Loader and hydraulic system thereof

Abstract

The utility model relates to a hydraulic system, in particular to a loading machine and a hydraulic system thereof, and the hydraulic system of the loading machine comprises a working hydraulic system, a steering hydraulic system, a flow collecting valve and a valve control device. An EF oil port of the flow amplification valve is communicated with an oil inlet of the distribution valve; the quantitative working pump is connected with an oil inlet of the distribution valve through the flow combining valve; and the valve control device is connected with the auxiliary control device and the control end of the flow collecting valve, and is configured to control the flow collecting valve to cut off an oil path from the quantitative working pump to the oil inlet of the distribution valve during reversing of the auxiliary main valve. According to the loading machine, when only the accessory device acts, the flow collecting valve is closed, the quantitative working pump and the quantitative steering pump cannot supply oil to the accessory device in a combined mode, excessive pressure oil supply caused by the fact that double pumps supply oil to the accessory main valve in a flow collecting mode is avoided, and energy consumption of the loading machine is reduced.

Description

Technical Field

[0001] The utility model relates to a hydraulic system, and more specifically to a loader and its hydraulic system. Background Art

[0002] The hydraulic system of a loader includes a steering hydraulic system and a working hydraulic system. Each of the steering hydraulic system and the working hydraulic system has a hydraulic pump as a pressure oil source. To improve the utilization rate of the hydraulic pump, the steering hydraulic system and the working hydraulic system usually adopt a confluence oil supply structure. In the steering hydraulic system, the steering pump preferentially supplies pressure oil to the hydraulic actuator in the steering hydraulic system, and its surplus flow then flows to the working hydraulic system and confluences with the working pump in the working hydraulic system to supply oil to the hydraulic actuator in the working device.

[0003] In some loaders, both the steering pump and the working pump adopt gear pumps. The gear pump is a fixed-displacement pump, its displacement is non-adjustable, and the output flow is related to the rotational speed. In addition, in the working hydraulic system of the loader, in addition to hydraulic actuators such as boom cylinders and bucket cylinders, auxiliary devices may usually be equipped. The hydraulic actuator of the auxiliary device usually has a small flow rate. When only the auxiliary device of the loader is working, the steering pump and the working pump confluence to supply oil to it, and there is too much surplus in the flow rate. The surplus flow can only be consumed by overflow through the overflow valve. The high-pressure overflow of the hydraulic system causes energy loss of the loader and high energy consumption. Summary of the Utility Model

[0004] The technical problem to be solved by the utility model is the energy consumption problem of the existing loader with a fixed-displacement hydraulic system when only the auxiliary device is working, and to provide a loader and its hydraulic system.

[0005] The technical solution for the utility model to achieve its purpose is: a loader hydraulic system, including:

[0006] A working hydraulic system, which has a distribution valve, a fixed-displacement working pump, and an auxiliary control device; the distribution valve has an auxiliary main valve for controlling the hydraulic actuator of the auxiliary device, and the auxiliary control device is used to control the commutation of the auxiliary main valve;

[0007] A steering hydraulic system, which has a fixed-displacement steering pump connected to a flow amplification valve; the EF oil port of the flow amplification valve is communicated with the oil inlet of the distribution valve;

[0008] In addition, the loader hydraulic system further includes a confluence valve and a control valve device;

[0009] The fixed-displacement working pump is connected to the oil inlet of the distribution valve through the confluence valve;

[0010] The control valve device is connected to the auxiliary control device and the control end of the confluence valve, and is configured to control the confluence valve to cut off the oil path from the metering working pump to the oil inlet of the distribution valve when the auxiliary-connected main valve changes direction.

[0011] In the hydraulic system of the loader of the present utility model, the confluence valve is a two-position three-way valve, and its oil inlet, oil outlet and oil drain port are respectively communicated with the metering working pump, the distribution valve and the hydraulic oil tank, and the oil inlet is selectively communicated with the oil outlet or the oil drain port.

[0012] In the hydraulic system of the loader of the present utility model, the confluence valve includes a hydraulically controlled switch valve connected between the metering working pump and the distribution valve and a hydraulically controlled unloading valve connected between the metering working pump and the hydraulic oil tank.

[0013] In the hydraulic system of the loader of the present utility model, the auxiliary-connected main valve is a hydraulically controlled valve; the control valve device includes a shuttle valve, two inlet ends of the shuttle valve are respectively connected to two hydraulically controlled ends of the auxiliary-connected main valve, and an outlet end of the shuttle valve is communicated with the control end of the confluence valve.

[0014] In the hydraulic system of the loader of the present utility model, the control valve device further includes an enabling switch valve, and the shuttle valve is connected to the control end of the confluence valve through the enabling switch valve.

