Loader and quantitative hydraulic control system thereof

Abstract

The utility model relates to a loader, in particular to a loader and a quantitative hydraulic control system thereof, which comprises a steering hydraulic system, a working hydraulic system, a control unit and a confluence control valve. The confluence control valve comprises a three-way switching valve and an electromagnetic valve, an oil inlet of the three-way switching valve is connected with an EF port of the priority valve, an oil outlet of the three-way switching valve is connected with an oil inlet of the distribution valve, an oil return port of the three-way switching valve is connected with the hydraulic oil tank, the oil inlet is communicated with the oil outlet in a normal state, and the oil inlet is communicated with the oil return port in a controlled state; the electromagnetic valve is connected with the hydraulic control end of the three-way switching valve; and the control unit is electrically connected with the electromagnetic valve and is configured to control the electromagnetic valve to enable the three-way switching valve to be in a controlled state when the rotating speed of the engine is lower than a preset value, otherwise, the three-way switching valve is in a normal state. In the utility model, the control unit and the confluence control valve are arranged, so that the power absorbed and consumed by the hydraulic system is reduced when the engine runs at a low speed and the working device is operated, and the engine is prevented from flameout.

Description

Technical Field

[0001] The utility model relates to a loader, and more particularly to a loader and a quantitative hydraulic control system thereof. Background Art

[0002] The hydraulic system of the loader includes a steering hydraulic system and a working hydraulic system. In the steering hydraulic system, the steering priority oil supply is usually set. When the working device is in motion, the excess flow of the steering hydraulic system is merged into the working hydraulic system.

[0003] Loader hydraulic systems can be categorized as fully variable, fixed-displacement, and fixed-displacement systems based on the properties of the hydraulic pumps. A fixed-displacement hydraulic system is defined as one in which both the steering and working hydraulic systems are fixed-displacement pumps. In a fixed-displacement hydraulic system, when the working device is in motion, both the fixed-displacement steering pump in the steering hydraulic system and the fixed-displacement working pump in the working hydraulic system operate at full displacement, resulting in the highest power consumption by the hydraulic system. If the machine is operating in high altitude areas and at low engine speeds, this excessive proportion of hydraulic system power to engine power may cause the engine to stall. Utility Model Content

[0004] The technical problem to be solved by the utility model is that the quantitative hydraulic system of a loader may cause the engine to stall when working at full displacement at high altitude and low speed, and provides a loader and a quantitative hydraulic control system thereof.

[0005] The utility model provides a technical solution for achieving its purpose: a quantitative hydraulic control system for a loader, comprising a steering hydraulic system and a working hydraulic system, wherein the steering hydraulic system comprises a steering control device, a priority valve connected to the steering control device, and a steering quantitative pump connected to the priority valve; the working hydraulic system comprises a distribution valve and a working quantitative pump connected to the distribution valve; and the quantitative hydraulic control system further comprises a control unit and a confluence control valve.

[0006] The confluence control valve comprises:

[0007] A three-way switching valve, whose oil inlet is connected to the EF port of the priority valve, the oil outlet is connected to the oil inlet of the distribution valve, and the oil return port is connected to the hydraulic oil tank. When it is normal, the oil inlet and the oil outlet are connected, and when it is controlled, the oil inlet and the oil return port are connected;

[0008] A solenoid valve is connected to the hydraulic control end of the three-way switching valve;

[0009] The control unit is electrically connected to the electromagnetic valve and the engine speed detection device and controls the electromagnetic valve to put the three-way switching valve in a controlled state when the engine speed is lower than a predetermined value, and otherwise puts the three-way switching valve in a normal state.

[0010] In the utility model, a control unit and a confluence control valve are provided. When the engine speed is greater than a predetermined value, the steering hydraulic system and the working hydraulic system merge. When the engine speed is lower than a predetermined value, the confluence control valve disconnects the confluence between the steering hydraulic system and the working hydraulic system. When the steering hydraulic system is not steering, it flows to the hydraulic oil tank through the EF port of the priority valve and the confluence control valve, thereby realizing low-pressure unloading of the steering hydraulic system. At this time, if the working device is heavy, only the working metering pump runs at full displacement, thereby reducing the power absorbed and consumed by the hydraulic system when the engine is running at a low speed and the working device is operated, thereby preventing the engine from stalling.

[0011] In the quantitative hydraulic control system of the loader, the solenoid valve is a two-position three-way valve, whose oil inlet is connected to the pressure oil source, the oil outlet is connected to the hydraulic control end of the three-way switching valve, and the oil return port is connected to the hydraulic oil tank. When the solenoid valve is energized, the oil inlet and the oil outlet are connected, and when the power is off, the oil outlet and the oil return port are connected.

