JP2002067928A - Braking mechanism for mobile construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a braking mechanism for mobile construction machine that does not drag even when outside temperature is low. SOLUTION: This braking mechanism for mobile construction machine comprises a wheel cylinder 21, a booster 22 adapted to intensify a pressure of hydraulic fluid acting on a primary side for transferring it to a brake fluid on a secondary side to drive the wheel cylinder 21, a hydraulic pump 23 and a brake valve to be operated by an operator for being capable of regulating a supplied amount of pressure oil to the booster 22 according to the operating amount to prevent the pressure oil from flowing to the secondary side from the primary side when not operated for exhausting the pressure oil in the secondary side. An exhaust port of the brake valve 25 so as to exhaust the pressure oil in the secondary side is connected with a suction hole side of a hydraulic pump 24 by a connecting circuit 20 for having the hydraulic fluid in the primary side of the booster 22 sucked by the hydraulic pump 23 via the connecting circuit 20 when the brake valve 25 is not operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The invention of this application uses hydraulic oil as a power source for driving a brake device, and uses this hydraulic oil and brake fluid as a medium for transmitting a braking force to the brake device. The present invention relates to a brake mechanism of a self-propelled construction machine such as a wheel shovel called an oil-by-oil brake.

[0002]

2. Description of the Related Art Conventionally, in a brake system of a self-propelled construction machine such as a wheel shovel, compressed air is used as a power source for driving a brake device, and a medium for transmitting a braking force to the brake device. A system called air-over hydrobrake using this compressed air and brake fluid,
A system called an oil-by-oil brake that uses hydraulic oil as the power source and uses the hydraulic oil and brake fluid as a braking force transmission medium to a brake device, and operates on both the power source and the braking force transmission medium. There are three types of brake systems, a system called an all-hydraulic brake using oil.

[0003] The applicant has so far employed a brake system of an air-over hydrobrake as a brake system of a self-propelled construction machine, but this brake system is a dedicated pneumatic device such as a compressor, an air tank, an air dryer and the like. However, there is a problem that the number of parts is large and the cost is disadvantageous. In addition, when air leakage occurs, there is a problem that it takes time to check the location where the air leakage occurs, and that periodic replacement of the pneumatic equipment is required. Accordingly, the applicant has been conducting research and development on using an oil-by-oil brake system instead of such a brake system in a brake system of a self-propelled construction machine.

[0004] The brake mechanism of this oil-by-oil brake self-propelled construction machine increases the hydraulic pressure of hydraulic oil acting on the primary side with a brake device having a wheel cylinder or the like driven by hydraulic pressure of brake fluid. A booster that pressurizes hydraulic fluid in the oil tank to supply hydraulic fluid to the booster, and a hydraulic pump that pressurizes hydraulic oil in the oil tank and supplies the hydraulic fluid to the booster. And a brake valve operated by stepping on the brake pedal. The brake valve is configured to be able to adjust the amount of pressure oil supplied to the booster in accordance with the amount of depression of the brake pedal and to discharge the secondary side pressure oil to the oil tank when not operated. The brake mechanism is arranged on the primary side of the brake valve and adjusts the pressure so as to limit the maximum pressure of the hydraulic oil supplied from the hydraulic pump, and returns the resulting excess oil to the oil tank. And an accumulator that is disposed on the primary side of the brake valve and stores pressure oil pressure-adjusted by the relief valve.

The brake mechanism of each self-propelled construction machine shown in FIGS. 1 and later described in detail later is constructed based on such a conventional brake mechanism and includes the conventional brake mechanism. In understanding the brake mechanism of the bi-oil brake, please refer to FIG. 1 and its description. The brake mechanism of oil-by-oil brakes uses mineral oil as the hydraulic oil, while non-mineral oil has a lower viscosity than the mineral oil as the brake fluid. And there is little change in viscosity due to temperature change.

