Emergency hydraulic system with open center and closed center load sensitive systems

Abstract

According to the emergency hydraulic system with the open center load-sensitive system and the closed center load-sensitive system, a priority valve and an emergency metering pump are arranged between the open center PSL load-sensitive system and the closed center PSV load-sensitive system, energy is saved, and efficiency is high; the priority valve can constantly adjust the outlet pressure of the emergency metering pump to adapt to the load, the condition of pump outlet high-pressure overflow when the metering pump is connected into a closed center load sensitive system is avoided, meanwhile, the pump outlet pressure always adapts to the highest load pressure, a high energy-saving effect is achieved, the heating value of the system during working is reduced, and the service life of the system is prolonged. And the problems that a manual or electric control switching valve needs to be configured during switching work of a closed center system and an open center system in an existing direct merging method, operation is tedious, and errors are prone to occurring are solved.

Description

Technical Field

[0001] The utility model belongs to the technical fields of engineering machinery, special vehicles, industrial equipment, etc., and particularly relates to an emergency hydraulic system with an open-center and closed-center load-sensitive system. Background Art

[0002] Modern machinery has put forward higher and higher requirements on the reliability, simplicity of operation, and transmission efficiency of hydraulic systems. In order to meet the requirements of energy saving and high transmission efficiency, many equipments use open center (fixed displacement pump) load sensing system or closed center (variable displacement pump) load sensing system. The former can achieve the real-time adaptation of pump outlet pressure and load size under different working conditions and loads, while the latter can achieve the real-time adaptation of pump outlet pressure and flow rate and load under different working conditions and loads. Therefore, these two load sensing systems have been widely used in equipments due to their different degrees of energy saving effects and costs.

[0003] In order to meet the reliability requirements of the main engine, configuring a low-power emergency hydraulic power source is a common method. When the main engine of the equipment fails, the low-power emergency power source can be used to enable the main engine to complete various functions in the emergency state and quickly escape from the predicament.

[0004] The existing scheme for configuring an emergency hydraulic power source generally adopts a small-power DC motor plus a metering pump, and directly connects it to the main system of the equipment after connecting a relief valve in parallel at the pump outlet. At this time, when the main system is an open-center load-sensitive system, the outlet pressure of the emergency metering pump can adapt to the load, the hydraulic system has a relatively high transmission efficiency, and the energy storage device (such as a battery) equipped with the emergency metering pump group of the equipment can work for a long time; when the main system of the equipment is a closed-center (variable pump) load-sensitive system, the existing direct incorporation scheme has a very low system efficiency. At this time, no matter how the load changes, the outlet of the emergency metering pump always maintains the set pressure of the high-pressure relief valve, especially when the throttle port of the main valve is very small or closed, a large amount of high-pressure oil returns to the oil tank after passing through the relief valve, causing a lot of heating in the system. At the same time, the emergency metering pump continues to be at high pressure, resulting in a shortened working time of the backup energy storage device (such as a battery).

[0005] When the main system has both an open center load-sensitive system and a closed center load-sensitive system, the existing direct incorporation solution will render the closed center system inoperable (the emergency metering pump oil returns directly to the tank from the open center valve first joint low pressure, and pressure cannot be built up. At this time, a switching valve group needs to be configured to isolate the open center system and the closed center system to avoid direct parallel connection. The operation is relatively cumbersome and not energy-efficient).

[0006] Therefore, it is particularly important to design an energy-saving and efficient emergency hydraulic system that can adapt to both open-center and closed-center load-sensitive systems. Summary of the invention

[0007] The purpose of the utility model is to provide a solution for a quantitative pump emergency power source which is applicable to both an open center quantitative pump load sensing system and a closed center variable pump load sensing system in view of the above-mentioned deficiencies in the prior art.