[0012] In the loader quantitative hydraulic control system, the pressure oil source includes a pressure reducing valve, the oil outlet of the pressure reducing valve is connected to the oil inlet of the solenoid valve, and the oil inlet of the pressure reducing valve is connected to the pump port oil circuit of the steering quantitative pump or the working quantitative pump.

[0013] In the quantitative hydraulic control system of the loader, the hydraulic control end of the three-way switching valve is connected to the pump port oil circuit of the steering quantitative pump or the oil outlet of the three-way switching valve through the throttle valve;

[0014] The solenoid valve is a two-way switching valve, whose oil inlet end is connected to the hydraulic control end of the three-way switching valve, and the oil outlet end is connected to the oil return port of the three-way switching valve. When power is supplied, the oil inlet end and the oil outlet end are connected, and when power is off, the oil inlet end and the oil outlet end are cut off.

[0015] In the quantitative hydraulic control system of the loader, each main valve in the distribution valve is set to an open center position.

[0016] In the loader quantitative hydraulic control system, the steering quantitative pump and / or the working quantitative pump is a gear pump.

[0017] In the loader quantitative hydraulic control system, the steering control device includes a steering gear and a steering cylinder connected to the steering gear. The oil inlet and LS port of the steering gear are correspondingly connected to the CF port and LS port of the priority valve.

[0018] The technical solution for achieving the purpose of the utility model is: a loader having the aforementioned loader quantitative hydraulic control system.

[0019] Compared with the prior art, the present invention provides a control unit and a confluence control valve to reduce the power absorbed and consumed by the hydraulic system when the engine is running at a low speed and the working device is operating, thereby preventing the engine from stalling. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a principle diagram of the quantitative hydraulic control system of the utility model loader.

[0021] Figure 2 This is the second principle diagram of the quantitative hydraulic control system of the loader of the utility model.

[0022] Parts names and serial numbers in the figure:

[0023] Hydraulic oil tank 1, working metering pump 2, distribution valve 3, boom cylinder 4, bucket cylinder 5, confluence control valve 6, three-way switching valve 61, solenoid valve 62, pressure reducing valve 7, steering metering pump 8, priority valve 9, steering gear 10, steering cylinder 11. DETAILED DESCRIPTION

[0024] The specific implementation scheme is described below with reference to the accompanying drawings.

[0025] like Figure 1 As shown, the loader's quantitative hydraulic control system includes a steering hydraulic system and a working hydraulic system. The steering hydraulic system and the working hydraulic system are connected via a confluence control valve 6. A control unit (not shown) is electrically connected to the confluence control valve and the engine speed detection device to control the confluence control valve 6 to determine whether the steering hydraulic system and the working hydraulic system merge and supply oil. The steering quantitative pump 8 and / or the working quantitative pump 2 are gear pumps. The engine speed detection device can be an engine speed sensor or an engine control unit (ECU), which can detect or obtain engine speed parameter data.

[0026] The steering hydraulic system includes a steering control device, a priority valve 9 connected to the steering control device, and a steering metering pump 8 connected to the priority valve 9. The steering metering pump 8 is a gear pump.

[0027] The steering control device includes a steering gear 10 and a steering cylinder 11 connected to the steering gear 10. The oil inlet of the steering gear 10 is connected to the CF port of the priority valve 9, and the LS port of the steering gear 10 is correspondingly connected to the LS port of the priority valve 9. During steering action, the steering gear 10 transmits a steering load signal through the LS port to the priority valve 9. The priority valve 9 preferentially supplies steering working pressure oil to the steering gear 10 from the CF port. The excess flow of the priority valve 9 flows from its EF port to the converging control valve 6.

[0028] The steering control device can also be in other forms, such as a combination of a steering gear and a flow amplification valve commonly found in the industry, with the steering cylinder 11 connected to the flow amplification valve. The steering gear is connected to the flow amplification valve to control the flow amplification valve, which in turn controls the extension and retraction of the steering cylinder.

[0029] The working hydraulic system includes a distribution valve 3 and a working metering pump 2 connected to the distribution valve 3. Hydraulic actuators in the working device, such as the boom cylinder 4 and bucket cylinder 5, are connected to the distribution valve 3. The distribution valve 3 includes multiple main valves, such as a boom and bucket main valves, each controlling a corresponding hydraulic actuator. In this embodiment, each main valve in the distribution valve 3 is in an open neutral position. That is, when each main valve is in the neutral position, the working oil inlet and return port of the main valve are connected. When all main valves are in the neutral position, the oil inlet of the multi-way valve is connected to the oil inlet, and the multi-way valve can unload the working metering pump.