[0006]

In the conventional brake mechanism using the oil-by-oil brake, a non-mineral oil based oil having a small change in viscosity due to a temperature change is provided on the secondary side of the booster as a braking force transmitting medium. Although the brake fluid is used, the hydraulic fluid whose viscosity increases in a low temperature environment is used in the flow path from the hydraulic pump to the primary side of the booster. Therefore, in an environment below freezing, especially when the outside temperature is -10 °
In extremely low environments such as C and -20 ° C,
When the viscosity of the hydraulic oil is significantly increased, the viscous resistance increases, and the pressure loss in the discharge passage of the hydraulic oil from the booster to the oil tank increases.

In this case, even if the brake pedal is released from the state where the brake pedal is depressed and the brake valve is not operated, the hydraulic oil on the primary side of the booster is not discharged at all and a residual pressure is generated in the cylinder of the booster. As a result, a state occurs in which the brake is applied even though the brake pedal is not operated, and so-called drag occurs. When this drag occurs, the self-propelled construction machine travels with the brakes applied, causing travel resistance,
Problems such as an increase in fuel consumption and wear of the brake lining of the brake shoe occur.

[0008] The invention of this application has been made to solve such problems of the prior art, and its technical problem is to provide a brake for a self-propelled construction machine that does not cause dragging even when the outside air temperature is low. It is to provide a mechanism.

[0009]

SUMMARY OF THE INVENTION In order to solve these technical problems, the present invention provides a brake device driven by the hydraulic pressure of a brake fluid, and a hydraulic device which increases hydraulic pressure of hydraulic oil acting on a primary side to increase a hydraulic pressure on a secondary side. A booster that transmits the brake fluid to the brake device and supplies the fluid pressure to the brake device; a hydraulic pump that pressurizes hydraulic oil in the oil tank and supplies the pressure oil to the booster; A brake valve that can adjust the amount of pressurized oil supplied to the booster and shut off the flow of pressurized oil from the primary side to the secondary side when not in operation to discharge the secondary side pressurized oil, and the primary side of the brake valve And a relief valve that adjusts the pressure to limit the maximum pressure of the hydraulic oil supplied from the hydraulic pump and returns surplus oil to the oil tank. In a brake mechanism of a self-propelled construction machine having an accumulator for storing adjusted pressure oil, a connection circuit for connecting a discharge port of a brake valve for discharging pressure oil on a secondary side to a suction port side of a hydraulic pump. Was provided.

According to the present invention, when the brake valve is not operated after the operation of the self-propelled construction machine is started, the pressure oil of the oil pump passes through the relief valve. And returned to the oil tank,
While such a process is repeated, the hydraulic oil on the primary side of the booster is discharged through the discharge port of the brake valve, and the brake device is not operated. When the operator operates the brake valve in this state, the brake valve is switched to supply the pressure oil of the oil pump to the primary side of the booster while adjusting the supply amount of the pressure oil according to the operation amount, thereby operating the brake device. Activate.

Thereafter, when the operator releases the operation of the brake valve, the brake valve is switched to a non-operating state to cut off the flow of the pressure oil from the primary side to the secondary side and to operate the primary side of the booster. The oil is quickly discharged through the connection circuit while forcibly sucking the oil from the discharge port of the brake valve with an oil pump. Since the brake mechanism of the self-propelled construction machine of the present invention forcibly sucks the hydraulic oil of the booster with the oil pump when releasing the operation of the brake valve, the operation of the brake device is stopped. It can be quickly released, and no drag occurs even when the outside air temperature is low and the viscosity of the hydraulic oil is significantly increased.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will now be described with reference to FIGS. 1 to 5 showing concrete examples showing how the present invention is actually embodied. I do. FIG. 1 is a diagram showing a brake hydraulic circuit in a brake mechanism of a self-propelled construction machine according to a first embodiment of the present invention, and FIG. 2 is a self-propelled motor according to a second embodiment of the present invention. FIG. 3 is a diagram illustrating a hydraulic circuit for braking in a brake mechanism of a construction machine, and FIG. 3 is an example of a hydraulic circuit for traveling of a self-propelled construction machine controlled by a controller in association with the hydraulic circuit for braking in FIGS. 2 and 5. FIG. 4 is a diagram showing a brake hydraulic circuit in a brake mechanism of a self-propelled construction machine according to a third embodiment of the present invention, and FIG. 5 is a diagram showing a fourth embodiment of the present invention. FIG. 2 is a diagram illustrating a hydraulic circuit for braking in a brake mechanism of the self-propelled construction machine.

