Hydraulic cylinder semi-closed hydraulic system driven by motor

Abstract

The utility model provides a semi-closed hydraulic system of a hydraulic cylinder driven by a motor, which can supplement a small amount of hydraulic oil, meet the difference between the hydraulic oil quantity of a rod cavity and the hydraulic oil quantity of a rodless cavity of the oil cylinder, timely supplement hydraulic oil to a liquid inlet / outlet with lower pressure of a hydraulic pump / motor, prevent the hydraulic pump / motor from generating an air suction phenomenon at the moment of starting, and improve the working efficiency of the hydraulic cylinder. Comprising an oil cylinder; a rod cavity of the oil cylinder is communicated with a first liquid inlet / outlet of the hydraulic pump / motor through a first oil way, and a rodless cavity of the oil cylinder is communicated with a second liquid inlet / outlet of the hydraulic pump / motor through a second oil way. The motor is directly or indirectly connected with the hydraulic pump / motor; two oil inlets of the oil drainage direction control valve are communicated with the first oil way and the second oil way respectively, and an oil outlet of the oil drainage direction control valve is communicated to the oil tank through the oil drainage pressure stabilizing valve. The oil drainage direction control valve enables the oil path with lower pressure in the first oil path and the second oil path to be communicated with the oil drainage pressure stabilizing valve; the liquid supplementing oil way is communicated with the first oil way and the second oil way through liquid supplementing one-way valves.

Description

A semi-closed hydraulic system with an electric motor-driven hydraulic cylinder Technical Field

[0001] This utility model relates to a semi-closed hydraulic system with a hydraulic cylinder, specifically, a semi-closed hydraulic system with a hydraulic cylinder driven by an electric motor. Background Technology

[0002] In the field of construction machinery, open hydraulic structures are generally used. Due to the use of a single engine, the hydraulic system design is very complex. The high-speed flow of hydraulic oil in the oil circuit results in a complex system structure and low efficiency.

[0003] Closed-loop hydraulic transmission can largely avoid ineffective hydraulic oil flow and has high transmission efficiency. However, closed-loop hydraulic systems are mainly suitable for scenarios where the loads in two directions are relatively balanced and the oil intake and discharge volumes of the actuators are equal during forward and reverse movements, such as the swing and travel of excavators. For cylinder-type actuators, due to unbalanced loads and large differences in oil intake and discharge volumes, it is difficult to implement closed-loop hydraulic systems.

[0004] The technology described in the document with application publication number CN119900740A, although capable of realizing a closed hydraulic system, has a balance valve that simultaneously controls the on / off state of the replenishment circuit and the pump circuit. If the pressure direction is uncertain when the pump starts, the pump oil circuit cannot replenish fluid in time, causing the pump to "suck air" at the moment of startup, which affects the service life of the pump. Summary of the Invention

[0005] The purpose of this invention is to provide a semi-closed hydraulic system for a motor-driven hydraulic cylinder. During the cylinder's operation, a small amount of hydraulic oil can be added to meet the difference in hydraulic oil volume between the rod-side and rodless sides of the cylinder. At the same time, it can promptly replenish hydraulic oil to the lower-pressure inlet / outlet ports of the hydraulic pump / motor, preventing the hydraulic pump / motor from "suctioning air" at startup and ensuring the stable performance and service life of the hydraulic pump / motor.

[0006] A semi-closed hydraulic system driven by an electric motor includes a double-acting piston cylinder with a rod chamber and a rodless chamber. The rod chamber of the cylinder is connected to the first inlet / outlet of a hydraulic pump / motor via a first oil passage, and the rodless chamber is connected to the second inlet / outlet of the hydraulic pump / motor via a second oil passage. The electric motor is directly or indirectly connected to the hydraulic pump / motor. The two inlets of a drain directional control valve are respectively connected to the first oil passage and the second oil passage, and the outlet of the drain directional control valve is connected to an oil tank via a drain pressure stabilizing valve. The drain directional control valve connects the oil passage with the lower pressure between the first and second oil passages to the drain pressure stabilizing valve. A replenishment oil passage for replenishing oil to the first or second oil passage is connected to the first and second oil passages via a replenishment check valve.

[0007] The aforementioned motor-driven semi-closed hydraulic system includes a replenishing pump that rotates under the drive of a replenishing motor. The outlet of the replenishing pump is connected to the first and second oil circuits via replenishing check valves.

[0008] In the aforementioned semi-closed hydraulic system with a motor-driven hydraulic cylinder, the outlet of the replenishing pump is connected to the oil tank via an overflow valve.