[0008] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0009] An emergency hydraulic system with an open center and a closed center load sensing system, comprising an open center PSL load sensing system, a closed center PSV load sensing system, and a priority valve and an emergency quantitative pump arranged therebetween;

[0010] The open center PSL load sensing system comprises an open center PSL load sensing valve group and a first one-way valve connected to the inlet thereof, wherein the oil inlet of the first one-way valve is connected to the metering pump, and the fourth oil port of the priority valve is connected to the oil path between the first one-way valve and the open center PSL load sensing valve group;

[0011] The closed center PSV load sensing system comprises a closed center PSV load sensing valve group and a second one-way valve connected to a first inlet thereof, and an oil inlet of the second one-way valve is connected to a fourth oil port of the load sensing variable pump;

[0012] A third one-way valve is also provided on the oil circuit between the priority valve and the emergency metering pump, and the oil outlet of the third one-way valve is connected to the first oil port of the priority valve, and a relief valve is also connected in parallel between the emergency metering pump and the oil inlet of the third one-way valve;

[0013] The third oil port of the priority valve is connected to the oil circuit between the second one-way valve and the closed center PSL load-sensitive valve group. The second oil port of the priority valve is the load signal feedback port and is connected to the third oil port of the load-sensitive variable pump and the oil circuit of the second inlet of the closed center PSV load-sensitive valve group.

[0014] The second oil port of the priority valve receives the Ls pressure signal, and adjusts the output flow ratio of the third oil port and the fourth oil port according to the Ls pressure signal;

[0015] When the second oil port of the priority valve is fed back with pressure, the flow of the emergency metering pump is first supplied to the third oil port of the priority valve, and reaches the first inlet of the closed center PSV load sensing valve group. The remaining flow reaches the first oil port of the open center PSL load sensing valve group through the fourth oil port of the priority valve, and finally returns to the hydraulic oil tank through its second oil port;

[0016] When there is no load pressure signal at the second oil port of the priority valve, the flow of the emergency metering pump is fully supplied to the fourth oil port of the priority valve and returns to the hydraulic oil tank through the second oil port of the open center PSL load sensitive valve group.

[0017] When there is pressure feedback from the second oil port of the priority valve, the outlet pressure of the emergency metering pump is adapted to the maximum load pressure of the closed center PSV load-sensitive valve group, and is always greater than the maximum load pressure by a fixed value, and the fixed value is set equal to the spring pressure value of the priority valve.

[0018] The spring pressure value of the priority valve is 1.2 MPa, so the fixed value is also set to 1.2 MPa.

[0019] When there is no feedback signal from the second oil port of the priority valve, the outlet pressure of the emergency metering pump is adapted to the maximum load pressure of the open center PSL load-sensitive valve group, and is always higher than the maximum load pressure by a fixed value, which is set equal to the spring set pressure of the three-way constant pressure differential valve inside the open center load-sensitive valve group.

[0020] The spring setting pressure of the three-way constant pressure differential valve inside the open center load-sensitive valve group is 1.4 MPa, and the fixed value is also set to 1.4 MPa.

[0021] The first oil port and the third oil port of the load-sensing variable displacement pump both lead to the hydraulic oil tank.

[0022] The inlets of the metering pump and the emergency metering pump are both connected to the hydraulic oil tank.

[0023] The inlet of the overflow valve is communicated with the hydraulic oil tank.

[0024] The beneficial effects of the utility model are:

[0025] (1) The emergency hydraulic system with open-center and closed-center load sensing systems saves energy and has high efficiency by arranging a priority valve and an emergency quantitative pump between the open-center PSL load sensing system and the closed-center PSV load sensing system;

[0026] The priority valve can always adjust the outlet pressure of the emergency metering pump to adapt to the load, avoiding the high-pressure overflow of the pump outlet when the metering pump is connected to the closed-center load-sensitive system. At the same time, the pump outlet pressure is always adapted to the maximum load pressure, which has a high energy-saving effect and reduces the heat generated by the system during operation.

