A pure electric loader positive flow hydraulic system and a pure electric loader

Abstract

The application discloses a pure electric loader positive flow hydraulic system and a pure electric loader, wherein an oil outlet of a working pump is connected with an oil inlet P1 of a multi-way valve; an oil outlet of a steering pump is connected with an oil inlet P of a flow amplification valve, and an oil outlet PF of the flow amplification valve is connected with an oil inlet P2 of the multi-way valve; the oil outlet of the steering pump is connected with an oil inlet P of a pilot oil source valve, an oil outlet U of the pilot oil source valve is connected with an oil inlet P of an electric proportional pressure reducing valve, and each output port of the electric proportional pressure reducing valve is connected with a corresponding pilot control port of the multi-way valve; an electric control handle is connected with a controller, and the controller is connected with the electric proportional pressure reducing valve and a hydraulic motor; the controller is connected with the oil inlet P2 of the multi-way valve through a pressure sensor; the working pump and the steering pump are controlled by the multi-way valve, and meanwhile, the controller matches the rotating speed of the hydraulic motor according to the pilot control signal of the electric proportional pressure reducing valve and the input signal of the electric control handle. The application realizes that the working pump and the steering pump are respectively controlled by two shunt valves in the multi-way valve, and the matching of the pilot control signal and the rotating speed of the motor, so that the throttling loss of the whole machine in the working process is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electric loaders, and particularly relates to a positive flow hydraulic system of a pure electric loader and the pure electric loader. BACKGROUND

[0002] In the prior art, due to the speed regulation characteristics of a variable frequency motor, an electric loader usually adopts a single motor to drive a constant flow pump through motor speed regulation. However, due to the characteristics of the constant flow pump, it cannot work at too low speed, and thus a minimum speed needs to be given. At the minimum speed, more throttling loss will be generated in the whole vehicle movement process. Meanwhile, when the system pressure is reached and the pump port needs to be pressure maintained, a certain speed also needs to be maintained to continuously output flow, which all causes excessive energy loss and affects the endurance of the whole machine. SUMMARY

[0003] To solve the problems in the prior art, the present application provides a positive flow hydraulic system of a pure electric loader and the pure electric loader. The working pump and the steering pump are respectively controlled by two shunt valves in a multi-way valve, and are matched with a pilot control signal and a motor speed, so as to greatly reduce the throttling loss of the whole machine in the working process.

[0004] To achieve the above-mentioned purposes, the technical scheme adopted by the present application is as follows:

[0005] In a first aspect, a positive flow hydraulic system of a pure electric loader is provided, comprising: a working pump, a steering pump, and a hydraulic motor for driving the working pump and the steering pump to work; an oil outlet of the working pump is connected with an oil inlet P1 of a multi-way valve; an oil outlet of the steering pump is connected with an oil inlet P of a flow amplification valve, and an oil outlet PF of the flow amplification valve is connected with an oil inlet P2 of the multi-way valve; the oil outlet of the steering pump is connected with an oil inlet P of a pilot oil source valve, and an oil outlet U of the pilot oil source valve is connected with an oil inlet P of an electric proportional pressure reducing valve, and each output port of the electric proportional pressure reducing valve is connected with a corresponding pilot control port of the multi-way valve; an electric control handle is connected with a controller, and the controller is connected with the electric proportional pressure reducing valve and the hydraulic motor; the controller is connected with the oil inlet P2 of the multi-way valve through a pressure sensor; the working pump and the steering pump are controlled by the multi-way valve, and the controller matches the speed of the hydraulic motor according to the pilot control signal of the electric proportional pressure reducing valve and the input signal of the electric control handle, so as to reduce the throttling loss of the whole machine in the working process.

[0006] Further, the oil outlet U of the pilot oil source valve is connected with an oil inlet P of a steering gear, a left steering oil port L of the steering gear is connected with a left steering oil port L of the flow amplification valve through a limiting valve two, and a right steering oil port R of the steering gear is connected with a right steering oil port R of the flow amplification valve through a limiting valve one.

[0007] Furthermore, the working oil port of the flow amplification valve is connected to the steering cylinder; the working oil port 1 of the multi-way valve is connected to the bucket cylinder, and the working oil port 2 of the multi-way valve is connected to the boom cylinder.