[0009] In the aforementioned semi-closed hydraulic system with a motor-driven hydraulic cylinder, the first and second oil circuits are connected to the oil tank via relief valves.

[0010] The aforementioned motor-driven semi-closed hydraulic system uses a hydraulic pump / motor with either a constant or variable displacement capacity.

[0011] In the aforementioned semi-closed hydraulic system with a motor-driven hydraulic cylinder, when the hydraulic pump / motor is used as a pump, it pumps hydraulic oil to the cylinder under the drive of the motor. When used as a motor, the cylinder drives the hydraulic pump / motor through the hydraulic oil, thereby driving the motor to generate electricity and realizing the recovery of kinetic and potential energy.

[0012] The beneficial effects of this utility model are:

[0013] In this invention, the drain direction control valve connects the oil circuit with lower pressure in the first and second oil circuits to the drain pressure stabilizing valve.

[0014] When the hydraulic pump / motor pumps oil into the rodless chamber of the cylinder, if the oil pressure in the rodless chamber (i.e., the oil pressure in the second oil circuit) is higher than the oil pressure in the rod chamber (i.e., the oil pressure in the first oil circuit), the oil circuit in the rod chamber (i.e., the first oil circuit) replenishes oil through the replenishing check valve one. If the oil pressure in the rodless chamber (i.e., the oil pressure in the second oil circuit) is lower than the oil pressure in the rod chamber (i.e., the oil pressure in the first oil circuit), the oil circuit in the rodless chamber (i.e., the second oil circuit) replenishes oil through the replenishing check valve two. In other words, when the hydraulic pump / motor pumps oil into the rodless chamber of the cylinder, the oil circuit with lower pressure replenishes oil through the replenishing check valve.

[0015] When the hydraulic pump / motor pumps oil into the rod chamber of the cylinder, if the oil pressure in the rodless chamber (i.e., the oil pressure in the second oil circuit) is higher than the oil pressure in the rod chamber (i.e., the oil pressure in the first oil circuit), the excess oil in the rod chamber's oil circuit (i.e., the first oil circuit) flows back to the oil tank through the drain and pressure regulating valve. If the oil pressure in the rodless chamber (i.e., the oil pressure in the second oil circuit) is lower than the oil pressure in the rod chamber (i.e., the oil pressure in the first oil circuit), the excess oil in the rodless chamber's oil circuit (i.e., the second oil circuit) flows back to the oil tank through the drain and pressure regulating valve. In other words, when the hydraulic pump / motor pumps oil into the rod chamber of the cylinder, the excess oil in the lower-pressure oil circuit flows back to the oil tank through the drain and pressure regulating valve.

[0016] This utility model is a semi-closed hydraulic system that can replenish a small amount of hydraulic oil during the operation of the cylinder to meet the difference in hydraulic oil volume between the rod chamber and the rodless chamber of the cylinder. At the same time, it can replenish hydraulic oil in a timely manner to the low-pressure inlet / outlet ports of the hydraulic pump / motor, preventing the hydraulic pump / motor from "suctioning air" at the moment of startup, and ensuring the stable performance and service life of the hydraulic pump / motor. Attached Figure Description

[0017] Figures 1 and 2 are schematic diagrams of the semi-closed hydraulic system of the hydraulic cylinder in Examples 1 and 2, respectively. Detailed Implementation

[0018] Example 1:

[0019] Referring to Figure 1, the motor-driven semi-closed hydraulic system includes a double-acting piston cylinder 1 with a rod chamber and a rodless chamber. The rod chamber of the cylinder is connected to the first inlet / outlet of the hydraulic pump / motor via a first oil passage 2, and the rodless chamber is connected to the second inlet / outlet of the hydraulic pump / motor 4 via a second oil passage 3. The motor 5 is directly connected to the hydraulic pump / motor 4 to drive it. A drain directional control valve 6 is located between the first oil passage 2 and the second oil passage 3. This drain directional control valve is a three-position three-way directional valve, with its two inlets connected to the first and second oil passages respectively, and its outlet connected to the oil tank via a drain pressure regulating valve 7. Its two control ports are also connected to the first and second oil passages respectively. The control port adjusts the action of the drain direction control valve 6 according to the oil pressure of the first oil circuit and the second oil circuit, so that the oil circuit with lower pressure (the one with lower pressure is the oil circuit between the pressure of the first oil circuit 2 and the pressure of the second oil circuit 3) is connected to the drain pressure regulating valve.