[0027] (2) Easy to operate;

[0028] Because the main system has both a closed center load-sensitive system and an open center load-sensitive system, the utility model realizes the automatic switching and simultaneous operation of the closed center load-sensitive system and the open center load-sensitive system by configuring a priority valve. When the closed center PSV load-sensitive valve group is actuated, the load feedback signal Ls enters the priority valve spring chamber. At this time, the emergency metering pump oil enters the PSV valve group first, and the excess oil enters the PSL valve group. When the emergency metering pump flow is sufficient, it can ensure that the PSV valve group and the PSL valve group work simultaneously. When the closed center PSV load-sensitive valve group does not actuate, the emergency metering pump oil all enters the PSL valve group. The above process is all completed automatically, does not require human intervention, and is easy to operate. It solves the problem that the existing direct incorporation method needs to configure a manual or electrically controlled switching valve when switching between the closed center system and the open center system, which is cumbersome and error-prone. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a hydraulic principle diagram of the utility model. DETAILED DESCRIPTION

[0030] The following is a description of the implementation of the present invention by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0031] The utility model provides an emergency hydraulic system with an open center and a closed center load sensing system, such as Figure 1 shown.

[0032] An emergency hydraulic system with an open center and a closed center load sensing system, comprising an open center PSL load sensing system, a closed center PSV load sensing system, and a priority valve 5 and an emergency metering pump 7 arranged therebetween; the open center PSL load sensing system comprises an open center PSL load sensing valve group 1 and a first one-way valve 3 connected to its inlet, and the oil inlet of the first one-way valve 3 Connected to the metering pump 4, and the fourth oil port of the priority valve 5 Connected to the oil circuit between the first non-return valve 3 and the open-center PSL load-sensing valve group 1.

[0033] The closed center PSV load sensing system comprises a closed center PSV load sensing valve group 2 and a first inlet The second one-way valve 9 is connected, and the oil inlet of the second one-way valve 9 The fourth oil port of the load sensing variable pump 10 connect.

[0034] A third one-way valve 6 is also provided in the oil circuit between the priority valve 5 and the emergency metering pump 7, and the oil outlet of the third one-way valve 6 is First port with priority valve 5 The emergency metering pump 7 is connected to the oil inlet of the third one-way valve 6. A relief valve 8 is also connected in parallel, and the lower inlet of the relief valve 8 Connected to the hydraulic oil tank 11.

[0035] The third oil port of priority valve 5 Connected to the oil line between the second check valve 9 and the closed center PSV load sensing valve group 2, the second oil port of the priority valve 5 The third oil port of the load signal feedback port connected to the load sensing variable pump 10 and closed center PSV load sensing valve group 2 second inlet On the oil road.

[0036] The second oil port of the priority valve 5 receives the Ls pressure signal and adjusts the third oil port according to the Ls pressure signal. And the fourth oil port The output flow ratio.

[0037] When the second oil port of priority valve 5 That is, when there is pressure at the load signal feedback port, the flow of the emergency metering pump 7 is first guaranteed to be supplied to the third oil port of the priority valve. , reaching the first inlet of the closed center PSV load sensing valve group 2 The remaining flow passes through the fourth oil port of priority valve 5 To the first oil port of the open center PSL load sensing valve group 1 , and finally through its second oil port Back to the hydraulic tank.

[0038] When the second oil port of priority valve 5 When there is no load pressure signal, the flow of the emergency metering pump 7 is fully supplied to the fourth oil port of the priority valve 5 , by opening the second oil port of the central PSL load sensing valve group 1 Return to the hydraulic oil tank 11.

[0039] The second oil port of the hydraulic priority valve 5 When there is an Ls feedback signal, the outlet pressure of the emergency metering pump 7 is adapted to the maximum load pressure of the closed center PSV load-sensitive valve group 2, and is always greater than the maximum load pressure by a fixed value, and the fixed value is set identically to the spring pressure value of the priority valve; in this embodiment, the spring pressure value of the priority valve is 1.2 MPa, and the fixed value is also set to 1.2 MPa.

