Bulldozing blade lifting hydraulic system and excavator

Abstract

The utility model relates to a dozer blade of an excavator, and provides a dozer blade lifting hydraulic system and the excavator in order to solve the problem that the dozer blade of the excavator can be paused in the descending process, and in the hydraulic system, a large cavity and a small cavity of a dozer blade oil cylinder are connected with a dozer blade control valve through a hydraulic lock; the hydraulic control end of a large cavity linkage hydraulic control one-way valve in the hydraulic lock is connected with the forward conduction oil inlet end of a small cavity linkage hydraulic control one-way valve; the oil outlet end of the dozer blade descending unlocking device is connected with the hydraulic control end of the small cavity linkage hydraulic control one-way valve, and the dozer blade descending unlocking device is connected with the dozer blade control device and outputs pressure oil for reverse conduction opening of the small cavity linkage hydraulic control one-way valve in response to dozer blade descending operation signals of the dozer blade control device. In the utility model, the small cavity of the dozer blade oil cylinder is linked with the hydraulic control one-way valve and is linked with the dozer blade descending operation of the dozer blade control device, so that the dozer blade can be prevented from pausing in the descending process.

Description

Technical Field

[0001] The utility model relates to a bulldozing blade of an excavator, and more specifically, to a hydraulic system for lifting the bulldozing blade and an excavator. Background Art

[0002] Some excavators are equipped with a bulldozing blade at the front of the lower traveling chassis. The bulldozing blade is driven to lift by a bulldozing blade oil cylinder. The hydraulic system for lifting the bulldozing blade includes a working pump, a bulldozing blade control valve, a bulldozing blade pilot valve and a bulldozing blade oil cylinder connected by pipelines. The working pump, the bulldozing blade control valve and the bulldozing blade pilot valve are arranged on the upper body of the excavator, and the bulldozing blade oil cylinder is arranged on the lower body. The connecting pipeline is connected to the bulldozing blade oil cylinder through a central swivel joint from the upper body.

[0003] In the hydraulic system for lifting the bulldozing blade, the bulldozing blade control valve has a spool valve structure, and there is a clearance fit between its spool and the valve body. Therefore, oil leakage inevitably occurs. When the bulldozing blade control valve is in the neutral position, due to the gravity of the bulldozing blade itself and the oil leakage factor of the bulldozing blade control valve, the bulldozing blade oil cylinder will slowly extend, resulting in the descent of the bulldozing blade oil cylinder. To avoid the slow self-extension of the bulldozing blade oil cylinder, a hydraulic lock is provided on the bulldozing blade oil cylinder. The large chamber and the small chamber of the bulldozing blade oil cylinder are connected to the bulldozing blade control valve through the hydraulic lock. The hydraulic lock is composed of two pilot-operated check valves. As Figure 1 shown, in the hydraulic lock 2, the pilot end of the large chamber-connected pilot-operated check valve 22 is connected to the forward-conducting oil inlet end of the small chamber-connected pilot-operated check valve 21, and the pilot end of the small chamber-connected pilot-operated check valve 21 is connected to the forward-conducting oil inlet end of the large chamber-connected pilot-operated check valve 22. The oil in the small chamber of the bulldozing blade oil cylinder 1 flows out through the small chamber-connected pilot-operated check valve 21, and the pressure at the forward-conducting oil inlet end of the large chamber-connected pilot-operated check valve 22 must be able to open the small chamber-connected pilot-operated check valve 21. Similarly, the oil in the large chamber of the bulldozing blade oil cylinder 1 flows out through the large chamber-connected pilot-operated check valve 22, and the pressure at the forward oil inlet end of the small chamber-connected pilot-operated check valve 21 must be able to open the large chamber-connected pilot-operated check valve 22, so as to lock the bulldozing blade oil cylinder 1 when it is not operated.

