JPS635978Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a pneumatic circuit for a wheeled hydraulic excavator that is equipped with a work brake/service brake device, a parking brake device, and a suspension lock device that are controlled by pneumatic pressure.

FIG. 1 shows an example of a hydraulic excavator, in which an upper rotating body 1 is mounted on the upper part of a lower traveling body 3 equipped with wheels 4.
is mounted so that it can rotate freely. A working device 2 is supported at the front of the revolving upper structure 1 .

Braking for wheel-type hydraulic excavators includes service braking, which decelerates or stops the vehicle while it is running;
There are work brakes that prevent the vehicle body from moving during work, and parking brakes that prevent the vehicle body from moving during parking. Additionally, wheel-type hydraulic excavators have a suspension lock operation to increase the stability of the vehicle body during work and when traveling with a suspended load.

Next, the pneumatic circuit of a conventional wheel-type hydraulic excavator will be explained with reference to FIG.

The discharge side of the compressor 5 driven by the engine is connected to a pressure tank 6, and the pressure tank 6 is connected via an air supply pipe 7 to a service brake valve 8, which is switched by a foot pedal 9, and a work brake valve, which is switched by a lever 11. 10, a parking brake valve 12 which is switched by a lever 13, and a suspension control valve 14 which is switched by a lever 15.

The output ports of the service brake valve 8 and the work brake valve 10 are connected to a shuttle valve 16, and a pressure outlet pipe 17 of the shuttle valve 16 is connected to a booster 18 that converts air pressure into hydraulic pressure and increases the pressure. The booster 18 is connected to a control section of a work brake/service brake device 20 via a hydraulic pipe 19. The brake device 20 is for braking the wheels 4, and when hydraulic pressure from the booster 18 acts on the control section, the brake shoe is expanded against the spring to apply braking to the brake drum. This is a positive brake device that is configured to release the brake when the hydraulic pressure is removed.

The output port of the parking brake valve 12 is connected to the parking brake device 22 via the air guide pipe 21.
The controller is connected to the controller. The parking brake device 22 is installed on a propulsion shaft or the like, and when pressure is supplied to the control section, the brake shoe is contracted against the brake spring to release the brake, and when the pressure from the control section is discharged, the brake spring is released. This is a negative brake device that is configured to perform braking. The output port of the suspension control valve 14 is connected via an air guide pipe 23 to a control section of a suspension lock valve 24 which includes a plurality of check valves. It is connected to a suspension lock cylinder 26, and its input port is connected to an oil tank 28 via a hydraulic pipe 27. One end of the suspension lock cylinder 26 is connected to the undercarriage 3, and the other end is connected to an axle on which wheels 4 are rotatably mounted. When pressure is supplied to the control section of the suspension lock valve 24, this valve 24 is switched from the illustrated position a to the b position, and the suspension lock cylinder 2
The oil in step 6 can freely flow out and in, and the axle can swing. When the pressure in the control section is discharged, the valve 24 is switched to position a, and the check valve prevents oil from flowing out of the suspension lock cylinder 26, so that the axle is fixed.

When the foot pedal 9 is depressed to switch the service brake valve 8 from the illustrated position a to the b position, pressure is sent to the booster 18 via the shuttle valve 16 and the pressure outlet pipe 17, and hydraulic pressure is applied to the control section of the brake device 20. The wheels 4 are then braked. When the working brake valve 10 is switched from the illustrated position a to the b position using the lever 11, hydraulic pressure similarly acts on the control section of the brake device 20, and the wheel 4
braking is performed.

Parking brake valve 1 is activated by lever 13.
2 is switched from the illustrated position a to the b position, pressure air is supplied to the control section of the parking brake device 22, and the braking of the parking brake device 22 is released. Furthermore, when the suspension control valve 14 is switched from the illustrated position a to the b position using the lever 15, pressure is released from the suspension lock valve 24.
The suspension lock is released.

The conventional wheel-type hydraulic excavator described above has the following drawbacks.

(1) When self-propulsion and work are repeated, the number of operations increases, which is troublesome and time-consuming.

(2) Even if the work brake and service brake device is applied during work, the air pressure may drop and the vehicle body may move.

(3) When parking the vehicle for a long time, if the work brake and service brake system is left on, air pressure and hydraulic pressure will continue to be applied to the brake system, shortening the life of seals, seals, etc. There is a risk of air leakage and oil leakage. Furthermore, when the temperature drops, such as at night, water vapor in the compressed air condenses into water, leading to freezing problems and rusting of air equipment and piping.