[0008] Furthermore, the multi-way valve includes a working pump diverter valve, a steering pump diverter valve, a one-way valve, an LS overflow valve, a main safety valve and an LS damper; the oil inlet P2 of the multi-way valve is respectively connected to the oil inlet of the main safety valve, the oil inlet of the steering pump diverter valve and the oil outlet of the one-way valve; the oil inlet P1 of the multi-way valve is respectively connected to the oil inlet of the working pump diverter valve and the oil inlet of the one-way valve; the non-spring chamber of the working pump diverter valve is connected to the oil inlet of the steering pump diverter valve; the spring chamber of the working pump diverter valve is respectively connected to the spring chamber of the steering pump diverter valve, the oil inlet of the LS overflow valve and one end of the LS damper; the oil outlet of the working pump diverter valve, the oil outlet of the steering pump diverter valve, the oil outlet of the main safety valve and the oil outlet of the LS overflow valve are respectively connected to the oil return port T of the multi-way valve.

[0009] Furthermore, the switching control pressure Δp1 of the working pump diverter valve is smaller than the control pressure Δp2 of the steering pump diverter valve.

[0010] Furthermore, the set pressure p1 of the LS relief valve and the set pressure p2 of the main safety valve satisfy: p1 < (p2 - Δp2).

[0011] Furthermore, when the vehicle is idling, the hydraulic oil output by the steering pump enters the oil inlet P2 of the multi-way valve and returns through the steering pump diverter valve, and the hydraulic oil output by the working pump enters the oil inlet P1 of the multi-way valve and returns through the working pump diverter valve.

[0012] Furthermore, when the electric control handle controls the valve core of the multi-way valve to switch direction, the speed control of the hydraulic motor satisfies the following requirements: after the steering pump diverter valve and the working pump diverter valve are completely closed, the speed of the hydraulic motor is increased.

[0013] Furthermore, when the electric control handle controls the valve core of the multi-way valve to switch direction, when the steering pump diverter valve and the working pump diverter valve are completely closed, the speed change of the hydraulic motor satisfies:

[0014]

[0015] in, is the displacement of the working pump; is the displacement of the steering pump; is the fluid flow coefficient; A is the area of ​​the oil inlet ports P1 and P2 → each working oil port during the spool reversing process of the multi-way valve; It is the switching control pressure of the diverter valve of the working pump; is the hydraulic oil density.

[0016] Furthermore, when the pressure at the oil inlet P2 of the multi-way valve reaches p1+Δp2, the pressure sensor transmits a signal to the controller, and the controller reduces the speed of the hydraulic motor to idle speed.

[0017] In a second aspect, a pure electric loader is provided, wherein the pure electric loader is equipped with the pure electric loader positive flow hydraulic system described in the first aspect.

[0018] Compared with the prior art, the present invention has the following beneficial effects: the present invention connects the oil outlet of the working pump with the oil inlet P1 of the multi-way valve; the oil outlet of the steering pump is connected with the oil inlet P of the flow amplification valve, the oil outlet PF of the flow amplification valve is connected with the oil inlet P2 of the multi-way valve; the oil outlet of the steering pump is connected with the oil inlet P of the pilot oil source valve, the oil outlet U of the pilot oil source valve is connected with the oil inlet P of the electric proportional pressure reducing valve, and each output port of the electric proportional pressure reducing valve is respectively connected with the corresponding pilot control port of the multi-way valve; the electric control handle is connected to the controller The controller is connected to the electric proportional pressure reducing valve and the hydraulic motor respectively; the controller is connected to the oil inlet P2 of the multi-way valve through a pressure sensor; the working pump and the steering pump are shunted and controlled by the multi-way valve. At the same time, the controller matches the speed of the hydraulic motor according to the pilot control signal of the electric proportional pressure reducing valve and the input signal of the electric control handle, so that the working pump and the steering pump are shunted and controlled by the two shunt valves in the multi-way valve respectively, and combined with the matching of the pilot control signal and the motor speed, the throttling loss of the whole machine during operation is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the principle of a positive flow hydraulic system for a pure electric loader provided by an embodiment of the present invention;

