Loader and hydraulic system thereof

Abstract

The utility model relates to a hydraulic system, in order to solve the problem that when an engine of an existing loader is started, an energy accumulator of a braking system is filled with liquid to increase the starting load of the engine, the hydraulic system of the loader comprises a liquid filling valve, a flow amplifying valve, a two-position three-way valve and a shuttle valve, an oil inlet of the prefill valve is connected with a CF port of a priority valve in the flow amplification valve; an oil inlet, an oil outlet and an oil return port of the two-position three-way valve are correspondingly connected with an S signal port of the prefill valve, a first oil inlet end of the shuttle valve and an oil tank loop, the oil outlet of the two-position three-way valve is selectively communicated with the oil inlet or the oil return port, and an LS1 signal port of the flow amplification valve is communicated with a second oil inlet end of the shuttle valve. And the oil outlet end of the shuttle valve is connected with a control signal port of the priority valve. The hydraulic system of the loader does not have a liquid filling load when the engine is started, and is easy to start.

Description

Technical Field

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

[0002] The loader's hydraulic system primarily consists of the brake hydraulic system, the steering hydraulic system, and the working hydraulic system. In a loader's hydraulic system using a metering pump for oil supply, the brake hydraulic system typically draws pressurized oil from the steering hydraulic system. This system is connected to the CF port of the priority valve in the flow amplifier valve via a charging valve, and is then supplied with oil by the steering pump through the priority valve.

[0003] In the existing loader hydraulic system, when the accumulator pressure in the brake system is low, the charging valve is at the charging position. If the engine is started at this time, the hydraulic pump is driven during the engine startup process. The hydraulic pump frequently fills oil to the charging valve through the priority valve to charge the accumulator. Therefore, the engine is started with load, making it difficult to start the engine. Utility Model Content

[0004] The technical problem to be solved by the utility model is that when the engine of the existing loader is started, the brake system accumulator is filled with liquid to increase the engine starting load, and a loader and a hydraulic system thereof are provided.

[0005] The technical solution for achieving the purpose of the utility model is as follows: a loader hydraulic system is provided, which includes a brake hydraulic system with a filling valve, a steering hydraulic system with a flow amplification valve, and a working hydraulic system with a distribution valve, wherein the oil inlet of the filling valve is connected to the CF port of the priority valve in the flow amplification valve; the EF port of the priority valve is connected to the oil inlet of the distribution valve.

[0006] The loader hydraulic system also includes a two-position three-way valve and a shuttle valve. The oil inlet, oil outlet and oil return port of the two-position three-way valve correspond to the S signal port of the charging valve for outputting the charging pressure signal, the first oil inlet end of the shuttle valve and the oil tank circuit are connected. The oil outlet of the two-position three-way valve is selectively connected to the oil inlet or the oil return port. The LS1 signal port of the flow amplification valve for outputting the steering load feedback pressure is connected to the second oil inlet end of the shuttle valve, and the oil outlet end of the shuttle valve is connected to the control signal port of the priority valve.

[0007] In the hydraulic system of the loader of the present invention, the two-position three-way valve is a solenoid valve. When de-energized, its oil inlet and oil outlet are normally open. When the engine driving the hydraulic pump is started, the two-position three-way valve is de-energized, preventing the filling pressure signal of the filling valve from being transmitted to the control signal port of the priority valve.

[0008] In the loader hydraulic system of the present invention, the two-position, three-way valve is a hydraulically controlled valve. Its hydraulically controlled end is connected to the oil inlet of the flow amplifier valve, and its normal state is that the oil return port is connected to the oil outlet. During the engine startup process, which drives the hydraulic pump, the hydraulic pressure at the two-position, three-way valve is built up, and the two-position, three-way valve is in its normal state, preventing the filling pressure signal from the filling valve from being transmitted to the control signal port of the priority valve.