(4) There is a risk that the vehicle may forget to apply the parking brake when parking, causing the vehicle to run away.

The purpose of this invention is to provide a pneumatic circuit for a wheeled hydraulic excavator that is easy to operate, prevents the car body from running away, and extends the life of seals, packing, etc.

The pneumatic circuit of this invention is used in a wheel-type hydraulic excavator equipped with a work brake/service brake device, a parking brake device, and a suspension lock device controlled by pneumatic pressure, and a service brake valve that is switched by a foot pedal and a solenoid-type work brake. Connect the input ports of the valve, solenoid-type parking brake valve, and solenoid-type suspension control valve to a pressure source, and connect the output ports of the service brake valve and work brake valve to the control section of the work brake and service brake device. , connect the output port of the parking brake valve to the control part of the parking brake device, connect the output port of the suspension control valve to the control part of the suspension locking device, and in its neutral position, the working brake valve solenoid, the parking brake valve One switching position connects the working brake valve solenoid to the power supply, and the other switching position connects the parking brake valve solenoid and the suspension control valve solenoid to the power supply. A changeover switch is provided to connect the solenoid of the valve to the power source, and the changeover switch is connected to the main switch, and braking of the work brake and service brake device is performed by switching the work brake valve by energizing the solenoid.
The braking of the parking brake device is released by switching the parking brake valve by energizing the solenoid, and the locking of the suspension lock device is released by switching the suspension control valve by energizing the solenoid.

An embodiment of this invention will be described below with reference to FIG. In this figure, the same components as in FIG. 2 are represented by the same reference numerals.

The solenoid 29a of the solenoid-type working brake valve 29 is connected to one output terminal 33b of the changeover switch 33 by an electric circuit 32.
The solenoid 30a of the solenoid type parking brake valve 30 is connected to the other output terminal 33c of the changeover switch 33 by an electric circuit 34, and the solenoid type parking brake valve 30 is connected to the other output terminal 33c of the changeover switch 33.
The first solenoid 31a is connected to the output terminal 33c of the changeover switch 33 via an electric circuit 36 into which a switch 35 is inserted. The input terminal 33a of the changeover switch 33 is connected to the main switch 38 by an electric circuit 37.
is connected to a storage battery 39 as a power source. The main switch 38 is closed when the engine key is turned on, and opened when the engine key is turned off. The changeover switch 33 can be manually switched to three positions. That is, in the neutral position shown in the figure, the circuit is open, and when switched to the right side, the electric circuit 37 and the electric circuit 32 are connected via the output terminal 33b, and when switched to the left side, the electric circuit 37 and the electric circuit 32 are connected via the output terminal 33c. 37 is connected to the electric circuit 34 and the electric circuit 36. The rest of the structure is the same as the conventional one shown in FIG.

When the engine key is turned on, the main switch 38 is closed. At this time, if the changeover switch 33 is in the neutral position, which solenoid valve 29, 30,
No current flows to 31, and each solenoid valve 2
9, 30, and 31 are at the a position shown in the figure. That is, the braking of the work brake/service brake device 20 is released, the parking brake device 22 is applied, and the suspension lock cylinder 2 is released.
6 is locked.

When the changeover switch 33 is switched to the right side during work, the current flows through the electric circuit 37, the changeover switch 33, and the electric circuit 32, and the solenoid 29a is energized. As a result, the work brake valve 29 is switched from the a position to the b position, pressure is supplied to the booster 18, and the work brake/service brake device 20 applies braking as described above.

When the selector switch 33 is switched to the left side during driving, current flows through the electric circuit 37, the selector switch 33, and the electric circuit 34, the solenoid 30a is energized, and the parking brake valve 30 is switched from the a position to the b position. As a result, pressure air is supplied to the control section of the parking brake device 22, and the braking of the brake device 22 is released. At the same time, the solenoid 29a is demagnetized, the working brake valve 29 is switched to position a by the force of the spring,
The pressure of the booster 18 is released to the atmosphere, and the work brake/service brake device 20 is braked (the wheels 4
(braking) is also released. Also, the current is electric circuit 3
6, the solenoid 31a is energized via the switch 35, and the suspension control valve 31 is energized via the switch 35.
is switched from position a to position b, pressure air is supplied to the control section of the suspension lock valve 24 through the air guide pipe 23, and the suspension lock cylinder 26 is unlocked and becomes free.