[0020] In the figure: 1. Working pump; 2. Steering pump; 3. Hydraulic motor; 4. Steering gear; 51. Limit valve 1; 52. Limit valve 2; 6. Flow amplification valve; 7. Steering cylinder; 8. Pressure sensor; 9. Controller; 10. Electric control handle; 11. Pilot oil source valve; 12. Electric proportional pressure reducing valve; 13. Boom cylinder; 14. Bucket cylinder; 15. Multi-way valve; 151. Working pump diverter valve; 152. Steering pump diverter valve; 153. Check valve; 154. LS overflow valve; 155. Main safety valve; 156. LS damper. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0022] Example 1:

[0023] like Figure 1As shown, a positive flow hydraulic system for a pure electric loader, in which a hydraulic motor 3 simultaneously drives a working pump 1 and a steering pump 2. The oil outlet of the working pump 1 is connected to the oil inlet P1 of the multi-way valve 15; the oil outlet of the steering pump 2 is connected to the oil inlet P of the flow amplification valve 6, and the oil outlet PF of the flow amplification valve 6 is connected to the oil inlet P2 of the multi-way valve 15; the oil outlet of the steering pump 2 is connected to the oil inlet P of the pilot oil source valve 11, and the oil outlet U of the pilot oil source valve 11 is connected to the oil inlet P of the electric proportional pressure reducing valve 12. The output ports of the electric proportional pressure reducing valve 12 are respectively connected to the corresponding pilot control ports (a1, a2, b 1, b2); the electric control handle 10 is connected to the controller 9, and the controller 9 is respectively connected to the electric proportional pressure reducing valve 12 and the hydraulic motor 3; the controller 9 is connected to the oil inlet P2 of the multi-way valve 15 through the pressure sensor 8; the working pump 1 and the steering pump 2 are shunted and controlled by the multi-way valve 15. At the same time, the controller 9 matches the speed of the hydraulic motor 3 according to the pilot control signal of the electric proportional pressure reducing valve 12 and the input signal of the electric control handle 10, so as to reduce throttling losses of the entire machine during operation.

[0024] The oil outlet U of the pilot oil source valve 11 is connected to the oil inlet P of the steering gear 4. The left steering oil port L of the steering gear 4 is connected to the left steering oil port L of the flow amplification valve 6 through the limit valve 2 52. The right steering oil port R of the steering gear 4 is connected to the right steering oil port R of the flow amplification valve 6 through the limit valve 1 51.

[0025] The working oil port of the flow amplification valve 6 is connected to the steering cylinder 7; the working oil port 1 of the multi-way valve 15 is connected to the bucket cylinder 14, and the working oil port 2 of the multi-way valve 15 is connected to the boom cylinder 13.

[0026] The multi-way valve 15 is a load-sensitive multi-way valve, including a working pump diverter valve 151, a steering pump diverter valve 152, a one-way valve 153, an LS relief valve 154, a main safety valve 155 and an LS damper 156; the oil inlet P2 of the multi-way valve 15 is connected to the oil inlet of the main safety valve 155, the oil inlet of the steering pump diverter valve 152 and the oil outlet of the one-way valve 153; the oil inlet P1 of the multi-way valve 15 is connected to the oil inlet of the working pump diverter valve 151, the oil inlet of the one-way valve 153 and the oil outlet of the one-way valve 156. The non-spring chamber of the working pump diverter valve 151 is connected to the oil inlet of the steering pump diverter valve 152; the spring chamber of the working pump diverter valve 151 is respectively connected to the spring chamber of the steering pump diverter valve 152, the oil inlet of the LS relief valve 154, and one end of the LS damper 156; the oil outlet of the working pump diverter valve 151, the oil outlet of the steering pump diverter valve 152, the oil outlet of the main safety valve 155, and the oil outlet of the LS relief valve 154 are respectively connected to the oil return port T of the multi-way valve 15.

[0027] The switching control pressure Δp1 of the working pump diverter valve 151 should be smaller than the control pressure Δp2 of the steering pump diverter valve 152, and the set pressure p1 of the LS relief valve 154 in the multi-way valve 15 and the set pressure p2 of the main safety valve 155 should satisfy p1<(p2-Δp2).