[0009] In the hydraulic system of a loader of the present utility model, the charging valve includes a relief valve, a reversing valve, a check valve and a throttle valve; the oil inlet of the charging valve is simultaneously connected to the oil inlet end of the check valve and the oil inlet end of the reversing valve, the oil outlet of the charging valve is simultaneously connected to the oil outlet end of the check valve and the hydraulic control end of the relief valve, the hydraulic control end of the reversing valve and the oil inlet end of the relief valve are both connected to the oil outlet end of the check valve through the throttle valve; the oil outlet end of the relief valve and the oil return end of the reversing valve are both connected to the oil return port of the charging valve; the oil outlet end of the reversing valve is connected to the S signal port; the oil outlet end of the reversing valve is selectively connected to the oil inlet end or the oil return end.

[0010] In the hydraulic system of the loader of the utility model, an unloading valve is connected between the EF port of the priority valve and the oil tank circuit.

[0011] The filling valve also includes a second throttle valve, the oil inlet of the filling valve is connected to the oil inlet end of the second throttle valve, and the oil outlet end of the second throttle valve is connected to the oil inlet end of the one-way valve and the oil inlet end of the reversing valve at the same time.

[0012] In the hydraulic system of the loader of the utility model, the hydraulic pump connected to the oil inlet of the flow amplification valve in the steering hydraulic system is a gear pump.

[0013] In the hydraulic system of the loader of the utility model, the hydraulic pump connected to the oil inlet of the distribution valve in the working hydraulic system is a gear pump.

[0014] The technical solution for achieving the purpose of the present invention is as follows: a loader is provided, which has the above-mentioned loader hydraulic system.

[0015] Compared with the prior art, in the hydraulic system of the loader of the present invention, the two-position three-way valve can be controlled so that the hydraulic pump does not supply charging pressure oil to the charging valve through the priority valve when the engine is started, thereby reducing the load on the engine startup and facilitating the engine startup; the shuttle valve is arranged between the two-position three-way valve and the priority valve, and when the two-position three-way valve fails, it can still ensure that the steering load feedback signal is transmitted to the priority valve control signal port to ensure steering. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the hydraulic system of the utility model loader.

[0017] Figure 2 The utility model is a schematic diagram of the oil circuit connection between the filling valve and the flow amplification valve in the hydraulic system of the loader.

[0018] Figure 3 It is a schematic diagram of the oil circuit connection of another embodiment of the liquid filling valve and the flow amplification valve in the hydraulic system of the loader of the utility model.

[0019] Parts names and serial numbers in the figure:

[0020] Filling valve 10 , one-way valve 101 , overflow valve 102 , reversing valve 104 , throttle valve 105 , second throttle valve 106 , parking brake device 11 , accumulator 12 , foot brake valve 13 , service brake 14 .

[0021] Hydraulic oil tank 21, steering pump 22, pilot oil supply valve 23, two-position three-way valve 24, steering gear 25, flow amplification valve 26, priority valve 261, steering cylinder 27, unloading valve 28, shuttle valve 29.

[0022] Pilot valve 30 , working pump 31 , distribution valve 32 , boom cylinder 33 , bucket cylinder 34 , and attachment 35 . DETAILED DESCRIPTION

[0023] The specific implementation scheme is described below with reference to the accompanying drawings.

[0024] This embodiment discloses a loader hydraulic system, which includes a brake hydraulic system, a steering hydraulic system, and a working hydraulic system.

[0025] like Figure 1 As shown, the brake hydraulic system includes a charging valve 10, a parking brake device 11, an accumulator 12, a foot brake valve 13, and a service brake 14. The oil outlet of the charging valve 10 is connected to the parking brake device 11, the accumulator 12, and the foot brake valve 13. The charging valve 10 is used to charge the accumulator 12, and the accumulator 12 is used to provide brake pressure oil to the parking brake device 11 and the foot brake valve 13. The service brake 14 can be applied by stepping on the foot brake valve 13.