[0004] In the above hydraulic system for lifting the bulldozing blade, as Figure 1As shown in the figure, when the bulldozer blade lowering operation is performed, the pressure oil output from the large chamber connection oil port of the bulldozer blade control valve flows to the large chamber of the bulldozer blade cylinder 1. As a result, the small chamber connected pilot check valve 21 is reversely conducted. The oil in the small chamber of the bulldozer blade cylinder 1 flows to the bulldozer blade control valve through the reversely small chamber connected pilot check valve 21, and the bulldozer blade descends. During the process of the bulldozer blade descending, the bulldozer blade cylinder 1 extends. On the one hand, it is due to the oil inlet of the large chamber of the bulldozer blade cylinder 1. On the other hand, it is because the self-weight of the bulldozer blade pulls the bulldozer blade cylinder to cause it to extend. If during the extension process of the bulldozer blade cylinder 1, the oil inlet of the large chamber of the bulldozer blade cylinder 1 cannot adapt to its extension speed, the pressure in the large chamber of the bulldozer blade cylinder 1 will decrease. If the pressure in the large chamber of the bulldozer blade cylinder 1 drops below the reverse conduction opening pressure of the small chamber connected pilot check valve 21, the small chamber connected pilot check valve 21 will close, the oil in the small chamber of the bulldozer blade cylinder 1 cannot flow out, the bulldozer blade cylinder 1 stops extending, the bulldozer blade stops descending, and the bulldozer blade cylinder 1 has to wait until the pressure in its large chamber cylinder reaches the reverse conduction opening of the small chamber connected pilot check valve 21 again before extending. During the above bulldozer blade lowering operation process, the stop of the extension of the bulldozer blade cylinder will produce a sense of jerk. Utility Model Content

[0005] The technical problem to be solved by the present utility model is that there may be a problem of jerk in the bulldozer blade cylinder during the process of the bulldozer blade descending in the existing bulldozer blade lifting hydraulic system, and a bulldozer blade lifting hydraulic system and an excavator are provided.

[0006] The technical solution for the present utility model to achieve its purpose is: a bulldozer blade lifting hydraulic system, including a bulldozer blade cylinder, a bulldozer blade control valve, a bulldozer blade control device for controlling the bulldozer blade control valve. The large chamber and the small chamber of the bulldozer blade cylinder are connected to the bulldozer blade control valve through a hydraulic lock. In addition, a bulldozer blade lowering unlocking device is further included. The hydraulic control end of the large chamber connected pilot check valve in the hydraulic lock is connected to the forward conduction oil inlet end of the small chamber connected pilot check valve; the oil outlet end of the bulldozer blade lowering unlocking device is connected to the hydraulic control end of the small chamber connected pilot check valve. The bulldozer blade lowering unlocking device is connected to the bulldozer blade control device and outputs the pressure oil for the reverse conduction opening of the small chamber connected pilot check valve in response to the bulldozer blade lowering operation signal of the bulldozer blade control device.

[0007] In the lift hydraulic system of the earthmoving blade of the present utility model, the earthmoving blade lowering unlocking device includes a pressure oil source and a normally closed unlocking valve; the oil inlet of the unlocking valve is connected to the pressure oil source, and the oil outlet is connected to the hydraulic control end of the hydraulic control one-way valve of the small chamber. The hydraulic control end for controlling the opening and closing between the oil inlet and the oil outlet of the unlocking valve is communicated with the earthmoving blade lowering hydraulic control end of the earthmoving blade control valve. Alternatively, the earthmoving blade control device includes a controller and an electric control handle electrically connected to the controller for operating the lifting of the earthmoving blade; the earthmoving blade lowering unlocking device includes a pressure oil source and a normally closed unlocking valve; the oil inlet of the unlocking valve is connected to the pressure oil source, and the oil outlet is connected to the hydraulic control end of the hydraulic control one-way valve of the small chamber. The electric control end for controlling the opening and closing between the oil inlet and the oil outlet of the unlocking valve is electrically connected to the controller.

[0008] In the lift hydraulic system of the earthmoving blade of the present utility model, the unlocking valve is a two-way three-way valve with the oil return port communicated with the hydraulic oil tank; the oil outlet of the unlocking valve is selectively communicated with the oil inlet or the oil return port.

[0009] In the lift hydraulic system of the earthmoving blade of the present utility model, the pressure oil source is a pilot pressure oil source.

[0010] In the lift hydraulic system of the earthmoving blade of the present utility model, the earthmoving blade control device includes a hand pilot valve with the oil inlet and outlet respectively connected to the pressure oil source and the hydraulic control end of the earthmoving blade control valve.