[0028] When the vehicle is idling, the hydraulic oil output by steering pump 2 enters the oil inlet P2 of multi-way valve 15 and simultaneously acts on the non-spring chambers of working pump diverter valve 151 and steering pump diverter valve 152. When the pressure at oil inlet P2 of multi-way valve 15 reaches the control pressure Δp2 of steering pump diverter valve 152, steering pump diverter valve 152 opens, and steering pump 2 now flows through steering pump diverter valve 152 at a pressure of Δp2. Since the control pressure Δp1 of working pump diverter valve 151 is less than Δp2, working pump diverter valve 151 is fully open. At this time, the hydraulic oil output by working pump 1 passes through working pump diverter valve 151 without throttling losses. This allows steering pump 2 to return oil through steering pump diverter valve 152, while working pump 1 returns oil through working pump diverter valve 151.

[0029] When the entire machine is in operation, the pressure at the oil inlet P2 of the multi-way valve 15 reaches p1+Δp2. At this time, the LS relief valve 154 opens, and a pressure difference of Δp2 is generated through the LS damper 156. At this time, the pressure difference between the non-spring chamber and the spring chamber of the steering pump diverter valve 152 is Δp2. The steering pump 2 passes through the steering pump diverter valve 152 at a pressure of p1+Δp2. Since the control pressure Δp1 of the working pump diverter valve 151 is less than Δp2, the working pump diverter valve 15.2 is fully open. At this time, the hydraulic oil output by the working pump 1 does not need to generate throttling loss to pass through the working pump diverter valve 152.

[0030] When the whole machine is in operation, the electric control handle 10 is operated to control the electric proportional pressure reducing valve 12 to output pilot pressure to each pilot port of the multi-way valve 15 through the controller 9 to control the valve core (that is, the valve core in the multi-way valve that controls the boom cylinder 13 and the bucket cylinder 14) to switch. During the valve core switching process, the valve port area of ​​the oil inlet P1 and P2 of the multi-way valve 15 → each working port gradually increases. As the valve port area increases, the electric control handle 10 controls the change in the speed of the hydraulic motor through the controller 9.

[0031] When the electric control handle 10 controls the valve core of the multi-way valve 15 to switch direction, the speed control of the hydraulic motor 3 satisfies the following requirements: after the steering pump diverter valve 152 and the working pump diverter valve 151 are completely closed, the speed of the hydraulic motor 3 is increased.

[0032] When the electric control handle 10 is operated to control the direction of the multi-way valve 15, as the oil inlet P1 and P2 of the multi-way valve 15 → the valve ports of each working port gradually open, the load pressure p3 is transmitted to the spring chambers of the steering pump diverter valve 152 and the working pump diverter valve 151. At this time, the steering pump diverter valve 152 is in a throttling state, maintaining the multi-way valve 15 The pressure p4 of the oil inlet P2 is equal to p3+Δp2. Part of the hydraulic oil output by the steering pump 2 enters the boom cylinder 13 and / or the bucket cylinder 14 through the valve port of the multi-way valve 15, maintaining the pressure difference before and after the valve port of the multi-way valve 15 at Δp2 and acting on both ends of the steering pump diverter valve 152. The other part is throttled back to oil by the steering pump diverter valve 152. At this time, since the pressure difference between the pressure p4 at the oil inlet P2 of the multi-way valve 15 and the load pressure p3 is Δp2, which is greater than the control pressure Δp1 of the working pump diverter valve 151, the working pump diverter valve 151 is fully opened, and the hydraulic oil output by the working pump 1 enters the oil inlet P1 of the multi-way valve 15 at low pressure and returns to oil through the working pump diverter valve 151, thereby achieving energy saving.

