A travel throttle brake valve for wheeled hydraulic excavator

Abstract

The present invention discloses a travel throttle brake valve for a wheeled hydraulic excavator, comprising an oil circuit connecting an inlet and an outlet, wherein the oil circuit is divided into two parallel main oil circuits and overflow oil circuits in the valve body, a main throttle valve is installed in the main oil circuit, and an overflow valve is installed in the overflow oil circuit, and the flow of the main oil circuit is controlled by the main throttle valve, and when the inlet oil pressure reaches a certain threshold value, the overflow valve opens the overflow oil circuit under the action of the oil pressure. The application of this brake valve converts the potential energy of the vehicle from the top to the bottom of the slope when going downhill into heat energy by the travel motor, and the heat is brought to the radiator through the hydraulic oil. After the potential energy of the vehicle is converted into heat energy and carried away by the hydraulic oil, it is avoided that the brake drum temperature is too high due to long-term operation of the service brake, and the problem of brake failure caused by serious heating of the brake drum due to long-term operation is solved.

Description

Technical Field

[0001] The prominent problem of brake failure due to heating when the wheeled hydraulic excavator goes down a long slope: the hydraulic system cannot participate in braking when going down a long slope (equivalent to driving a car in neutral gear when sliding downhill), and the only way to control the speed is to rely on drum brakes, wind resistance and rolling resistance. When the slope is large and the slope is long, in order to control the speed within a controllable range, it is inevitable to operate the driving brake for a long time to reduce the speed. Under the action of the braking force, the friction between the shoe and the brake drum causes the temperature of the brake drum to continue to rise. As the temperature of the brake drum rises, the braking efficiency gradually decreases, and in severe cases, it fails, affecting the safety of life and property. Background Art

[0002] The prominent problem of brake failure due to heating when the wheeled hydraulic excavator goes down a long slope: the hydraulic system cannot participate in braking when going down a long slope (equivalent to driving a car in neutral gear when sliding downhill), and the only way to control the speed is to rely on drum brakes, wind resistance and rolling resistance. When the slope is large and the slope is long, in order to control the speed within a controllable range, it is inevitable to operate the driving brake for a long time to reduce the speed. Under the action of the braking force, the friction between the shoe and the brake drum causes the temperature of the brake drum to continue to rise. As the temperature of the brake drum rises, the braking efficiency gradually decreases, and in severe cases, it fails, affecting the safety of life and property. Summary of the invention

[0003] The technical problem to be solved by the present invention is: aiming at the problem of overheating failure of drum brakes of wheeled hydraulic excavators when going down long slopes, a travel throttle brake valve for wheeled hydraulic excavators is designed.

[0004] The technical solution of the present invention is:

[0005] A travel throttle brake valve for a wheeled hydraulic excavator comprises an oil circuit connecting an inlet and an outlet, and is characterized in that the oil circuit is divided into two parallel main oil circuits and an overflow oil circuit in a valve body, a main throttle valve is installed in the main oil circuit, and an overflow valve is installed in the overflow oil circuit, the flow of the main oil circuit is controlled by the main throttle valve, and when the inlet oil pressure reaches a certain threshold value, the overflow valve opens the overflow oil circuit under the action of the oil pressure.

[0006] The movement of the main throttle valve is controlled by the throttle check valve. The control oil pressure is input from the throttle check valve to push the valve core of the main throttle valve.

[0007] One end of the valve core of the main throttle valve is installed by a return spring. When there is no oil pressure input to the throttling check valve, the return spring pushes the valve core of the main throttle valve back.

[0008] The main oil circuit is composed of an inlet section, an outlet section and a throttling section. An oil replenishment circuit is set to connect the outlet and inlet sections of the main oil circuit, and a one-way valve is installed to ensure that the oil can only flow from the outlet section of the main oil circuit to the inlet section.