[0011] In the lift hydraulic system of the earthmoving blade of the present utility model, the earthmoving blade control device further includes an electro-hydraulic proportional valve with the oil inlet and outlet respectively connected to the pressure oil source and the hydraulic control end of the earthmoving blade control valve. The electro-hydraulic proportional valve is electrically connected to the controller.

[0012] The technical solution for the present utility model to achieve its purpose is: an excavator, which includes the aforementioned lift hydraulic system of the earthmoving blade. The earthmoving blade cylinder is arranged on the lower body, and the earthmoving blade control valve, the earthmoving blade control device, and the earthmoving blade lowering unlocking device are arranged on the upper body; the earthmoving blade lowering unlocking device is connected to the hydraulic control one-way valve of the small chamber arranged on the lower body through pipelines and a central swivel joint. Further, the excavator is a wheeled excavator or a crawler excavator.

[0013] Compared with the prior art, in the present utility model, the hydraulic control one-way valve of the small chamber of the earthmoving blade cylinder is linked with the earthmoving blade lowering operation of the earthmoving blade control device, which can prevent pauses during the lowering process of the earthmoving blade. Description of the Drawings

[0014] Figure 1 It is the working principle diagram of the hydraulic lock of the earthmoving blade cylinder in the prior art.

[0015] Figure 2This is the schematic diagram of the lifting hydraulic system of the bulldozer blade of the present utility model.

[0016] Names and serial numbers of components in the figure:

[0017] Bulldozer blade cylinder 1, hydraulic lock 2, small chamber connected pilot check valve 21, large chamber connected pilot check valve 22, center swivel joint 3, bulldozer blade control valve 4, unlocking valve 5, controller 6, electric control handle 7, hydraulic oil tank 8. Specific implementation manners

[0018] The following describes the specific implementation manners in conjunction with the drawings.

[0019] As Figure 1 shown, the lifting hydraulic system of the bulldozer blade includes a bulldozer blade cylinder 1, a bulldozer blade control valve 4, a bulldozer blade control device for controlling the bulldozer blade control valve 4, and the large chamber and small chamber of the bulldozer blade cylinder 1 are connected to the bulldozer blade control valve 4 through a hydraulic lock 2. The lifting hydraulic system of the bulldozer blade further includes a bulldozer blade lowering unlocking device. The hydraulic control end of the large chamber connected pilot check valve 22 in the hydraulic lock 2 is connected to the forward conduction oil inlet end of the small chamber connected pilot check valve. The oil outlet end of the bulldozer blade lowering unlocking device is connected to the hydraulic control end of the small chamber connected pilot check valve 21. The bulldozer blade lowering unlocking device is connected to the bulldozer blade control device and outputs pressure oil for the reverse conduction and opening of the small chamber connected pilot check valve 21 in response to the bulldozer blade lowering operation signal of the bulldozer blade control device. The bulldozer blade lowering operation signal is an electric signal or a hydraulic signal generated based on the bulldozer blade lowering operation.

[0020] Optionally, the bulldozer blade control device includes a controller 6, an electric control handle 7 electrically connected to the controller 6 for bulldozer blade lifting operation, and an electro-hydraulic proportional valve (not shown in the figure) whose oil inlet and outlet are respectively connected to a pressure oil source (not shown in the figure) and the hydraulic control end of the bulldozer blade control valve 4. The electro-hydraulic proportional valve is electrically connected to the controller 6. The bulldozer blade lowering unlocking device includes a pressure oil source and a normally closed unlocking valve 5. The oil inlet of the unlocking valve 5 is connected to the pressure oil source, the oil outlet is connected to the hydraulic control end of the small chamber connected pilot check valve 21, and the electric control end for controlling the opening and closing between the oil inlet and the oil outlet on the unlocking valve 5 is electrically connected to the controller 6.

[0021] Further, the pressure oil source is a pilot oil source, which can be a pilot pump or a pilot oil supply valve connected to the working pump. The pilot oil supply valve reduces the high-pressure oil of the work into pilot control oil for hydraulic valve control.

[0022] The unlocking valve 5 is a two-position three-way solenoid valve whose oil return port (T port) is communicated with the hydraulic oil tank 8; the oil outlet (A port) of the unlocking valve 5 is selectively communicated with the oil inlet port (P port) or the oil return port (T port).