[0040] On the second port of priority valve 5 When there is no Ls feedback signal, the outlet pressure of the emergency metering pump 7 is adapted to the maximum load pressure of the open center load-sensitive valve group 1, and is always higher than the maximum load pressure by a fixed value, which is set equal to the spring setting pressure of the three-way constant pressure differential valve inside the open center load-sensitive valve group; in this embodiment, the spring setting pressure of the three-way constant pressure differential valve inside the open center load-sensitive valve group is 1.4 MPa, and the fixed value is also set to 1.4 MPa.

[0041] In addition, when the emergency metering pump 7 is working, there is no need to operate the manual valve group. The system can automatically adjust and distribute the flow of the emergency metering pump 7 entering the closed center PSV load sensitive valve group 2 and the open center PSL load sensitive valve group 1 according to the emergency operation (open center PSL load sensitive valve group 1 is actuated or closed center PSV load sensitive valve group 2 is actuated).

[0042] The first oil port of the load sensing variable displacement pump And the third oil port Both lead to the hydraulic oil tank 11 ; the inlets of the metering pump 4 and the emergency metering pump 7 are connected to the hydraulic oil tank 11 .

[0043] The working principle of the utility model is as follows:

[0044] When the closed center PSV load sensing valve group 2 is activated, the load feedback signal Ls enters the spring chamber of the priority valve 5, that is, the second oil port At this time, the oil of the emergency metering pump 7 first enters the first inlet of the closed center PSV load sensing valve group 2 The excess oil flows into the first oil port of the open center PSL load sensing valve group 1 When the flow of the emergency metering pump 7 is sufficient, it can ensure that the closed center PSV load-sensitive valve group 2 and the open center PSL load-sensitive valve group 1 work at the same time; among them, the maximum load pressure of the open center PSL load-sensitive valve group 1 needs to be lower than the maximum load pressure of the closed center PSV load-sensitive valve group 2. At this time, the outlet pressure of the emergency metering pump 7 is adapted to the maximum load pressure of the closed center PSV load-sensitive valve group 2, and is always higher by a fixed value (the spring setting pressure value of the priority valve 5). When the closed center PSV load-sensitive valve group 2 does not act, no Ls signal enters the spring chamber of the priority valve 5, i.e., the second oil port. At this time, the oil of the emergency metering pump 7 all enters the first oil port of the open center PSL load sensing valve group 1 At this time, the outlet pressure of the emergency metering pump 7 is adapted to the maximum load pressure of the open center PSL load sensitive valve group 1.

[0045] The utility model realizes the automatic switching and simultaneous operation of the closed center load sensitive system and the open center load sensitive system by configuring the priority valve. When the closed center PSV load sensitive valve group is actuated, the load feedback signal Ls enters the priority valve spring chamber. At this time, the emergency metering pump oil enters the PSV valve group first, and the excess oil enters the PSL valve group. When the emergency metering pump flow is sufficient, it can ensure that the PSV valve group and the PSL valve group work simultaneously; when the closed center PSV load sensitive valve group does not act, the emergency metering pump oil all enters the PSL valve group; the above process is all completed automatically, does not require human intervention, and is easy to operate.

[0046] If the words "first", "second" and so on are used in this patent to limit components, those skilled in the art should know that the use of "first" and "second" is only for the convenience of describing the utility model and simplifying the description, and the above words have no special meaning.

[0047] The above shows and describes the basic principle, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principle of the utility model. The utility model may have various changes and improvements without departing from the spirit and scope of the utility model. These changes and improvements fall within the scope of the utility model to be protected. The scope of protection claimed by the utility model is defined by the attached claims and their equivalents.

[0048] In the description of the present invention, it is necessary to understand that the terms "front", "rear", "left", "right", "center", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the protection content of the present invention.