[0026] like Figure 2As shown, the charging valve 10 includes a one-way valve 101, a relief valve 102, a reversing valve 104, a throttle valve 105, and a second throttle valve 106. The oil inlet (port P) of the charging valve 10 is connected to both the oil inlet of the one-way valve 101 and the oil inlet (port C) of the reversing valve 104 via the second throttle valve 106. The oil outlet of the charging valve 10 is connected to the oil outlet of the one-way valve 101. The oil outlet of the charging valve 10 is also connected to the hydraulic control end of the relief valve 102 via a ball valve. The hydraulic control port of reversing valve 104 and the oil inlet port of relief valve 102 are both connected to the hydraulic control port of relief valve 102 via throttle valve 105. The oil outlet port of relief valve 102 and the oil return port (port E) of reversing valve 104 are connected to the oil return port (port T) of charging valve 10. The oil outlet port (port D) of reversing valve 104 is connected to either the oil inlet port (port C) or the oil return port (port E). The oil outlet port (port D) of reversing valve 104 is connected to the S signal port of charging valve 10. The S signal port of charging valve 10 is used to output the charging pressure signal.

[0027] When the pressure at the outlet of the charging valve 10 (the pressure within the accumulator 12) is greater than or equal to the opening pressure of the relief valve 102, the relief valve 102 opens, and the hydraulic control end of the reversing valve 104 is connected to the hydraulic oil tank through the relief valve 102. The reversing valve 104 is in the lower position, its oil outlet (port D) is connected to the oil return end (port E), and the pressure output by the S signal port of the charging valve 10 is zero (the pressure within the hydraulic oil tank). When the pressure at the outlet of the charging valve 10 (the pressure within the accumulator 12) is less than the opening pressure of the relief valve 102, the relief valve 102 closes and the reversing valve 104 is in the upper position (the filling position) due to the pressure built up by its hydraulic control end. The oil inlet (port C) of the reversing valve 104 is connected to the oil outlet (port D), and the S signal port of the charging valve 10 outputs the pressure signal of the oil inlet (port P) of the charging valve 10.

[0028] The steering hydraulic system includes a hydraulic oil tank 21, a steering pump 22, a pilot oil supply valve 23, a two-position three-way valve 24, a steering gear 25, a flow amplification valve 26 with a priority valve 261, a steering cylinder 27, an unloading valve 28, and a shuttle valve 29. The steering pump 22 is a gear pump with a fixed displacement function. Its oil intake is connected to the hydraulic oil tank 21, and its pump outlet is connected to the oil inlet of the flow amplification valve 26. The steering cylinder 27 is connected to the flow amplification valve 26, and the flow amplification valve 26 controls the expansion and contraction of the steering cylinder to achieve steering action.

[0029] The oil inlet of the pilot oil supply valve 23 is connected to the pump port of the steering pump 22, and its output is connected to the steering gear 25 and the pilot valve 30 for controlling the distribution valve 32. The output end (port L) and output end (port R) of the steering gear 25 are connected to the hydraulic control end of the main valve in the flow amplification valve 26 to realize the main valve control of the flow amplification valve 26.

[0030] Port CF of flow amplifying valve 26 communicates with the oil inlet of charging valve 10, supplying pressurized charging oil to charging valve 10. Port LS1, the steering load feedback signal port of flow amplifying valve 26, is connected to the second oil inlet of shuttle valve 29. Port EF of flow amplifying valve 26 is connected to the working hydraulic system, supplying pressurized oil thereto.

[0031] The working hydraulic system includes a pilot valve 30, a working pump 31, a distribution valve 32, a boom cylinder 33, a bucket cylinder 34, and an attachment 35. The working pump 31 is a gear pump with a fixed displacement function. Its suction port is connected to the hydraulic oil tank 21, and its pump port is connected to the oil inlet of the distribution valve 32. The boom cylinder 33, bucket cylinder 34, and attachment 35 are connected to and controlled by the distribution valve 32. The hydraulic control port of the distribution valve 32 is connected to the pilot valve 30 and is controlled by the pilot valve 30.

[0032] The EF port of the flow amplification valve 26 is connected to the oil inlet of the unloading valve 28 , the oil outlet of the unloading valve 28 is connected to the oil inlet of the distribution valve 32 , the oil return port of the unloading valve 28 is connected to the oil tank circuit, and the oil tank circuit is connected to the hydraulic oil tank 21 .