[0020] The replenishment oil circuit 8 includes a replenishment pump 10 that rotates under the drive of a replenishment motor 9. The outlet of the replenishment pump 10 is connected to the first oil circuit 2 through a replenishment check valve 12 and to the second oil circuit 3 through a replenishment check valve 13.

[0021] The first oil circuit 2 is connected to the oil tank via overflow valve 14, and the second oil circuit 3 is connected to the oil tank via overflow valve 15.

[0022] When the motor drives the pump to pump oil into the rodless chamber of the cylinder, if the oil pressure in the rodless chamber (i.e., the oil pressure in the second oil circuit) is higher than the oil pressure in the rod chamber (i.e., the oil pressure in the first oil circuit), the drain direction control valve connects the rod chamber with the drain pressure stabilizing valve. At this time, the change in oil volume in the rodless chamber oil circuit (i.e., the second oil circuit) is greater than the change in oil volume in the rod chamber, and the oil circuit in the rod chamber (i.e., the first oil circuit) replenishes oil through the replenishment check valve.

[0023] When the motor drives the pump to pump oil into the rod chamber of the cylinder, if the oil pressure in the rod chamber is higher than that in the rodless chamber, the drain direction control valve connects the rodless chamber to the drain pressure regulating valve. At this time, the change in oil volume in the rod chamber is less than that in the rodless chamber, and the excess oil in the rodless chamber flows back to the oil tank through the drain pressure regulating valve.

[0024] When the motor drives the pump to pump oil into the rodless chamber of the cylinder, if the oil pressure in the rodless chamber is lower than that in the rod chamber, the drain direction control valve connects the rodless chamber to the drain pressure stabilizing valve. At this time, the change in oil volume in the rodless chamber is greater than that in the rod chamber. The amount of oil pumped to the rodless chamber is less than the amount of oil required by the rodless chamber. The oil in the rodless chamber is replenished through the replenishing check valve.

[0025] When the motor drives the pump to pump oil into the rod chamber of the cylinder, if the oil pressure in the rod chamber is lower than that in the rodless chamber, the drain directional control valve connects the rod chamber to the drain pressure regulating valve. At this time, the change in oil volume in the rod chamber is less than that in the rodless chamber. The volume of oil pumped to the rod chamber is greater than the volume of oil required by the rod chamber. The excess oil in the rod chamber flows back to the oil tank through the drain pressure regulating valve.

[0026] Example 2:

[0027] Referring to Example 2 shown in Figure 2, the main difference between it and Example 1 is that the overflow ends of overflow valve 14 and overflow valve 25 are connected to the replenishing oil circuit.

[0028] In summary, the technical features of this utility model are as follows:

[0029] A semi-closed hydraulic system driven by an electric motor includes at least one pump / motor and at least one cylinder. The two oil ports of the pump / motor are connected to the two oil ports of the cylinder via oil passages. A drain direction control valve is provided between the oil passages of the two oil ports of the pump / motor. The drain direction control valve is connected to an oil tank via a drain pressure stabilizing valve. A replenishment check valve is provided on each of the oil passages corresponding to the two oil ports of the pump / motor and connected to the replenishment oil passage.

[0030] The pump / motor mentioned refers to a hydraulic component that can be used as both a pump and a motor. In this structure, the hydraulic cylinder can reverse the pump / motor, thereby driving the motor to generate electricity and realizing the recovery of kinetic and potential energy.

[0031] The aforementioned drain directional control valve connects the lower-pressure end of the oil circuit at both ends of the pump / motor to the oil tank via the drain pressure regulating valve. Excess oil generated during the piston movement of the cylinder flows back to the oil tank through the drain pressure regulating valve. The drain pressure regulating valve maintains a certain pressure in the oil circuit to meet the operating requirements of the pump / motor.

[0032] The aforementioned replenishing check valve is used to allow oil from the replenishing oil circuit to enter the pump / motor's oil circuit when the oil pressure at both ends of the pump / motor is lower than the pump / motor's minimum inlet oil pressure, thereby ensuring the normal function and lifespan of the pump / motor.

[0033] The pump / motor mentioned can be either a constant displacement pump or a variable displacement pump.

[0034] An overflow valve can be installed on the oil lines at both ends of the pump / motor to protect the oil lines and related components. The overflow end of the overflow valve can be connected to the replenishing oil line (as shown by the dotted line in Figure 2) or directly connected to the oil tank (as shown in Figure 1).