In the case of traveling with a suspended load, etc., when traveling with the suspension lock cylinder 26 locked, opening the switch 35 will not energize the solenoid 31a and the purpose will be achieved.

When the changeover switch 33 is set to the neutral position during parking, the solenoid 30a is demagnetized and the parking brake valve 30 is switched to the a position, and the solenoid 31a is demagnetized and the suspension control valve 31 is switched to the a position. That is, the parking brake device 22 is braked, and the suspension lock cylinder 26 is
is locked.

When the engine key is turned off, the main switch 38 is opened, so regardless of the position of the changeover switch 33, which solenoid 29a, 30
No current flows through a, 31a either, and each solenoid valve 29, 30, 31 is at the a position shown in the figure. That is, the braking of the work brake/service brake device 20 is released, the parking brake device 22 is applied, and the suspension lock cylinder 2 is released.
6 is locked.

According to this invention explained above, the following effects can be obtained.

(1) Operation is easy because the work brake valve, parking brake valve, and suspension control valve can be operated with a single changeover switch.

(2) When the work brake/service brake device is applied, the parking brake device, which is braked by a spring, is always applied.
There is no risk of the car body escaping even if the air pressure drops during work.

(3) When the main switch is opened with the engine key, the brake is automatically released even if the work brake/service brake device is still applied, extending the life of seals, packing, etc., and preventing air leaks. and oil leakage can be prevented. Additionally, condensation of moisture in the compressed air is eliminated, preventing freezing and rust.

(4) When the main switch is opened with the engine key, even if you forget to apply the parking brake device, the brake will be applied automatically, so there is no risk of the vehicle running away.

[Brief explanation of the drawing]

Figure 1 is a side view showing an example of a wheel-type hydraulic excavator, Figure 2 is a diagram showing a pneumatic circuit of a conventional wheel-type hydraulic excavator, and Figure 3 is a diagram showing an embodiment of the pneumatic circuit of this invention. It is. 5... Compressor, 6... Pressure tank, 7... Air supply pipe, 8... Service brake valve, 9... Foot pedal, 16... Shuttle valve, 17... Pressure takeoff pipe, 18... Booster, 19 ...hydraulic piping,
20...Work brake and service brake device,
21... Air guide pipe, 22... Parking brake device, 23... Air guide pipe, 24... Suspension lock valve, 25... Hydraulic piping, 26... Suspension lock cylinder, 27... Hydraulic piping, 2
8...Oil tank, 29...Solenoid type working brake valve, 29a...Solenoid, 30...
Solenoid type parking brake valve, 30
a... Solenoid, 31... Solenoid type suspension control valve, 31a... Solenoid,
32... Electric circuit, 33... Selector switch, 34
...Electric circuit, 35...Switch, 36...Electric circuit, 37...Electric circuit, 38...Main switch, 39...Storage battery.

Claims (1)

[Scope of utility model registration request] A wheel-type hydraulic excavator equipped with a service brake device that also serves as a work brake controlled by pneumatic pressure, a parking brake device, and a suspension lock device, including a service brake valve that is switched by a foot pedal, a solenoid-type work brake valve, and a solenoid-type parking brake valve. Connect the input ports of the and solenoid-type suspension control valve to a pressure source, connect the output ports of the service brake valve and work brake valve to the control section of the work brake and service brake device, and connect the output ports of the parking brake valve to the control section of the work brake and service brake device. Connect to the control section of the parking brake device, connect the output port of the suspension control valve to the control section of the suspension lock device,
In the neutral position, the working brake valve solenoid, the parking brake valve solenoid, and the suspension control valve solenoid are all disconnected from the power source, and in one switching position, the working brake valve solenoid is connected to the power source, and the other side is connected to the working brake valve solenoid. At the switching position, a changeover switch is provided that connects the parking brake valve solenoid and the suspension control valve solenoid to the power source, and the changeover switch is connected to the main switch, and the working brake valve is switched by energizing the solenoid. The work brake/service brake device is braked, the parking brake device is released by switching the parking brake valve by energizing the solenoid, and the locking of the suspension lock device is released by switching the suspension control valve by energizing the solenoid. A pneumatic circuit characterized by being configured as follows.