Claims

1. An emergency hydraulic system with open center and closed center load sensing system, characterized in that: It includes an open center PSL load sensing system, a closed center PSV load sensing system, and a priority valve and an emergency metering pump arranged between the two; The open center PSL load sensing system comprises an open center PSL load sensing valve group and a first one-way valve connected to the inlet thereof, wherein the oil inlet of the first one-way valve is connected to the metering pump, and the fourth oil port of the priority valve is connected to the oil path between the first one-way valve and the open center PSL load sensing valve group; The closed center PSV load sensing system comprises a closed center PSV load sensing valve group and a second one-way valve connected to a first inlet thereof, and an oil inlet of the second one-way valve is connected to a fourth oil port of the load sensing variable pump; A third one-way valve is also provided on the oil circuit between the priority valve and the emergency metering pump, and the oil outlet of the third one-way valve is connected to the first oil port of the priority valve, and a relief valve is also connected in parallel between the emergency metering pump and the oil inlet of the third one-way valve; The third oil port of the priority valve is connected to the oil circuit between the second one-way valve and the closed center PSL load-sensitive valve group. The second oil port of the priority valve is the load signal feedback port and is connected to the third oil port of the load-sensitive variable pump and the oil circuit of the second inlet of the closed center PSV load-sensitive valve group.

2. An emergency hydraulic system with open center and closed center load sensing system according to claim 1, characterized in that: The second oil port of the priority valve receives the Ls pressure signal, and adjusts the output flow ratio of the third oil port and the fourth oil port according to the Ls pressure signal; When the second oil port of the priority valve is fed back with pressure, the flow of the emergency metering pump is first supplied to the third oil port of the priority valve, and reaches the first inlet of the closed center PSV load sensing valve group. The remaining flow reaches the first oil port of the open center PSL load sensing valve group through the fourth oil port of the priority valve, and finally returns to the hydraulic oil tank through its second oil port; When there is no load pressure signal at the second oil port of the priority valve, the flow of the emergency metering pump is fully supplied to the fourth oil port of the priority valve and returns to the hydraulic oil tank through the second oil port of the open center PSL load sensitive valve group.

3. An emergency hydraulic system with open center and closed center load sensing system according to claim 2, characterized in that: When there is pressure feedback from the second oil port of the priority valve, the outlet pressure of the emergency metering pump is adapted to the maximum load pressure of the closed center PSV load-sensitive valve group, and is always greater than the maximum load pressure by a fixed value, and the fixed value is set equal to the spring pressure value of the priority valve.

4. An emergency hydraulic system with open center and closed center load sensing system according to claim 3, characterized in that: The spring pressure value of the priority valve is 1.2 MPa, so the fixed value is also set to 1.2 MPa.

5. An emergency hydraulic system with open center and closed center load sensing system according to claim 2, characterized in that: When there is no feedback signal from the second oil port of the priority valve, the outlet pressure of the emergency metering pump is adapted to the maximum load pressure of the open center PSL load-sensitive valve group, and is always higher than the maximum load pressure by a fixed value, which is set equal to the spring set pressure of the three-way constant pressure differential valve inside the open center load-sensitive valve group.

6. An emergency hydraulic system with open center and closed center load sensing system according to claim 5, characterized in that: The spring setting pressure of the three-way constant pressure differential valve inside the open center load-sensitive valve group is 1.4 MPa, and the fixed value is also set to 1.4 MPa.

7. An emergency hydraulic system with open center and closed center load sensing system according to any one of claims 1 to 6, characterized in that: The first oil port and the third oil port of the load-sensing variable displacement pump both lead to the hydraulic oil tank.

8. An emergency hydraulic system with open center and closed center load sensing system according to any one of claims 1 to 6, characterized in that: The inlets of the metering pump and the emergency metering pump are both connected to the hydraulic oil tank.

9. An emergency hydraulic system with open center and closed center load sensing system according to any one of claims 1 to 6, characterized in that: The inlet of the overflow valve is communicated with the hydraulic oil tank.

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