A brake mechanism of a self-propelled construction machine according to a first embodiment of the present invention will be described with reference to FIG.

In FIG. 1, reference numeral 21 denotes a wheel cylinder which constitutes a brake device which is driven by the hydraulic pressure of brake fluid, and 22 denotes a hydraulic pressure of hydraulic oil acting on a primary side which is increased and transmitted to a secondary side brake fluid. A booster for supplying the hydraulic pressure to the wheel cylinder 21; a brake hydraulic pump 23 for pressurizing hydraulic oil in an oil tank 24 and supplying the hydraulic oil to the booster 22; 24, an oil tank; The hydraulic oil supply to the booster 22 can be adjusted in accordance with the manipulated amount, and the flow of the hydraulic oil from the primary side to the secondary side is cut off during non-operation so that the secondary side hydraulic oil is supplied to the oil tank 24. The brake valve 26 is disposed on the primary side of the brake valve 25 and pressure is adjusted so as to limit the maximum pressure of the hydraulic oil supplied from the hydraulic pump 23, and excess oil is supplied to the oil tank 24. Relief valve, 27 a brake is arranged on the primary side of the valve 25 a relief valve 26 to feed
An accumulator 28 stores the pressure oil whose pressure has been adjusted by the above, and a check valve 28 prevents the backflow of the pressure oil in the accumulator 27.

The wheel cylinder 21 is extended when the brake fluid on the secondary side of the booster 22 is supplied, pushes and spreads the brake shoe 21a, and can brake the self-propelled construction machine. The booster 22 is configured to increase the pressure of hydraulic oil acting on the primary side by combining a ram cylinder 22a having a large cross-sectional area provided on the primary side and a ram cylinder 22b having a small cross-sectional area provided on the secondary side, thereby increasing the secondary pressure. To the side brake fluid. As described above, the hydraulic oil acting on the primary side of the booster 22 has a property of increasing viscosity in a low-temperature environment, whereas the brake fluid on the secondary side has a property of little change in viscosity due to temperature change. Have.
The supply and discharge of the hydraulic oil to and from the booster 22 are performed through a center joint 29.

The brake valve 25 is switched by an operator depressing a brake pedal 25a, and controls the flow of hydraulic oil on the primary side of the booster 22. That is, when the operator steps on the brake valve 25, the brake valve 25 is sequentially switched from the lower position to the center position and the upper position according to the amount of depression. When the brake pedal 25a is not depressed, the hydraulic pump 2 is switched to the lower position.
The supply port for supplying the pressure oil from 3 to the booster 22 is closed to shut off the flow of the pressure oil from the primary side to the secondary side, and to operate the primary side of the booster 22 (the secondary side of the brake valve 25). Open the drain port for draining the oil.
When the brake valve 25 is depressed to switch to the center position, both the supply port and the discharge port are closed, and when switched to the upper position, the supply port is opened and the discharge port is closed, and the booster 22 is closed according to the amount of depression.
The amount of pressure oil supplied to the booster 22 can be adjusted, and the pressure value of the hydraulic pressure output to the booster 22 can be adjusted.

The relief valve 26 is provided to protect the brake hydraulic circuit.
The pressure is set at least higher than the secondary pressure of the brake valve 25 and is set in consideration of the pressure value to be stored in the accumulator 27 and the like. The accumulator 27 includes the hydraulic pump 2
3 is provided to improve the responsiveness of the brake by accumulating the hydraulic pressure generated at 3, and also provided to enable the brake to be operated even when the hydraulic pump 23 is stopped by stopping the engine. ing. The devices described above are devices normally provided in a brake mechanism of an oil-by-oil brake.