[0035] The technology described in application publication number CN 119900740 A, while achieving the same function, involves a balance valve that simultaneously controls the on / off state of both the replenishment circuit and the pump circuit. If the pressure direction is uncertain during pump startup, this can lead to insufficient replenishment of the pump's oil circuit, causing a "cavitation" phenomenon at startup and affecting the pump's service life. This structure effectively solves this problem by incorporating replenishment check valves (including replenishment check valve one and replenishment check valve two) between the pump's two oil circuits and the replenishment oil circuit.

[0036] Principle description:

[0037] When the motor drives the pump to pump oil into the rodless chamber of the cylinder, if the oil pressure in the rodless chamber is higher than that in the rod chamber, the drain direction control valve connects the rod chamber to the drain pressure stabilizing valve. At this time, the change in oil volume in the rodless chamber is greater than the change in oil volume in the rod chamber, and the oil in the rod chamber is replenished with oil through the replenishment check valve.

[0038] When the motor drives the pump to pump oil into the rod chamber of the cylinder, if the oil pressure in the rod chamber is higher than that in the rodless chamber, the drain direction control valve connects the rodless chamber to the drain pressure regulating valve. At this time, the change in oil volume in the rod chamber is less than the change in oil volume in the rodless chamber, and the excess oil in the rodless chamber flows back to the oil tank through the drain pressure regulating valve.

[0039] When the motor drives the pump to pump oil into the rodless chamber of the cylinder, if the oil pressure in the rodless chamber is lower than that in the rod chamber, the drain direction control valve connects the rodless chamber to the drain pressure stabilizing valve. At this time, the change in oil volume in the rodless chamber is greater than that in the rod chamber. The amount of oil pumped to the rodless chamber is less than the amount of oil required by the rodless chamber. The oil in the rodless chamber is replenished through the replenishing check valve.

[0040] When the motor drives the pump to pump oil into the rod chamber of the cylinder, if the oil pressure in the rod chamber is lower than that in the rodless chamber, the drain directional control valve connects the rod chamber to the drain pressure regulating valve. At this time, the change in oil volume in the rod chamber is less than the change in oil volume in the rodless chamber. The volume of oil pumped to the rod chamber is greater than the volume required by the rod chamber. The excess oil in the rod chamber flows back to the oil tank through the drain pressure regulating valve.

[0041] The scope of protection of this patent includes, but is not limited to, the above-described embodiments. The scope of protection of this patent is determined by the claims. Any substitutions, modifications, or improvements to this technology that are easily conceived by those skilled in the art shall fall within the scope of protection of this patent.

Claims

1. A semi-closed hydraulic system driven by an electric motor, comprising a double-acting piston cylinder having a rod chamber and a rodless chamber; characterized in that: The rod chamber of the hydraulic cylinder is connected to the first inlet / outlet of the hydraulic pump / motor via the first oil circuit, and the rodless chamber of the hydraulic cylinder is connected to the second inlet / outlet of the hydraulic pump / motor via the second oil circuit; the motor is directly or indirectly connected to the hydraulic pump / motor; the two inlets of the drain direction control valve are connected to the first oil circuit and the second oil circuit respectively, and the outlet of the drain direction control valve is connected to the oil tank via the drain pressure stabilizing valve; the drain direction control valve connects the oil circuit with lower pressure between the first and second oil circuits to the drain pressure stabilizing valve; the replenishment oil circuit for replenishing oil to the first or second oil circuit is connected to the first and second oil circuits respectively via a replenishment check valve.

2. The semi-closed hydraulic system with a motor-driven hydraulic cylinder as described in claim 1, characterized in that: The replenishment circuit includes a replenishment pump that rotates under the drive of a replenishment motor. The outlet of the replenishment pump is connected to the first oil circuit and the second oil circuit through replenishment check valves.

3. The semi-closed hydraulic system with a motor-driven hydraulic cylinder as described in claim 2, characterized in that: The outlet of the replenishment pump is connected to the oil tank via an overflow valve.

4. The semi-closed hydraulic system with a motor-driven hydraulic cylinder as described in claim 1, characterized in that: The first and second oil lines are connected to the oil tank via overflow valves.

5. The semi-closed hydraulic system with a motor-driven hydraulic cylinder as described in any one of claims 1-4, characterized in that: Hydraulic pumps / motors: constant displacement pumps or variable displacement pumps.

6. The semi-closed hydraulic system with a motor-driven hydraulic cylinder as described in any one of claims 1-4, characterized in that: When used as a pump, the hydraulic pump / motor pumps hydraulic oil into the cylinder under the drive of the motor. When used as a motor, the cylinder drives the hydraulic pump / motor through the hydraulic oil, thereby driving the motor to generate electricity and realizing the recovery of kinetic and potential energy.

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