[0030] The steering hydraulic system and the working hydraulic system are connected via a merging control valve 6 , and the control unit controls the merging control valve 6 .

[0031] The confluence control valve 6 includes a three-way switching valve 61 and a solenoid valve 62 .

[0032] The oil inlet of the three-way switching valve 61 is connected to the EF port of the priority valve 9, the oil outlet is connected to the oil inlet of the distribution valve 3, and the oil return port is connected to the hydraulic oil tank 1. In normal state, the oil inlet (P port) and the oil outlet (A port) are connected, and when controlled, the oil inlet (P port) and the oil return port (T port) are connected.

[0033] The solenoid valve 62 is connected to the hydraulically controlled end of the three-way switching valve 61. A control unit is electrically connected to the solenoid valve 62 and an engine speed detection device (not shown). When the engine speed falls below a predetermined value, the control unit controls the solenoid valve 62 to place the three-way switching valve 61 in a controlled state. Otherwise, the three-way switching valve 61 is in a normal state. The engine speed detection device can be an engine speed sensor or an engine control unit (ECU), which can detect or obtain engine speed parameter data.

[0034] In this embodiment, a control unit and a confluence control valve 6 are provided. The control unit is associated with the engine speed and can be a whole-machine controller. It obtains the engine speed via a speed sensor or an engine control unit (ECU) and outputs a control current to the solenoid valve based on whether the engine speed exceeds a predetermined value. When the engine speed exceeds the predetermined value, the control unit controls the solenoid valve 62 to set the three-way switching valve 61 to its normal state. This connects the oil inlet and oil outlet of the three-way switching valve 61, allowing the steering hydraulic system and the working hydraulic system to merge. When the engine speed is below the predetermined value, the control unit controls the solenoid valve 62 to set the three-way switching valve 61 to its controlled state. This connects the oil inlet and oil return port of the three-way switching valve 61, allowing the steering hydraulic system and the working hydraulic system to operate independently. The working hydraulic system is supplied with oil by the working metering pump, while the steering hydraulic system is supplied with oil by the steering metering pump. When there is no steering action, the oil output from the steering metering pump flows back to the hydraulic tank through the EF port of the priority valve and the three-way switching valve 61, achieving low-pressure unloading. At this time, the power consumed by the hydraulic system of the loader mainly comes from the working metering pump 2, which avoids the hydraulic system power accounting for too large a proportion of the engine power and causing the engine to stall.

[0035] Alternatively, as Figure 1 As shown, solenoid valve 62 is a two-position, three-way valve with its oil inlet connected to the pressure oil source and its oil outlet connected to the hydraulic control end of three-way switching valve 61. When solenoid valve 62 is energized, the oil inlet and oil outlet are connected; when de-energized, the oil outlet and oil return port are connected. In this scheme, if the engine speed is below a predetermined value, the control unit outputs a control current to solenoid valve 62, and both solenoid valve 62 and three-way switching valve 61 are in the upper position. The combined oil circuit between the steering hydraulic system and the working hydraulic system is blocked, and each system supplies oil independently. When the engine speed is above the predetermined value, the control unit does not output a control current to solenoid valve 62, and both solenoid valve 62 and three-way switching valve 61 are in the lower position, and the steering hydraulic system supplies oil to the combined circuit of the working hydraulic system.

[0036] Optionally, the pressure oil source includes a pressure reducing valve 7, the oil outlet of the pressure reducing valve 7 is connected to the oil inlet of the solenoid valve 62, and the oil inlet of the pressure reducing valve 7 is connected to the pump port of the steering metering pump 8 through an oil circuit, or can be connected to the pump port oil circuit of the working metering pump 2, for example, connected to the oil outlet of the three-way switching valve 62. The pump port of the steering metering pump 8 is connected to the priority valve through a pump oil circuit. The pressure oil source can also be a pilot pressure oil source for the pilot control of the loader, such as the loader's pilot pump or the pilot oil supply valve in the hydraulic system.

[0037] Figure 2 Another confluence control valve in this embodiment is shown. Figure 2As shown, the hydraulic control end of the three-way switching valve 61 is connected to the pump port of the steering metering pump 8 via a throttle valve 63. The hydraulic control end of the three-way switching valve 61 can also be connected to the oil outlet of the three-way switching valve 61 via the throttle valve 63. The oil outlet of the three-way switching valve 61 is connected to the pump port of the working metering pump. When the distribution valve is in the reversing position (the working device is operating), the oil outlet of the three-way switching valve 61 always maintains the working pressure.