The brake mechanism of the self-propelled construction machine shown in FIG. 1 is different from the brake mechanism of such an oil-by-oil brake in that a discharge port of a brake valve 25 for discharging hydraulic oil on the secondary side is connected to a hydraulic pump 23. Is provided with a connection circuit 20 connected to the suction port side. That is, a connection circuit 20 provided with a filter 20a connects between a flow path A for introducing hydraulic oil in the oil tank 24 to the hydraulic pump 23 and a discharge port of the brake valve 25, and the brake valve 25 Is switched to the lower position, the hydraulic oil supplied to the primary side of the booster 22 can be introduced from the discharge port of the brake valve 25 to the hydraulic pump 23 through the connection circuit 20 and the hydraulic oil introduction flow path A. I have to. The discharge port of the brake valve 25 is normally connected to the oil tank 24 via a flow path. In the present brake mechanism, such a discharge port is connected to the hydraulic pump 23.

In such a brake mechanism of a self-propelled construction machine, when the operator starts the operation of the self-propelled construction machine and drives the hydraulic pump 23 for braking, when the brake valve 25 is at the lower position in the drawing. That is, when the brake valve 25 is not operated, the pressure oil of the hydraulic pump 23 is
Since the flow to the booster 22 side is blocked by the brake valve 25, it is returned to the oil tank 24 through the relief valve 26, and such a process is repeated. The hydraulic oil on the primary side of the booster 22 is discharged through the discharge port of the brake valve 25, and the wheel cylinder 21 of the brake device is in a non-operating state.

In this state, when the operator operates the brake valve 25 by depressing the brake pedal 25a to apply a brake, the brake valve 25 is switched to the upper position after passing through the intermediate position, and the hydraulic oil is changed according to the operation amount. Oil pump 23 for the brake while adjusting the supply amount of
Is supplied to the primary side of the booster 22, and the wheel cylinder 21 is extended to operate the brake device. At this time, the brake valve 25 has its discharge port closed to prevent the hydraulic oil on the primary side of the booster 22 from being discharged to the connection circuit 20 side.

Thereafter, the operator operates the brake valve 2
5 is released, the brake valve 25 is switched to the lower position in the non-operating state to cut off the flow of the pressure oil from the primary side to the secondary side, and to release the hydraulic oil on the primary side of the booster 22 to the brake. The fluid is quickly discharged through the connection circuit 20 while being forcibly sucked by the brake oil pump 23 from the discharge port of the valve 25. Since the brake mechanism of the self-propelled construction machine forcibly sucks the hydraulic oil of the booster 22 by the oil pump 23 when the operation of the brake valve 25 is released, a brake device is formed. The operation of the wheel cylinder 21 can be quickly released, and no drag occurs even when the outside air temperature is low and the viscosity of the hydraulic oil is significantly increased. As a result, it is possible to prevent the self-propelled construction machine from traveling while the brakes are applied, thereby causing problems such as an increase in fuel consumption and wear of the brake lining of the brake shoe. It will not occur.

The solid matter contained in the hydraulic oil causes damage to control valves such as the hydraulic pump 23, the relief valve 26, and the check valve 28. In the example of FIG. Is provided, solid matter such as metal powder and packing dust generated on the primary side of the booster 22 can be removed by the filter 20a so as not to enter the hydraulic pump 23 and the control valve. These damages can be prevented. In the example of FIG. 1, the discharge port of the brake valve 25 is connected to the suction port side of the hydraulic pump 23 by the connection circuit 20, but the connection circuit 20 is provided with a branch flow path communicating with the oil tank 24, and When the temperature is not low, the flow path of the booster 22 may be switched by a switching valve or the like so as to be introduced into the branch flow path, so that the hydraulic oil can be discharged to the oil tank 24 through the branch flow path.