[0033] When the electric control handle 10 is operated to make the multi-way valve 15 continue to change direction, as the oil inlet P1 and P2 of the multi-way valve 15 → the valve ports of each working port gradually increase, all the flow of the steering pump 2 passes through the valve port of the multi-way valve 15 into the boom cylinder 13 and / or bucket cylinder 14. At this time, when the pressure difference before and after the valve port of the multi-way valve 15 is less than Δp2, the steering pump diverter valve 152 is completely closed. When the pressure difference before and after the valve port of the multi-way valve 15 is reduced to Δp1, the working pump diverter valve 151 begins to enter the throttling state, and the pump port pressure of the working pump 1 increases to the pressure p4 of the oil inlet P2 of the multi-way valve 15. Part of the hydraulic oil enters the cylinder (boom cylinder 13 and / or bucket cylinder 14) through the valve port of the multi-way valve 15, and the remaining hydraulic oil is throttled back to oil through the working pump diverter valve 151.

[0034] When the electric control handle 10 is operated to make the multi-way valve 15 continue to change direction, as the oil inlet P1 and P2 of the multi-way valve 15 → the valve ports of each working port further increase, the flow of the working pump 1 and the steering pump 2 all enter the oil cylinder through the valve ports. When the pressure difference before and after the valve port of the multi-way valve 15 is less than Δp1, the steering pump diverter valve 152 and the working pump diverter valve 151 are completely closed. Before this, the hydraulic motor 3 is always in an idling state, avoiding excess flow throttling and returning oil, thereby achieving energy saving.

[0035] When the electric control handle 10 is operated to continue reversing the multi-way valve 15, so that the valve openings of the oil inlet ports P1 and P2 of the multi-way valve 15 → the working ports are increased until the steering pump diverter valve 152 and the working pump diverter valve 151 are completely closed, the speed of the hydraulic motor 3 begins to gradually increase with the increase of the valve opening. During the process of speed increase, the pressure loss of the total flow of the steering pump 2 and the working pump 1 through the valve port of the multi-way valve 15 should be ensured to be less than Δp1, that is, the following relationship is satisfied:

[0036]

[0037] in, is the displacement of working pump 1, mL / r; is the displacement of steering pump 2, mL / r; is the fluid flow coefficient; A is the area of ​​the oil inlet ports P1 and P2 → each working oil port during the valve core reversing process of the multi-way valve 15, m 2 ; is the switching control pressure of the working pump diverter valve 151, MPa; is the density of hydraulic oil, kg / m 3 .

[0038] In addition, when the pressure at the oil inlet P2 of the multi-way valve 15 reaches p1+Δp2, the pressure sensor 8 transmits a signal to the controller 9, and the controller 9 reduces the speed of the hydraulic motor 3 to idle speed. At this time, the working pump 1 returns oil at low pressure, and the steering pump 2 maintains the pressure of p1+Δp2 and returns oil at idle flow rate, further reducing energy loss.

[0039] In this invention, the working pump and steering pump are controlled by two diverter valves in a load-sensing multi-way valve. This, combined with the matching of the pilot control signal with the motor speed, significantly reduces throttling losses during operation. Furthermore, the closed-center multi-way valve employed enables load-independent flow distribution through post-valve compensation.

[0040] Example 2:

[0041] Based on the positive flow hydraulic system for a pure electric loader described in the first embodiment, this embodiment provides a pure electric loader, which is equipped with the positive flow hydraulic system for a pure electric loader described in the first embodiment.