[0038] Solenoid valve 62 is a two-way on-off valve. Its oil inlet is connected to the hydraulic control port of three-way switching valve 61, and its oil outlet is connected to the oil return port of three-way switching valve 61. When energized, the oil inlet and oil outlet are connected; when de-energized, the oil inlet and oil outlet are blocked. In this embodiment, under normal conditions, solenoid valve 62 is de-energized, with its oil inlet and oil outlet blocked. Working pressure oil from the steering metering pump 8 or the oil outlet of three-way switching valve 61 (the working metering pump) enters the hydraulic control port of three-way switching valve 61 through throttle valve 63, keeping three-way switching valve 61 in its normal state. When the engine speed falls below a predetermined value, the control unit outputs a control current to solenoid valve 62, turning it on. The hydraulic control port of three-way switching valve 61 is de-pressurized through solenoid valve 62, and the three-way switching valve 61 is in the upper position due to the spring force in the spring chamber. Its oil inlet and oil return port are connected, thus shutting off the combined oil supply from the steering hydraulic system to the working hydraulic system.

[0039] This embodiment also provides a loader having the aforementioned loader quantitative hydraulic control system.

[0040] In the utility model, a control unit and a confluence control valve are provided to reduce the power absorbed and consumed by the hydraulic system when the engine is running at a low speed and the working device is operating, thereby preventing the engine from stalling.

Claims

1. A quantitative hydraulic control system for a loader, comprising a steering hydraulic system and a working hydraulic system, wherein the steering hydraulic system comprises a steering control device, a priority valve connected to the steering control device, and a steering quantitative pump connected to the priority valve; the working hydraulic system comprises a distribution valve and a working quantitative pump connected to the distribution valve; characterized in that: It also includes a control unit and a confluence control valve; The confluence control valve comprises: A three-way switching valve, whose oil inlet is connected to the EF port of the priority valve, the oil outlet is connected to the oil inlet of the distribution valve, and the oil return port is connected to the hydraulic oil tank. When it is normal, the oil inlet and the oil outlet are connected, and when it is controlled, the oil inlet and the oil return port are connected; A solenoid valve is connected to the hydraulic control end of the three-way switching valve; The control unit is electrically connected to the electromagnetic valve and the engine speed detection device and controls the electromagnetic valve to put the three-way switching valve in a controlled state when the engine speed is lower than a predetermined value, and otherwise puts the three-way switching valve in a normal state.

2. The quantitative hydraulic control system for a loader according to claim 1, characterized in that: The solenoid valve is a two-position three-way valve, whose oil inlet is connected to the pressure oil source, the oil outlet is connected to the hydraulic control end of the three-way switching valve, and the oil return port is connected to the hydraulic oil tank. When the solenoid valve is energized, the oil inlet and the oil outlet are connected, and when the power is off, the oil outlet and the oil return port are connected.

3. The quantitative hydraulic control system for a loader according to claim 2, characterized in that: The pressure oil source includes a pressure reducing valve, the oil outlet of the pressure reducing valve is connected to the oil inlet of the solenoid valve, and the oil inlet of the pressure reducing valve is connected to the pump port oil circuit of the steering metering pump.

4. The quantitative hydraulic control system for a loader according to claim 2, characterized in that: The hydraulic control end of the three-way switching valve is connected to the pump port oil circuit of the steering quantitative pump or the oil outlet of the three-way switching valve through a throttle valve; The solenoid valve is a two-way switching valve, whose oil inlet end is connected to the hydraulic control end of the three-way switching valve, and the oil outlet end is connected to the oil return port of the three-way switching valve. When power is supplied, the oil inlet end and the oil outlet end are connected, and when power is off, the oil inlet end and the oil outlet end are cut off.

5. The quantitative hydraulic control system for a loader according to any one of claims 1 to 4, characterized in that: Each main valve in the distribution valve is set to an open center position.

6. The quantitative hydraulic control system for a loader according to any one of claims 1 to 4, characterized in that: The steering metering pump and / or the working metering pump is a gear pump.

7. The quantitative hydraulic control system for a loader according to claim 1, characterized in that: The steering control device includes a steering gear and a steering oil cylinder connected to the steering gear. The oil inlet and LS port of the steering gear are connected to the CF port and LS port of the priority valve correspondingly.

8. A loader, characterized in that: A loader quantitative hydraulic control system according to any one of claims 1 to 7.

Images