[0009] The valve core of the main throttle valve is installed in the throttling section, which is composed of an inlet chamber, a throttling chamber and an outlet chamber. The inlet chamber is connected to the inlet section, the outlet chamber is connected to the outlet section, the throttling chamber connects the inlet chamber and the outlet chamber, and the throttling chamber is closed when the valve core of the main throttle valve is closed; the overflow oil circuit connects the outlet chamber and the inlet section, and the oil supply circuit connects the inlet chamber and the outlet section.

[0010] The valve core of the main throttle valve is in the shape of a stepped shaft. Two rods connect the sealing plug in the middle and the sealing pistons at both ends. The sealing pistons at both ends are installed in the mounting holes of the valve body and sealed with end covers. A return spring is installed in one end cover and a throttling check valve is installed on the other end cover.

[0011] The return spring is sleeved on the limit screw, and the maximum stroke of the valve core is adjusted by the limit screw. A throttling groove is opened on the sealing plug in the middle of the valve core.

[0012] This throttle brake valve is installed on the oil outlet circuit of the motor and closes the main throttle valve during braking.

[0013] Beneficial effects of the present invention:

[0014] The application of the brake valve converts the potential energy of the vehicle from the top to the bottom of the slope when going downhill into heat energy through the travel motor, and carries the heat to the radiator through the hydraulic oil. After the vehicle's potential energy is converted into heat energy and carried away by the hydraulic oil, it avoids the long-term operation of the service brake causing the brake drum to overheat, and solves the problem of brake failure caused by the long-term operation of the brake drum due to severe heating. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the schematic diagram of the throttle brake valve in the walking state.

[0016] Figure 2 This is the schematic diagram of the throttle brake valve under braking state.

[0017] Figure 3 Schematic diagram of the throttle brake valve structure.

[0018] Figure 4 It is a structural schematic diagram of the throttle brake valve in the throttling state. DETAILED DESCRIPTION

[0019] Embodiment 1:

[0020] The throttle brake valve of this embodiment includes two parallel oil circuits, a main oil circuit and an overflow oil circuit. The inlet and outlet of the main oil circuit and the overflow oil circuit are the same. A main throttle valve is installed in the main oil circuit, and an overflow valve is installed in the overflow oil circuit. The flow of the main oil circuit is controlled by moving the valve core of the main throttle valve. After throttling starts, the oil pressure at the inlet increases rapidly. When the inlet oil pressure reaches a certain threshold value, the overflow valve opens the overflow oil circuit under the action of the oil pressure, and the oil pressure difference between the inlet and the outlet is controlled within a certain range.

[0021] Furthermore, the left end of the valve core of the main throttle valve is connected to the return spring, and the right end is installed in the control oil chamber. Under normal conditions, the valve core is pushed open by the return spring and does not affect the circulation of the main oil circuit. When the control oil pressure enters the control oil chamber through the throttling check valve, the valve core of the main throttle valve is pushed to limit the cross-section of the main flow path and control the flow rate. After the control oil pressure is lost, the valve core returns to its original position under the action of the return spring.

[0022] Example 2: Figure 1 This is a working principle diagram of the throttle brake valve of this embodiment under normal driving conditions. The throttle brake valve includes two parallel oil circuits, a main oil circuit and an overflow oil circuit. The inlet and outlet of the main oil circuit and the overflow oil circuit are the same. A main throttle valve is installed in the main oil circuit, and an overflow valve is installed in the overflow oil circuit. The flow of the main oil circuit is controlled by moving the valve core of the main throttle valve. After throttling starts, the oil pressure at the inlet increases rapidly. When the inlet oil pressure reaches a certain threshold value, the overflow valve opens the overflow oil circuit under the action of the oil pressure, and the oil pressure difference between the inlet and the outlet is controlled within a certain range.

