters the hydraulic motor 9, in order to prevent hydraulic pressure When the motor 9 is emptied, oil is replenished through the second one-way valve 10; the highest pressure at the inlet of the hydraulic motor 9 is controlled by the second relief valve 11 to prevent sudden changes in the pressure at the inlet of the hydraulic motor 9 when the system starts or stops. The normal operation of the first relief valve 5 is affected.

The system and method provided in this embodiment are applicable to oil circuits including an inlet throttle speed control loop, an outlet throttle speed control loop, an inlet and outlet linkage throttle speed control loop, and a bypass throttle speed control loop. Regulating overflow loss or safety overflow loss for energy recovery. The system and method provided in this embodiment are mainly used for the energy recovery of the overflow valve overflow loss of mobile machinery such as excavators, forklifts, and loaders, and various types of stationary machinery. Under various working conditions, the valve port pressure difference value is controlled. In order to ensure the minimum value of the normal operation of the overflow valve, the problem of pressure differential loss of the overflow valve is solved, the recovery pressure range of the overflow loss is expanded, and the utilization rate of energy recovery is improved.

A hydraulic motor-based overflow loss recovery system and its control method proposed in this embodiment convert most of the pressure difference originally consumed on the overflow valve port into electrical energy through the hydraulic motor and the generator and recover it; The valve port differential pressure control method of the rotational speed controls the inlet and outlet pressure differential value of the relief valve to be the minimum value to ensure that the relief valve can work normally, and solves the problem of pressure differential loss on the relief valve itself. When the target pressure and overflow flow of the relief valve change dynamically, the pressure of the system can respond quickly, so that the system has a good recovery efficiency. This energy recovery method increases the outlet pressure of the relief valve, which improves the stability of the hydraulic system and the pressure control characteristics of the relief valve to a certain extent.

The present invention has been described in detail above in conjunction with the accompanying drawings, but the embodiments of the present invention are not limited to the above-mentioned embodiments. Those skilled in the art can make various modifications to the present invention according to the prior art, which all belong to the protection scope of the present invention. .

Claims (8)

1. An overflow loss recovery system based on a hydraulic motor is characterized by comprising an oil tank, a main pump with an oil inlet connected with the oil tank, a first one-way valve with an oil inlet connected with an oil outlet of the main pump, a first reversing valve and a first overflow valve with oil inlets respectively connected with oil outlets of the first one-way valve, and a hydraulic cylinder connected with the first reversing valve, wherein the first reversing valve is provided with a first oil discharge port and two first oil outlets, one of the first oil outlets is communicated with a rod cavity of the hydraulic cylinder, the other first oil outlet is communicated with a rodless cavity of the hydraulic cylinder, the first oil discharge port is communicated with the oil tank, the first overflow valve is provided with a first valve oil outlet and a pilot oil outlet communicated with the oil tank, the first valve oil outlet is connected with a second reversing valve, the second reversing valve is provided with two second oil outlets and a second oil inlet communicated with the first valve oil outlet, one of the second oil outlets is connected with a hydraulic motor, the other second oil outlet is connected with the oil tank, the hydraulic motor is connected with a generator in a transmission mode, an electric interface of the generator is connected with a motor driver, and a power supply is connected to the motor driver.

2. A hydraulic motor based spill loss recovery system as claimed in claim 1, wherein said power source is a battery.

3. The hydraulic motor based overflow loss recovery system of claim 1, wherein a second one-way valve is further connected to the second oil outlet to which the hydraulic motor is connected, an oil inlet of the second one-way valve is communicated with the first oil outlet to which the hydraulic motor is connected, and an oil outlet of the second one-way valve is communicated with the oil tank.

4. The hydraulic motor based spill loss recovery system of claim 1, wherein a second spill valve is further connected to the first outlet port to which the hydraulic motor is connected, an outlet port of the second spill valve being in communication with the oil tank.

5. The hydraulic motor based spill loss recovery system of claim 1, wherein the first directional valve is a three-position, four-way directional valve and the second directional valve is a two-position, two-way directional valve.

6. A hydraulic motor based spill loss recovery system as claimed in claim 1, wherein said second spill valve is a pilot-operated spill valve or a direct-operated spill valve.

7. The hydraulic motor based spill loss recovery system of claim 1, further comprising a controller communicatively coupled to the motor drive, the controller further communicatively coupled to a first sensor for detecting oil pressure at the first valve outlet and a second sensor for detecting oil pressure at the first spill valve inlet.

8. A hydraulic motor-based overflow loss recovery control method is characterized in that the overflow loss recovery system of the hydraulic motor is adopted, the oil pressure of an oil inlet of a first overflow valve is collected to obtain inlet pressure, the oil pressure of an oil outlet of a first valve is collected to obtain outlet pressure, the difference value of the inlet pressure and the outlet pressure is used as a target value, and the outlet pressure is used as a feedback quantity to control the rotation speed of the hydraulic motor and/or the generator so as to ensure that the difference value of the inlet pressure and the outlet pressure is maintained within a preset range.

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