[0023] When the operator performs the operation of lowering the bulldozer blade, the operator swings the electro-hydraulic control handle 7. The electro-hydraulic control handle 7 sends an electrical signal to the controller 6. The controller 6 outputs a control current to the electro-hydraulic proportional valve. The corresponding electro-hydraulic proportional valve outputs pilot pressure oil to the hydraulic control end of the bulldozer blade control valve 4. The bulldozer blade control valve 4 changes its direction. The pressure oil output from the oil port connected to the large chamber thereof flows through the large-chamber-connected pilot check valve 22 that conducts in the forward direction to the large chamber of the bulldozer blade cylinder 1. When the controller 6 outputs a control current for lowering the bulldozer blade to the electro-hydraulic proportional valve, it outputs a control current to the unlocking valve 5 to make the unlocking valve 5 change its direction. Its oil inlet port (P port) is in communication with the oil outlet port (A port). The pressure oil supplied by the pressure oil source acts on the hydraulic control end of the small-chamber-connected pilot check valve 21 in the hydraulic lock 2 through the unlocking valve 5, making the small-chamber-connected pilot check valve 21 conduct in the reverse direction. The oil in the small chamber of the bulldozer blade cylinder 1 flows back to the hydraulic oil tank 8 through the small-chamber-connected pilot check valve 21 and the bulldozer blade control valve 4. The bulldozer blade cylinder 1 extends, realizing the lowering of the bulldozer blade. During the whole operation process of lowering the bulldozer blade, the unlocking valve 5 outputs pressure oil all the time to make the small-chamber-connected pilot check valve 21 conduct in the reverse direction. The reverse conduction of the small-chamber-connected pilot check valve 21 has nothing to do with the pressure in the large chamber of the bulldozer blade cylinder 1. Therefore, there will be no phenomenon that the extension of the bulldozer blade cylinder stops due to the low pressure in the large chamber of the bulldozer blade cylinder 1, eliminating the possible jerks during the process of lowering the bulldozer blade.

[0024] When the operator performs the operation of lifting the bulldozer blade, the controller 6 controls the bulldozer blade control valve 4 through the corresponding electro-hydraulic proportional valve. The pressure oil output from the oil port connected to the small chamber of the bulldozer blade control valve 4 flows through the small-chamber-connected pilot check valve 21 that conducts in the forward direction to the small chamber of the bulldozer blade cylinder 1. The pressure of the pressure oil output from the oil port connected to the small chamber of the bulldozer blade control valve 4 acts on the hydraulic control end of the large-chamber-connected pilot check valve 22 in the hydraulic lock 2, making the large-chamber-connected pilot check valve 22 conduct in the reverse direction. The oil in the large chamber of the bulldozer blade cylinder 1 flows back to the hydraulic oil tank 8 through the large-chamber-connected pilot check valve 22 and the bulldozer blade control valve 4. The bulldozer blade cylinder 1 retracts, and the bulldozer blade rises.

[0025] When the operator does not perform the operation of lifting or lowering the bulldozer blade, the controller 6 does not output a control current to the unlocking valve 5. The oil inlet port and the oil outlet port of the unlocking valve 5 are cut off. There is no pressure oil acting on the hydraulic control ends of the large-chamber-connected pilot check valve 22 and the small-chamber-connected pilot check valve 21 in the hydraulic lock 2 to make them conduct in the reverse direction. Both the large-chamber-connected pilot check valve 22 and the small-chamber-connected pilot check valve 21 are in the reverse cut-off state. The oil in the large chamber and the small chamber of the bulldozer blade cylinder 1 cannot flow out, realizing the telescopic locking of the bulldozer blade cylinder.

[0026] Optionally, the unlocking valve 5 can also be a hydraulically controlled two-way three-way valve, whose hydraulically controlled end is directly communicated with the hydraulically controlled end of the bulldozer blade lowering of the bulldozer blade control valve 4. When the bulldozer blade lowering operation is performed, the pilot pressure oil acting on the hydraulically controlled end of the bulldozer blade lowering of the bulldozer blade control valve 4 also acts on the hydraulically controlled end of the unlocking valve 5 at the same time, causing it to change from the closed state between the oil inlet and the oil outlet to the conducting state, so that the small chamber associated hydraulic check valve 21 can conduct reversely.