[0015] In the hydraulic system of the loader of the present utility model, the auxiliary control device includes an auxiliary-connected pilot valve connected to the hydraulically controlled end of the auxiliary-connected main valve.

[0016] In the hydraulic system of the loader of the present utility model, the hydraulic system of the loader further includes a pilot oil supply valve, an inlet end of the pilot oil supply valve is communicated with the metering steering pump, and an outlet of the pilot oil supply valve is connected to the oil inlet of the steering gear of the steering hydraulic system and is connected to the auxiliary-connected pilot valve through a pilot cut-off valve.

[0017] In the hydraulic system of the loader of the present utility model, the auxiliary control device is an electric control device, the control valve device includes an electromagnetic switch valve with an electric control end electrically connected to the auxiliary control device, an outlet end of the electromagnetic switch valve is connected to the confluence valve, and an inlet end is connected to a pilot oil source.

[0018] In the hydraulic system of the loader of the present utility model, both the metering working pump and the metering steering pump are gear pumps.

[0019] The technical solution for the present utility model to achieve its purpose is: a loader having the aforementioned hydraulic system of the loader.

[0020] Compared with the prior art, in the loader of the present utility model, when only the attachment device operates, the confluence valve closes, and the fixed-displacement working pump cannot confluence with the fixed-displacement steering pump to supply oil to the attachment device, avoiding excessive supply of pressure oil caused by the confluence of the two pumps to the attachment main valve, and reducing the energy consumption of the loader. Description of the Drawings

[0021] Figure 1 is the schematic diagram of the hydraulic system of the loader of the present utility model.

[0022] Names and serial numbers of components in the figure:

[0023] Hydraulic oil tank 1, fixed-displacement working pump 2, fixed-displacement steering pump 3, flow amplification valve 4, steering gear 5, steering cylinder 6, distribution valve 7, boom main valve 71, bucket main valve 72, attachment main valve 73, boom cylinder 8, bucket cylinder 9, attachment cylinder 10, pilot valve 11, attachment pilot valve 111, confluence valve 12, enable switch valve 13, shuttle valve 14, pilot oil source valve 15, pilot check valve 16. Detailed Embodiment

[0024] The following describes the specific implementation manner with reference to the drawings.

[0025] As Figure 1 shown, the hydraulic system of the loader in this embodiment includes a working hydraulic system and a steering hydraulic system.

[0026] The working hydraulic system has a distribution valve 7, a fixed-displacement working pump 2, and an attachment control device; the distribution valve 7 has an attachment main valve 73 for controlling the hydraulic actuator of the attachment device, and the attachment control device is used to control the commutation of the attachment main valve 73.

[0027] The steering hydraulic system has a fixed-displacement steering pump 3, a steering gear 5, and a steering cylinder 6 connected to the flow amplification valve 4; the EF oil port of the flow amplification valve 4 is communicated with the oil inlet of the 7 distribution valve

[0028] In addition, the hydraulic system of the loader further includes a confluence valve 12 and a control valve device. The fixed-displacement working pump 2 is connected to the oil inlet of the distribution valve 7 through the confluence valve 12; the control valve device is connected to the attachment control device and the control end of the confluence valve 12, and is configured to control the confluence valve 12 to cut off the oil path from the fixed-displacement working pump 2 to the oil inlet of the distribution valve 7 when the attachment main valve 73 commutes.

[0029] The steering cylinder 6 is connected to the flow amplification valve 4 and is controlled to extend and retract by the flow amplification valve 4. The steering gear 5 is connected to the flow amplification valve 4, outputs pilot pressure oil to control the flow amplification valve 4, and controls the extension and retraction of the steering cylinder 6 by controlling the flow amplification valve 4 to realize the steering operation.

[0030] The fixed-displacement steering pump 3 is connected to the flow amplification valve 4. A priority valve is provided in the flow amplification valve 4. The pressure oil from the fixed-displacement steering pump 3 is preferentially supplied to the steering hydraulic system, and the excess flow is output from the EF oil port of the flow amplification valve 4 and flows to the working hydraulic system for driving the working device of the loader.

[0031] In the working hydraulic system, the distribution valve 7 has a triple main valve, namely the boom main valve 71, the bucket main valve 42, and the accessory main valve 43. The boom main valve 71 and the bucket main valve 72 are respectively used to control the boom cylinder 8 and the bucket cylinder 9, and the accessory main valve 73 is used to control the accessory device that may be assembled. The hydraulic actuators of the accessory device usually have a small flow requirement, such as a small-displacement hydraulic motor, a small hydraulic cylinder, etc. The accessory main valve is controlled to change the direction by the accessory control device.