The basic example of the brake mechanism of the self-propelled construction machine of the present invention improved so as not to cause dragging even when the outside air temperature is low has been described. A description will be given of a brake mechanism of a self-propelled construction machine according to second to fourth embodiments of the present invention to which means for preventing the responsiveness of the vehicle from being deteriorated are added. 2 to 5 showing these brake mechanisms, the parts denoted by the same reference numerals as those in FIG. 1 represent the same parts as those in FIG. 1 and will not be described in detail.

As in the brake mechanism of FIG. 1, each of the brake mechanisms of these embodiments has a brake device including a wheel cylinder 21 and a brake shoe 21a driven by hydraulic pressure of brake fluid, and a primary side. Booster 22 which increases the hydraulic pressure of the hydraulic oil acting on the brake fluid, transmits the hydraulic pressure to the brake fluid on the secondary side, and supplies the hydraulic pressure to the wheel cylinder 21
And a hydraulic pump 23 that pressurizes the hydraulic oil in the oil tank 24 and supplies the hydraulic oil to the booster 22, and a hydraulic pump 23 that is operated by an operator to adjust the supply amount of the hydraulic oil to the booster 22 according to the operation amount. A brake valve 25 that shuts off the flow of hydraulic oil from the primary side to the secondary side when not operating and discharges hydraulic oil on the secondary side, and is supplied from the hydraulic pump 23 that is disposed on the primary side of the brake valve 25. A relief valve 26 for adjusting the pressure so as to limit the maximum pressure of the pressurized oil and returning the surplus oil to the oil tank 24, and a pressure oil which is disposed on the primary side of the brake valve 25 and whose pressure is adjusted by the relief valve 26 are stored. An accumulator 27 is provided. Also,
In such an oil-by-oil brake mechanism, a connection circuit 20 for connecting a discharge port of a brake valve 25 for discharging hydraulic oil on the secondary side to a suction port side of a hydraulic pump 23 is provided. The mechanism of the brake mechanism is provided as it is.

First, supplementary items of the brake mechanism according to the second embodiment of the present invention will be described with reference to FIGS.

Reference numeral 30 denotes an oil temperature sensor for detecting the temperature of the pressure oil supplied to the booster 22, and 31 denotes a relief valve 26 when the temperature of the hydraulic oil detected by the oil temperature sensor 30 falls below a set temperature. A solenoid valve for shutting off the pressure oil, which switches so as to shut off the flow of the pressure-adjusted pressure oil to the accumulator 27 side, 32 is provided when the temperature of the hydraulic oil falls below the set temperature. This is a solenoid valve for discharging the pressure oil that shuts off the flow of the pressure oil to the brake valve 25 and switches the pressure oil to be discharged to the oil tank 24.

The result of the detection of the temperature of the hydraulic oil by the oil temperature sensor 30 is sent to a controller 33 described later. Normally, the solenoid valves 31 and 32 are switched to the upper position as shown in FIG. 2 to open a flow path for supplying the hydraulic pressure of the pump 23 to the brake valve 25 side. Also,
When the temperature of the hydraulic oil falls below the set temperature, the solenoid valves 31 and 32 are switched to the lower position by the controller 33 to shut off the above-mentioned flow path. At this time, the solenoid valve 32 connects the primary side to the oil tank 24. And returns the pressure oil in the accumulator 27 to the oil tank 24.
Therefore, even if the brake valve 25 is operated, the brake cannot be applied.

The technical contents of the main part of the brake mechanism of the self-propelled construction machine have been described above. Next, the entire system will be described with reference to FIG.

FIG. 3 does not show the brake hydraulic circuit of FIG. 2 for convenience. In FIG. 3, reference numeral 14 denotes a forward / reverse switch as operating means for selectively switching the self-propelled construction machine so as to move forward, backward, or stop;
Reference numeral 33 denotes a detection result of the temperature of the operating oil by the oil temperature sensor 30 in the brake hydraulic circuit shown in FIG. 2, and based on the detection result, the solenoid valves 31 and 32 in the hydraulic circuit and a hydraulic circuit in the traveling hydraulic circuit described later. A controller 34 for controlling the forward / reverse switch 14 includes a normally closed contact 34a provided in an electric path of the forward / backward switch 14 and a solenoid 34b for energizing by an electric signal from the controller 33 to open the normally closed contact 34a. A relay 35 is a key switch for operating the self-propelled construction machine to enable driving of the traveling body at the start of operation, and is electrically connected to the controller 33.