[0027] This embodiment also provides an excavator, which includes the aforementioned bulldozer blade lifting and lowering hydraulic system. The bulldozer blade cylinder is arranged on the lower body, and the bulldozer blade control valve, the bulldozer blade control device, and the bulldozer blade lowering unlocking device are arranged on the upper body; the bulldozer blade lowering unlocking device is connected to the small chamber associated hydraulic check valve arranged on the lower body, such as arranged on the bulldozer blade cylinder, through a pipeline and a central rotary joint. Optionally, the excavator is a wheeled excavator or a crawler excavator.

Claims

1. A lifting hydraulic system for a bulldozer blade, comprising a bulldozer blade cylinder, a bulldozer blade control valve, a bulldozer blade control device for controlling the bulldozer blade control valve, and the large chamber and the small chamber of the bulldozer blade cylinder are connected to the bulldozer blade control valve through a hydraulic lock; characterized in that, It further includes a dozer blade lowering unlocking device. The hydraulic control end of the hydraulic check valve in the large chamber is connected to the forward-conducting oil inlet end of the hydraulic check valve in the small chamber. The oil outlet end of the dozer blade lowering unlocking device is connected to the hydraulic control end of the hydraulic check valve in the small chamber. The dozer blade lowering unlocking device is connected to the dozer blade control device and outputs pressure oil for reverse conduction and opening of the hydraulic check valve in the small chamber in response to the dozer blade lowering operation signal of the dozer blade control device.

2. The lift hydraulic system of the bulldozer blade according to claim 1, characterized in that The dozer blade lowering unlocking device includes a pressure oil source and a normally closed unlocking valve. The oil inlet of the unlocking valve is connected to the pressure oil source, the oil outlet is connected to the hydraulic control end of the hydraulic check valve in the small chamber, and the hydraulic control end for controlling the opening and closing between the oil inlet and the oil outlet of the unlocking valve is communicated with the dozer blade lowering hydraulic control end of the dozer blade control valve.

3. The lift hydraulic system of the bulldozer blade according to claim 1, characterized in that, The dozer blade control device includes a controller and an electric control handle electrically connected to the controller for dozer blade lifting and lowering operations. The dozer blade lowering unlocking device includes a pressure oil source and a normally closed unlocking valve. The oil inlet of the unlocking valve is connected to the pressure oil source, the oil outlet is connected to the hydraulic control end of the hydraulic check valve in the small chamber, and the electric control end for controlling the opening and closing between the oil inlet and the oil outlet of the unlocking valve is electrically connected to the controller.

4. The lift hydraulic system of the bulldozer blade according to claim 2 or 3, characterized in that, The unlocking valve is a two-position three-way valve with the oil return port communicated with the hydraulic oil tank. The oil outlet of the unlocking valve is selectively conducted with the oil inlet or the oil return port.

5. The lift hydraulic system of the bulldozer blade according to claim 2 or 3, characterized in that, The pressure oil source is a pilot pressure oil source.

6. The lift hydraulic system of the bulldozer blade according to claim 2, wherein, The dozer blade control device includes a controller, an electric control handle electrically connected to the controller for dozer blade lifting and lowering operations, and an electro-hydraulic proportional valve with the oil inlet and outlet respectively connected to the pressure oil source and the hydraulic control end of the dozer blade control valve. The electro-hydraulic proportional valve is electrically connected to the controller.

7. The lift hydraulic system of the bulldozer blade according to claim 2, wherein The dozer blade control device includes a hand pilot valve with the oil inlet and outlet respectively connected to the pressure oil source and the hydraulic control end of the dozer blade control valve.

8. The lift hydraulic system of the bulldozer blade according to claim 3, characterized in that, The dozer blade control device further includes an electro-hydraulic proportional valve with the oil inlet and outlet respectively connected to the pressure oil source and the hydraulic control end of the dozer blade control valve. The electro-hydraulic proportional valve is electrically connected to the controller.

9. An excavator, characterized in that, It has the dozer blade lifting and lowering hydraulic system according to any one of claims 1 to 8. The dozer blade cylinder is arranged on the lower body, and the dozer blade control valve, the dozer blade control device, and the dozer blade lowering unlocking device are arranged on the upper body. The dozer blade lowering unlocking device is connected to the hydraulic check valve in the small chamber arranged on the lower body through a pipeline and a central rotary joint.

10. The excavator according to claim 9, characterized in that, The excavator is a wheeled excavator or a crawler excavator.

Images