[0023] The left end of the valve core of the main throttle valve is connected to the return spring, and the right end is installed in the control oil chamber. Under normal conditions, the valve core is pushed open by the return spring, which does not affect the circulation of the main oil circuit. When the control oil pressure enters the control oil chamber through the throttling check valve, the valve core of the main throttle valve is pushed to the closed state to limit the cross-section of the main flow path and control the flow; after losing the control oil pressure, the valve core returns to its original position under the action of the return spring. In the closed state, the main flow path is not completely closed immediately. A throttling groove is provided on the valve core. The throttling groove and the inner wall of the throttling chamber of the main flow path form a throttling channel after cooperation. As the control oil pressure increases, the more the valve core moves to the left, the smaller the cross-sectional area of ​​the throttling channel. Install the throttling brake valve on the oil outlet circuit of the motor, and connect the throttling check valve and the control oil circuit.

[0024] Set up an oil replenishment line connecting the outlet and inlet sections of the main oil circuit, and install a one-way valve so that the oil can only flow from the outlet section of the main oil circuit to the inlet section. If the oil replenishment line and the one-way valve are not set up, if the foot suddenly releases the pedal when reversing, the valve core is in the closed state, and the vehicle drags the motor to rotate, which will cause serious air suction.

[0025] like Figure 2 This is the working principle diagram of the throttle brake valve under throttling state, such as Figure 2As shown, when the wheeled hydraulic excavator needs to decelerate from the normal driving state, first slowly release the travel speed control pedal. When the travel speed control pedal is slowly released, the k port of the throttle brake valve will be connected to the pilot control pressure oil in the accumulator. The control pressure oil slowly pushes the throttle valve core to move left and to the right position through the throttle hole of the throttle brake valve. When the vehicle is in the forward state, the return oil channel of the motor cannot smoothly flow through the P2 port back to the oil tank due to the throttling of the throttle valve core. Under the throttling action of the throttle valve core, the pressure at the motor oil outlet increases rapidly, and the pressure oil at the motor outlet provides a reverse braking torque to the motor, forcing the vehicle to decelerate. When the motor outlet pressure (P1 port pressure) rises to the pressure set by the relief valve, the relief valve overflows and releases the pressure. At the same time, the motor pressure oil also passes through the throttle channel of the throttle valve core to make the oil hot. When the slope slows down or the vehicle speed drops to a certain speed, the pressure at the motor outlet drops below the relief valve set pressure, the relief valve closes, and the oil at the motor oil outlet only passes through the throttle channel of the throttle valve core, and the vehicle's deceleration gradually decreases. When the vehicle speed drops to the driver's target value and the travel pedal is stepped on, the control pressure oil that controls the movement of the throttle valve core returns to the fuel tank through the one-way valve, and the throttle valve core moves right under the action of the return spring to return the valve core to the left position to work, and the throttle brake valve returns to the default non-throttling condition.

[0026] Example 3: Figure 3 A check valve 10, a relief valve 7, a main throttle valve 8 and a throttling check valve 12 are installed in the valve body 9 of the throttling brake valve. There are 4 oil circuits: a main oil circuit, an overflow oil circuit, an oil supply circuit and a control oil circuit. The main oil circuit consists of an inlet section, an outlet section and a throttling section. The throttling section consists of an inlet chamber, a throttling chamber and an outlet chamber. The inlet chamber is connected to the inlet section, the outlet chamber is connected to the outlet section, the throttling chamber connects the inlet chamber and the outlet chamber, and the throttling chamber is closed when the valve core of the main throttle valve 8 is closed; the overflow oil circuit connects the outlet chamber and the inlet section, and the relief valve 7 is installed; the oil supply circuit connects the inlet chamber and the outlet section, and the check valve 10 is installed.

[0027] The valve core of the main throttle valve 8 is in the shape of a stepped shaft. Two rods connect the sealing plug in the middle and the sealing pistons at both ends. The sealing pistons at both ends are installed in the mounting holes of the valve body 9 and sealed with an end cover 6 and a second end cover 11. A return spring 5, a spring seat 4 and a limit screw 3 are installed in the end cover 6, and a throttling check valve 12 is installed on the second end cover 11. The position of the main throttle valve 8 can be adjusted by rotating the limit screw 3 through the locking nut 2, and the position of the main throttle valve 8 affects the flow rate when the valve is closed.