The controller 33 stores, as a set temperature, a temperature near the limit (for example, an appropriate temperature of −10 ° C. or less) at which the viscosity of the hydraulic oil increases to adversely affect the responsiveness of the brake. The controller 33 is electrically connected to signal receiving portions of the solenoid valves 31 and 32, and receives an oil temperature sensor 30 input to the controller 33.
When the detection result becomes lower than the set temperature, an electric signal is output to the solenoid valves 31 and 32 to switch them to the lower position, and an electric signal is also output to the traveling relay 34 to open the electric circuit of the forward / reverse switch 14. And the forward / reverse switch 14 is not operated. Since the key switch 35 is connected to the controller 33, when the operator operates the key switch 35 to start the operation of the self-propelled construction machine, the controller 33 automatically operates.

In FIG. 3, the hydraulic circuit including the forward / reverse switch 14 shown above the traveling relay 34 is a traveling hydraulic circuit of a self-propelled construction machine for driving the traveling hydraulic motor 4. . Hereinafter, the traveling hydraulic circuit will be outlined.

The traveling hydraulic motor 4 drives a traveling body of a self-propelled construction machine such as a wheel of a wheel shovel.
The hydraulic motor 4 is driven to rotate by pressure oil generated by the traveling hydraulic pump 1, and the hydraulic pump 1 is driven by the engine 15. The direction and flow rate of the pressure oil of the hydraulic pump 1 is controlled by a pilot control valve 2, and is supplied to a hydraulic motor 4 via a counter balance valve 3.
The switching direction and the stroke amount of the pilot control valve 2 are controlled by the pilot pressure from the pilot hydraulic circuit to control the rotation direction and the rotation speed of the hydraulic motor 4. Can be controlled.

The pilot hydraulic circuit includes a pilot hydraulic pump 5 serving as a pilot pressure generating source, and a pilot valve connected to the hydraulic pump 5 for controlling the stroke of the pilot control valve 2 by the amount of depression of a pedal 6a. 6, a slow return valve 7 connected to the pilot valve 6 to delay return oil to the pilot valve 6, and a forward movement of the self-propelled construction machine connected to the slow return valve 7.
A forward / reverse switching valve 8 for selecting reverse or neutral (stop). The forward / reverse switching valve 8 is an electromagnetic switching valve, and is switched by a forward / reverse switch 14.

FIG. 3 shows a state where the forward / reverse switching valve 8 is in the neutral position (N position) and the pilot valve 6 is not operated. In this state, the pilot control valve 2 is also at the neutral position, the pressure oil from the traveling hydraulic pump 1 returns to the oil tank 9, and the self-propelled construction machine is stopped. When the forward / reverse switching valve 8 is switched to the forward position (F position) or the reverse position (R position) and the pedal 6a of the pilot valve 6 is depressed, the pilot pressure from the pilot hydraulic pump 5 is changed to the pilot pressure of the pilot control valve 2. Port 2a
Alternatively, the control valve 2 is sent to the pilot port 2b and the control valve 2 is switched. In that case, the opening amount of the pilot control valve 2 is adjusted according to the pilot pressure. As a result, the flow rate of the hydraulic oil from the hydraulic pump 1 is adjusted by the pilot control valve 2, and guided to the traveling hydraulic motor 4 via the pipe 12 a or 12 b and the counterbalance valve 3. The motor 4 is driven to drive the self-propelled construction machine.