[0033] like Figure 1 Figure 2 As shown, the S signal port of the charging valve 10 is connected to the oil inlet (M port) of the two-position three-way valve 24. The oil outlet (O port) of the two-position three-way valve 24 is connected to the first oil inlet port of the shuttle valve 29. The oil return port (N port) of the two-position three-way valve 24 is connected to the tank circuit. The oil outlet (O port) of the two-position three-way valve 24 is connected to the oil return port (N port), or the oil outlet (O port) is connected to the oil inlet (M port). The oil outlet of the shuttle valve 29 is connected to the control signal port (LS port) of the priority valve 261 in the flow amplifier valve 26.

[0034] The two-position three-way valve 24 can be a hydraulically controlled valve, such as Figure 1 Figure 2 As shown, its hydraulic control end is connected to the oil inlet of the flow amplification valve 26. When the pressure of its hydraulic control end does not reach the predetermined value, it is in normal state, and its oil return port (N port) is connected to the oil outlet end (O port); when the pressure of its hydraulic control end is greater than the predetermined value, it is in the lower position, and its oil inlet (M port) is connected to the oil outlet end (O port).

[0035] The two-position three-way valve 24 may be a solenoid valve, such as Figure 3 As shown, when it is powered off, it is in normal state, and its oil inlet (M port) is connected to the oil outlet (O port); when it is powered on, it is in the lower position, and its oil return port (N port) is connected to the oil outlet (O port).

[0036] In this embodiment, after the engine has been shut down for an extended period, the pressure in the accumulator 12 of the brake hydraulic system drops due to valve leakage. When the pressure in the accumulator 12 drops to the set filling pressure, the relief valve 102 in the filling valve 10 closes, and the reversing valve 104 is in the reversing position (up). The oil inlet (port C) and the oil outlet (port D) of the reversing valve 104 are connected. The two-position three-way valve 24 is in the normal position (up), and its oil outlet (port O) is connected to the oil return port (port N). At this point, the engine is started, driven by the starter motor, and the engine drives the steering pump 22. The pressure oil output from the steering pump 22 is delivered to the inlet of the priority valve 261.

[0037] As the steering pump 22 begins to deliver pressurized oil from a stationary start, the pressure at its pump port gradually increases. When the pressure at the hydraulic control port of the two-position, three-way valve 24 (equivalent to the pump port pressure) balances the spring force of its spring chamber, the reversing valve is in the down position, connecting its oil inlet (port M) to its oil outlet (port O). The charging pressure signal from the S signal port of the charging valve 10 flows through the two-position, three-way valve 24 and the shuttle valve 29, acting on the control signal port (port LS) of the priority valve 261, shifting the priority valve 261 to the right position and supplying oil to the charging valve 10. During the period from when the steering pump 22 starts following the engine's stationary start until the pressure at the hydraulic control port of the two-position, three-way valve 24 reaches the pressure required for reversal, the charging pressure signal from the charging valve 10 is not transmitted to the control signal port (port LS) of the priority valve 261. Consequently, the priority valve 261 provides no charging flow to the charging valve 10, effectively enabling engine starting without a charging load, thus facilitating engine starting.

[0038] If the two-position, three-way valve 24 is a solenoid valve, it is energized during engine startup, connecting its return port (port N) to its outlet port (port O). This connects the control signal port LS of the priority valve 261 to the tank circuit. Priority valve 261 is in the left position, and the pressurized oil entering the inlet of priority valve 261 primarily flows out through port EF, passing through the unloading valve to the working hydraulic system for unloading. Only a small amount of pressurized oil is output from port CF of priority valve 261. Therefore, during engine startup, the brake hydraulic system does not charge due to the low pressure in the accumulator 12. The fact that the accumulator 12 is not charged during engine startup does not increase the load on the engine, thereby preventing any increase in engine starting difficulty. When the engine is started, the engine burns fuel to perform external work, and its output torque increases greatly. At this time, the two-position three-way valve 24 is de-energized, and the oil inlet (M port) and the oil outlet (O port) of the two-position three-way valve 24 are connected. The pressure oil at the CF port of the flow amplification valve 26 is transmitted to the control signal port (LS port) of the flow amplification valve 26 through the oil inlet of the charging valve 10, the reversing valve 104, the S signal port of the charging valve 10, the two-position three-way valve 24, and the shuttle valve 29. The priority valve 261 is in the right position. The pressure oil flowing into the oil inlet of the priority valve 261 is mainly output from its CF port and charges the accumulator 12 through the charging valve 10.