[0042] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A positive flow hydraulic system for a pure electric loader, characterized in that: include: A working pump (1), a steering pump (2), and a hydraulic motor (3) for driving the working pump (1) and the steering pump (2); The oil outlet of the working pump (1) is connected to the oil inlet P1 of the multi-way valve (15); The oil outlet of the steering pump (2) is connected to the oil inlet P of the flow amplification valve (6), and the oil outlet PF of the flow amplification valve (6) is connected to the oil inlet P2 of the multi-way valve (15); The oil outlet of the steering pump (2) is connected to the oil inlet P of the pilot oil source valve (11), the oil outlet U of the pilot oil source valve (11) is connected to the oil inlet P of the electric proportional pressure reducing valve (12), and each output port of the electric proportional pressure reducing valve (12) is respectively connected to the corresponding pilot control port of the multi-way valve (15); The electric control handle (10) is connected to the controller (9), and the controller (9) is connected to the electric proportional pressure reducing valve (12) and the hydraulic motor (3) respectively; the controller (9) is connected to the oil inlet P2 of the multi-way valve (15) through the pressure sensor (8); The working pump (1) and the steering pump (2) are subjected to flow diversion control via a multi-way valve (15). At the same time, the controller (9) matches the speed of the hydraulic motor (3) according to the pilot control signal of the electric proportional pressure reducing valve (12) and the input signal of the electric control handle (10), so as to reduce the throttling loss of the whole machine during operation. The multi-way valve (15) comprises a working pump diverter valve (151), a steering pump diverter valve (152), a one-way valve (153), an LS overflow valve (154), a main safety valve (155) and an LS damper (156); the oil inlet P2 of the multi-way valve (15) is respectively connected to the oil inlet of the main safety valve (155), the oil inlet of the steering pump diverter valve (152) and the oil outlet of the one-way valve (153); the oil inlet P1 of the multi-way valve (15) is respectively connected to the oil inlet of the working pump diverter valve (151) and the oil inlet of the one-way valve (153). The non-spring chamber of the working pump diverter valve (151) is connected to the oil inlet of the steering pump diverter valve (152); the spring chamber of the working pump diverter valve (151) is respectively connected to the spring chamber of the steering pump diverter valve (152), the oil inlet of the LS relief valve (154), and one end of the LS damper (156); the oil outlet of the working pump diverter valve (151), the oil outlet of the steering pump diverter valve (152), the oil outlet of the main safety valve (155), and the oil outlet of the LS relief valve (154) are respectively connected to the oil return port T of the multi-way valve (15); The switching control pressure Δp1 of the working pump diverter valve (151) is smaller than the control pressure Δp2 of the steering pump diverter valve (152); The set pressure p1 of the LS relief valve (154) and the set pressure p2 of the main safety valve (155) satisfy: p1 < (p2 - Δp2); During the process of the electric control handle (10) controlling the valve core of the multi-way valve (15) to switch directions, the speed control of the hydraulic motor (3) satisfies the following conditions: after the steering pump diverter valve (152) and the working pump diverter valve (151) are completely closed, the speed of the hydraulic motor (3) is increased; During the process of the electric control handle (10) controlling the valve core of the multi-way valve (15) to switch directions, when the steering pump diverter valve (152) and the working pump diverter valve (151) are completely closed, the speed change of the hydraulic motor (3) satisfies: ； in, is the displacement of the working pump (1); is the displacement of the steering pump (2); is the fluid flow coefficient; A is the area of ​​the oil inlet ports P1 and P2 → each working oil port during the valve core reversing process of the multi-way valve (15); is the switching control pressure of the working pump diverter valve (151); is the hydraulic oil density.

2. The positive flow hydraulic system of a pure electric loader according to claim 1, characterized in that: The oil outlet U of the pilot oil source valve (11) is connected to the oil inlet P of the steering gear (4), the left steering oil port L of the steering gear (4) is connected to the left steering oil port L of the flow amplification valve (6) through the second limit valve (52), and the right steering oil port R of the steering gear (4) is connected to the right steering oil port R of the flow amplification valve (6) through the first limit valve (51).

3. The positive flow hydraulic system of a pure electric loader according to claim 1, characterized in that: The working oil port of the flow amplification valve (6) is connected to the steering cylinder (7); The working oil port 1 of the multi-way valve (15) is connected to the bucket oil cylinder (14), and the working oil port 2 of the multi-way valve (15) is connected to the boom oil cylinder (13).

4. The positive flow hydraulic system for a pure electric loader according to claim 1, characterized in that: When the vehicle is in an idling state, the hydraulic oil output by the steering pump (2) enters the oil inlet P2 of the multi-way valve (15) and returns through the steering pump diverter valve (152). The hydraulic oil output by the working pump (1) enters the oil inlet P1 of the multi-way valve (15) and returns through the working pump diverter valve (151).

5. The positive flow hydraulic system for a pure electric loader according to claim 1, characterized in that: When the pressure of the oil inlet P2 of the multi-way valve (15) reaches p1+Δp2, the pressure sensor (8) transmits a signal to the controller (9), and the controller reduces the rotation speed of the hydraulic motor (3) to the idle speed.

6. A pure electric loader, characterized in that: The pure electric loader is equipped with the pure electric loader positive flow hydraulic system according to any one of claims 1 to 5.

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