During the traveling, the pedal 6a of the pilot valve 6
Is released, the pilot valve 6 shuts off the pilot pressure, and the outlet port thereof communicates with the tank 10. As a result, the pressure oil acting on the pilot port 2a or the pilot port 2b returns from the forward / reverse switching valve 8 to the oil tank 10 via the slow return valve 7 and the pilot valve 6. At this time, the return oil is throttled by the throttle 7a of the slow return valve 7, so that the pilot control valve 2 is gradually switched to the neutral position.

When the pilot control valve 2 returns to the neutral position, the pressure oil from the traveling hydraulic pump 1 returns to the oil tank 9, and the counter balance valve 3 also switches to the neutral position shown. As a result, the pressure oil from the traveling hydraulic motor 4 is throttled by the throttle 3a or the throttle 3b of the counter balance valve 3 and the throttle 2c in the pilot control valve 2, so that when the flow rate is large, the relief valve 11a Or relief valve 11
b opens and the large hydraulic brake works. When the discharge flow rate of the hydraulic motor 4 is reduced by the action of the hydraulic brake and the discharge flow rate of the hydraulic motor 4 is reduced, the relief valve 11a or 11b is closed, and the throttle valve 3a or 3b of the counter balance valve 3 and the throttle 2c in the pilot control valve 2 are connected. A circulation passage for returning the discharge oil of the hydraulic motor 4 to the hydraulic motor 4 is formed, and a small brake works on the hydraulic motor 4.

In the traveling hydraulic circuit of the self-propelled construction machine shown in FIG. 3, when the detection result of the oil temperature sensor 30 becomes equal to or lower than the set temperature, the controller 33 opens the electric circuit of the forward / reverse switch 14, so that the forward / backward movement is performed. Even if the switch 14 is operated, the traveling hydraulic motor 4 cannot be driven, and the self-propelled construction machine can be disabled. The hydraulic circuit for traveling of the self-propelled construction machine shown in FIG. 3 only has a relationship in this respect with the brake mechanism of the self-propelled construction machine according to the present invention, and the specific structure itself of the hydraulic circuit has a direct relationship. Not having. Therefore, the traveling hydraulic circuit may be replaced with another form as long as it is a hydraulic circuit that drives the traveling hydraulic motor.

The brake mechanism of the self-propelled construction machine according to the second embodiment described above has the functions and effects of the brake mechanism of the first embodiment already described with reference to FIG. To play.

In the brake mechanism according to the second embodiment, when the operator operates the key switch 35 to start the operation of the self-propelled construction machine, the operation detected by the oil temperature sensor 30 is performed. It is assumed that the oil temperature has dropped below the set temperature. Then, the temperature of the hydraulic oil is input to the controller 33, and the controller 33 issues an electric signal to the solenoid valve 31 for shutting off the pressure oil,
The solenoid valve 31 is switched to the lower position so that the pressure oil, the pressure of which has been adjusted by the relief valve 26, is blocked from flowing to the accumulator 27 side. Also, an electric signal is issued to the solenoid valve 32 for discharging the hydraulic oil, so that the hydraulic oil in the accumulator 27 is blocked from flowing to the brake valve 25 side and the hydraulic oil is discharged to the oil tank 24 so as to escape. Switch 32 to the down position.

When the solenoid valves 31 and 32 are switched to the lower position in this manner, the self-propelled construction machine cannot apply a brake even when the brake valve 25 is operated. If you accidentally drive
Runaway is dangerous. In response to such a problem, when the temperature of the hydraulic oil has dropped below the set temperature, the controller 33 also issues an electric signal to the traveling relay 34 to open its contact, and turns the forward / reverse switch 14 off. To As a result, even if the forward / reverse switch 14 is switched to the F position or the R position, the self-propelled construction machine cannot be run, thereby preventing the self-propelled construction machine from accidentally running away.