[0032] The pump port of the fixed-displacement working pump 2 is connected to the oil inlet of the distribution valve 7 through the confluence valve 12. The on-off of the oil circuit between the pump port of the fixed-displacement working pump 2 and the oil inlet of the distribution valve 7 is controlled by the confluence valve 12. When the confluence valve 12 is turned on, the fixed-displacement steering pump 2 and the fixed-displacement working pump 3 supply oil to the distribution valve 7 together. If the confluence valve 12 is cut off, the working oil inlet of the distribution valve 7 is provided by the fixed-displacement steering pump 3.

[0033] The on-off of the confluence valve 12 is controlled by the control valve device. When the accessory control device is manipulated to make the accessory main valve 73 change the direction to realize the action of the hydraulic actuator of the accessory device, such as the accessory cylinder 10 or other types of hydraulic actuators, the control valve device acts correspondingly to cut off the oil circuit between the fixed-displacement working pump 2 and the oil inlet of the distribution valve 7, so that the fixed-displacement working pump 2 and the fixed-displacement steering pump 3 cannot supply oil together, and the distribution valve 7 is only supplied with oil by the fixed-displacement steering pump 3. When the manipulation of the accessory main valve 73 is stopped, the control valve device controls the confluence valve 12 to reset, and the oil circuit from the fixed-displacement working pump 2 to the oil inlet of the distribution valve 7 is turned on, realizing the combined oil supply of the two pumps to the boom cylinder 8 and the bucket cylinder 9 in the working device, so that the working device responds quickly.

[0034] Optionally, the confluence valve 12 is a two-position three-way valve, and its oil inlet, oil outlet, and oil drain port are correspondingly connected to the fixed-displacement working pump 2, the distribution valve 7, and the hydraulic oil tank 1, and the oil inlet is selectively communicated with the oil outlet or the oil drain port. When the confluence valve 12 is in the cut-off state, the fixed-displacement working pump 2 is connected to the hydraulic oil tank 1 through the oil inlet and the oil drain port of the confluence valve 12, and the pressure oil provided by the fixed-displacement working pump 2 flows to the hydraulic oil tank through the confluence valve 12, realizing the low-pressure unloading of the fixed-displacement working pump.

[0035] In this embodiment, the confluence valve 12 may further include a hydraulically controlled switch valve and a hydraulically controlled unloading valve. The hydraulically controlled switch valve is connected between the fixed-displacement working pump and the distribution valve and is used to control the on-off of the oil circuit between the fixed-displacement working pump and the distribution valve. The hydraulically controlled unloading valve is connected between the fixed-displacement working pump and the hydraulic oil tank and is used to unload the fixed-displacement working pump. Both the hydraulically controlled switch valve and the hydraulically controlled unloading valve are controlled by a control valve device. When the hydraulically controlled switch valve is turned on, the hydraulically controlled unloading valve is cut off; when the hydraulically controlled switch valve is cut off, the hydraulically controlled unloading valve opens for unloading.

[0036] As Figure 1 shown, the accessory combined main valve 73 is a hydraulically controlled valve; the control valve device includes a shuttle valve 14. The two oil inlets of the shuttle valve 14 are correspondingly connected to the two hydraulically controlled ends of the accessory combined main valve 73, and the oil outlet of the shuttle valve 14 is communicated with the control end of the confluence valve 12. When the accessory combined main valve 73 is manipulated to change direction, the pilot pressure at its hydraulically controlled end acts on the confluence valve 12 through the shuttle valve 14, causing the confluence valve 12 to change direction and cut off. When the manipulation of the accessory combined main valve 73 stops, there is no pilot pressure at its hydraulically controlled end, and the confluence valve 12 resets and turns on.

[0037] Optionally, the control valve device further includes an enable switch valve 13. The shuttle valve 14 is connected to the control end of the confluence valve 12 through the enable switch valve 13. The enable switch valve 13 can be manually operated to close. When the hydraulic actuator of the accessory device is a hydraulic actuator with a large flow requirement, the enable switch valve 13 can be closed. At this time, the confluence valve 12 will not change direction and cut off due to the manipulation of the accessory control device on the accessory combined main valve 73, so as to meet the requirement of some hydraulic actuators of accessory devices with large flow requirements for the combined operation of the fixed-displacement steering pump and the fixed-displacement working pump.

[0038] Optionally, the accessory control device may be a hydraulic control device, which may be an accessory combined pilot valve 111 included in the pilot valve 11. The accessory combined pilot valve 111 is connected to the hydraulically controlled end of the accessory combined main valve 73.

[0039] The loader hydraulic system further includes a pilot oil supply valve 15. The oil inlet of the pilot oil supply valve 15 is connected to the pump port 3 of the fixed-displacement steering pump. The oil outlet of the pilot oil supply valve 15 is connected to the oil inlet of the steering gear 5 of the steering hydraulic system and is also connected to the accessory combined pilot valve 111 through a pilot cut-off valve 16.