[0039] In this embodiment, when the engine is started, the pressure signal transmission from the filling valve 10 to the control signal port (LS port) of the priority valve 261 can be cut off by the two-position three-way valve 24, thereby avoiding filling the filling valve 10 with liquid when the engine is started and increasing the engine starting load, thereby facilitating engine starting.

[0040] In this embodiment, the shuttle valve 29 is arranged after the two-position three-way valve 24. When the two-position three-way valve 24 is stuck, only the filling pressure signal of the filling valve 10 cannot be fed back to the priority valve 261, and the steering load signal (signal of the LS1 port) of the flow amplification valve 26 can still be normally transmitted to the control signal port (LS port) of the priority valve 261, thereby ensuring normal steering.

Claims

1. A loader hydraulic system comprising a brake hydraulic system with a charging valve, a steering hydraulic system with a flow amplification valve, and a working hydraulic system with a distribution valve, wherein the oil inlet of the charging valve is connected to the CF port of the priority valve in the flow amplification valve; and the EF port of the priority valve is connected to the oil inlet of the distribution valve, characterized in that: The loader hydraulic system also includes a two-position three-way valve and a shuttle valve. The oil inlet, oil outlet and oil return port of the two-position three-way valve correspond to the S signal port of the charging valve for outputting the charging pressure signal, the first oil inlet end of the shuttle valve and the oil tank circuit are connected. The oil outlet of the two-position three-way valve is selectively connected to the oil inlet or the oil return port. The LS1 signal port of the flow amplification valve for outputting the steering load feedback pressure is connected to the second oil inlet end of the shuttle valve, and the oil outlet end of the shuttle valve is connected to the control signal port of the priority valve.

2. The loader hydraulic system according to claim 1, characterized in that: The two-position three-way valve is a solenoid valve, and its normal state when it is powered off is that its oil inlet and oil outlet are connected.

3. The loader hydraulic system according to claim 1, characterized in that: The two-position three-way valve is a hydraulically controlled valve, the hydraulically controlled end of which is connected to the oil inlet of the flow amplifying valve, and the normal state is that the oil return port and the oil outlet are connected.

4. The loader hydraulic system according to any one of claims 1 to 3, characterized in that: The charging valve includes a relief valve, a reversing valve, a one-way valve and a throttle valve; the oil inlet of the charging valve is connected to the oil inlet end of the one-way valve and the oil inlet end of the reversing valve at the same time, and the oil outlet of the charging valve is connected to the oil outlet end of the one-way valve and the hydraulic control end of the relief valve at the same time. The hydraulic control end of the reversing valve and the oil inlet end of the relief valve are both connected to the oil outlet end of the one-way valve through the throttle valve; the oil outlet end of the relief valve and the oil return end of the reversing valve are both connected to the oil return port of the charging valve; the oil outlet end of the reversing valve is connected to the S signal port; the oil outlet end of the reversing valve is selectively connected to the oil inlet end or the oil return end.

5. The loader hydraulic system according to claim 4, characterized in that: An unloading valve is connected between the EF port of the priority valve and the oil tank circuit.

6. The loader hydraulic system according to claim 4, characterized in that: The filling valve also includes a second throttle valve, the oil inlet of the filling valve is connected to the oil inlet end of the second throttle valve, and the oil outlet end of the second throttle valve is connected to the oil inlet end of the one-way valve and the oil inlet end of the reversing valve at the same time.

7. The loader hydraulic system according to claim 1, characterized in that: The hydraulic pump connected to the oil inlet of the flow amplification valve in the steering hydraulic system is a gear pump.

8. The loader hydraulic system according to claim 1, characterized in that: The hydraulic pump in the working hydraulic system connected to the oil inlet of the distribution valve is a gear pump.

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

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