[0028] Install the throttle brake valve on the oil output circuit of the motor, and connect the throttle check valve 12 and the pilot control pressure oil. During normal driving, there is no pilot control pressure oil input, the main throttle valve 8 is in the open valve state under the action of the return spring 5, and the motor oil flows directly from the main oil circuit. When the wheeled hydraulic excavator needs to slow down from the normal driving state, first slowly release the travel speed control pedal, the pilot control pressure oil in the accumulator connects the throttle check valve 12 to enter the control oil circuit, and pushes the valve core of the main throttle valve 8 to the left, achieving Figure 4 The state shown. A throttling groove is provided on the sealing plug in the middle of the valve core. After the throttling groove enters the throttling cavity, it cooperates with the inner wall surface to form a throttling channel. As the valve core moves to the left, the throttling channel becomes smaller and smaller. In the throttling state, the oil pressure at the inlet section increases rapidly, and the pressure oil at the motor outlet provides a reverse braking torque to the motor, forcing the vehicle to slow down. When the oil pressure increases to the preset threshold value of the relief valve 7, the relief valve 7 opens, and the pressure oil enters the outlet section from the overflow oil circuit.

[0029] If the foot is suddenly released during reversing, the valve core of the main throttle valve 8 is in a closed state, the vehicle drags the motor to rotate, the oil pressure at the inlet section decreases, and the one-way valve 10 opens to replenish oil to the motor through the oil replenishment line.

Claims

1. A travel throttle brake valve for a wheeled hydraulic excavator, comprising an oil circuit connecting an inlet and an outlet, characterized in that: The oil circuit is divided into two parallel main oil circuits and overflow oil circuits in the valve body. A main throttle valve is installed in the main oil circuit, and an overflow valve is installed in the overflow oil circuit. The flow of the main oil circuit is controlled by the main throttle valve. When the inlet oil pressure reaches a certain threshold value, the overflow valve opens the overflow oil circuit under the action of oil pressure. The main oil circuit consists of an inlet section, an outlet section and a throttling section. An oil replenishment circuit connecting the inlet and outlet sections of the main oil circuit is provided, and a one-way valve is installed so that the oil can only flow from the outlet section of the main oil circuit to the inlet section. The valve core of the main throttle valve is installed in the throttling section. The throttling section consists of an inlet chamber, a throttling chamber and an outlet chamber. The inlet chamber is connected to the inlet section, and the outlet chamber is connected to the outlet section. The throttling chamber connects the inlet chamber and the outlet chamber. The throttling chamber is closed when the valve core of the main throttle valve is closed. The overflow oil circuit connects the outlet chamber and the inlet section, and the oil replenishment circuit connects the inlet chamber and the outlet section.

2. The wheeled hydraulic excavator travel throttle brake valve according to claim 1, characterized in that: The movement of the main throttle valve is controlled by the throttle check valve. The control oil pressure is input from the throttle check valve to push the valve core of the main throttle valve.

3. The travel throttle brake valve for a wheeled hydraulic excavator according to claim 2, characterized in that: One end of the valve core of the main throttle valve is installed by a return spring. When there is no oil pressure input to the throttling check valve, the return spring pushes the valve core of the main throttle valve back.

4. The wheeled hydraulic excavator travel throttle brake valve according to claim 3, characterized in that: The valve core of the main throttle valve is in the shape of a stepped shaft. Two rods connect the sealing plug in the middle and the sealing pistons at both ends. The sealing pistons at both ends are installed in the mounting holes of the valve body and sealed with end covers. A return spring is installed in one end cover and a throttling check valve is installed on the other end cover.

5. The travel throttle brake valve for a wheeled hydraulic excavator according to claim 4, characterized in that: The return spring is sleeved on the limit screw, and the maximum stroke of the valve core is adjusted by the limit screw. A throttling groove is opened on the sealing plug in the middle of the valve core.

6. The travel throttle brake valve for a wheeled hydraulic excavator according to claim 3 or 4, characterized in that: The throttle brake valve is installed on the oil outlet circuit of the motor to close the main throttle valve during braking.

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