[0040] Optionally, the auxiliary control device may also be an electric control device. For example, the auxiliary control device may include an electric control handle, a controller electrically connected to the electric control handle, and an electro-hydraulic proportional valve electrically connected to the controller. The electro-hydraulic proportional valve is arranged at both hydraulic control ends of the auxiliary combined main valve 73 and is used to control the hydraulic control end pressure of the auxiliary combined main valve 73 to achieve the commutation operation of the auxiliary combined main valve. The electro-hydraulic proportional valve may also be an electromagnet that directly drives the valve stem of the auxiliary combined main valve to move. Further, the control valve device includes an electromagnetic switch valve with an electric control end electrically connected to the auxiliary control device. The oil outlet end of the electromagnetic switch valve is connected to the confluence valve 12, and the oil inlet end is connected to a pilot oil source such as a pilot oil supply valve. The electromagnetic switch valve may be connected to the controller and act in association with the electric control handle for controlling the auxiliary combined main valve.

[0041] Optionally, both the fixed-displacement working pump 2 and the fixed-displacement steering pump 3 are gear pumps.

[0042] This embodiment also provides a wheel loader having the aforementioned wheel loader hydraulic system.

[0043] In the wheel loader of the present utility model, when only the hydraulic actuator of the auxiliary device operates, the confluence valve closes, and the fixed-displacement working pump cannot confluence with the fixed-displacement steering pump to supply oil to the auxiliary device, avoiding excessive supply of pressure oil caused by the double pumps confluence-supplying oil to the auxiliary combined main valve, and reducing the energy consumption of the wheel loader.

Claims

1. A loader hydraulic system, comprising: A working hydraulic system having a distribution valve, a fixed-displacement working pump, and an accessory control device; The distribution valve has an accessory combined main valve for controlling a hydraulic actuator of an accessory device, and the accessory control device is used to control the commutation of the accessory combined main valve; A steering hydraulic system having a fixed-displacement steering pump connected to a flow amplifying valve; an EF oil port of the flow amplifying valve is communicated with an oil inlet of the distribution valve; It is characterized in that the loader hydraulic system further comprises a confluence valve and a control valve device; The fixed-displacement working pump is connected to the oil inlet of the distribution valve through the confluence valve; The control valve device is connected to the accessory control device and a control end of the confluence valve, and is configured to control the confluence valve to cut off the oil path from the fixed-displacement working pump to the oil inlet of the distribution valve when the accessory combined main valve commutates.

2. The loader hydraulic system according to claim 1, characterized in that, The confluence valve is a two-position three-way valve, and its oil inlet, oil outlet, and oil drain port are respectively communicated with the fixed-displacement working pump, the distribution valve, and the hydraulic oil tank, and the oil inlet is selectively communicated with the oil outlet or the oil drain port.

3. The loader hydraulic system according to claim 1, characterized in that, The confluence valve includes a liquid-controlled switch valve connected between the fixed-displacement working pump and the distribution valve and a liquid-controlled unloading valve connected between the fixed-displacement working pump and the hydraulic oil tank.

4. The loader hydraulic system according to any one of claims 1 to 3, characterized in that, The accessory combined main valve is a liquid-controlled valve; the control valve device includes a shuttle valve, two oil inlet ends of the shuttle valve are respectively connected to two liquid-controlled ends of the accessory combined main valve, and an oil outlet end of the shuttle valve is communicated with a control end of the confluence valve.

5. The hydraulic system of a loader according to claim 4, wherein The control valve device further includes an enabling switch valve, and the shuttle valve is connected to the control end of the confluence valve through the enabling switch valve.

6. The loader hydraulic system according to claim 4, wherein, The accessory control device includes an accessory combined pilot valve connected to a liquid-controlled end of the accessory combined main valve.

7. The loader hydraulic system according to claim 6, characterized in that, The loader hydraulic system further includes a pilot oil supply valve, an oil inlet end of the pilot oil supply valve is communicated with the fixed-displacement steering pump, an oil outlet of the pilot oil supply valve is connected to an oil inlet of a steering gear of the steering hydraulic system and is connected to the accessory combined pilot valve through a pilot cut-off valve.

8. The hydraulic system of a loader according to any one of claims 1 to 3, characterized in that, The accessory control device is an electric control device, the control valve device includes an electromagnetic switch valve with an electric control end electrically connected to the accessory control device, an oil outlet end of the electromagnetic switch valve is connected to the confluence valve, and an oil inlet end is connected to a pilot oil source.

9. The hydraulic system of a loader according to claim 1, characterized in that, Both the fixed-displacement working pump and the fixed-displacement steering pump are gear pumps.

10. A loader, characterized in that, A loader hydraulic system according to any one of claims 1 to 9.

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