When the solenoid valve 31 is switched to the lower position, the hydraulic oil of the hydraulic pump for brake 23 flows through the solenoid valve 31 to the accumulator 27 side.
Therefore, the oil is returned to the oil tank 24 through the relief valve 26 and mixed with the hydraulic oil in the oil tank 24. The hydraulic oil in the oil tank 24 is again pressurized by the hydraulic pump 23, passes through the relief valve 26, is returned to the oil tank 24, and the circulation of the hydraulic oil is repeated. In the process, a considerable amount of frictional heat is generated when the pressure oil of the hydraulic pump 23 passes through the relief valve 26, and a little heat is also generated when the hydraulic oil is pressurized by the hydraulic pump 23. Therefore, the low-temperature hydraulic oil in the oil tank 24 is heated by these heats, and the oil temperature is gradually increased by repeating this process.

On the other hand, when the solenoid valve 32 is switched to the lower position, the pressure oil in the accumulator 27 is returned to the oil tank 24 through the solenoid valve 32 and is mixed with the hydraulic oil in the oil tank 24. As a result, the low-pressure oil stored in the accumulator 27 is also heated in the process of circulating the hydraulic oil, which is pressurized by the brake hydraulic pump 23 and passes through the relief valve 26. When the operating oil reaches a predetermined temperature (which may be the same temperature as the set temperature or a different temperature), the solenoid valve 3
1 and 32 are switched to the upper position in accordance with a command from the controller 33, and the flow of the pressure oil to the brake valve 25 side becomes possible, and the pressure oil of an appropriate temperature is stored in the accumulator 27. Further, since the contact of the traveling relay 34 is closed by a command from the controller 33 and the forward / reverse switch 14 is turned on, the self-propelled construction machine can be driven by switching the forward / backward switch 14. .

In the brake mechanism of the self-propelled construction machine according to the second embodiment, when the operation of the self-propelled construction machine is to be started, the outside air temperature is lowered and the viscosity of the hydraulic oil is significantly increased. Sometimes, after automatically raising the temperature of the hydraulic oil in the oil tank 24 by a command from the controller 33 to reduce the viscosity of the hydraulic oil, the hydraulic oil can be supplied to the booster 22 by operating the brake valve 25. Therefore, the pressure oil of the hydraulic pump for braking 23 is supplied to the booster 22.
, The pressure loss in the flow path for supplying the brake fluid to the vehicle can be reduced, and a decrease in brake responsiveness can be suppressed. Therefore,
According to the present brake mechanism, the response of the brake does not deteriorate even when the outside air temperature is low. In addition, the pressurized oil in the accumulator 27 is also returned to the oil tank 24 for warming, and the viscosity of the pressurized oil decreases, so that the original function of the accumulator 27 can be smoothly exerted and the brake oil can be used. Responsiveness can be further improved.

In the brake mechanism of this self-propelled construction machine,
When raising the temperature of the hydraulic oil in the oil tank 24,
Since the hydraulic oil is heated using a relief valve 26 normally provided in the brake mechanism of the bi-oil brake, the temperature of the hydraulic oil can be increased without newly installing a special heating means. Despite the provision of the working oil heating means, the structure does not become complicated.
Further, when the temperature of the hydraulic oil is increased by switching the solenoid valves 31 and 32 to the lower position and the brake is not effective, the self-propelled construction machine cannot run. Can be prevented, and driving safety can be ensured.

When the outside air temperature decreases and the viscosity of the hydraulic oil increases significantly, the resistance when the spool of the brake valve 25 is moved by depressing the brake pedal 25a increases due to the increase in the viscosity resistance. Required for the brake pedal 2
The operation of 5a may be felt heavy, resulting in a so-called brake feeling deterioration. In the brake mechanism of the self-propelled construction machine, when the temperature of the hydraulic oil falls below the set temperature, the viscosity of the hydraulic oil passing through the brake valve 25 when the brake pedal 25a is operated can be reduced. Can be reduced when the spool is moved by the brake pedal 25a. Therefore, according to the present brake mechanism, even if the outside air temperature is low, the operation of the brake pedal 25a can be prevented from becoming heavy, and the brake feeling does not deteriorate.

Next, supplementary items of the brake mechanism of the self-propelled construction machine according to the third embodiment will be described with reference to FIG.

The brake mechanism of this self-propelled construction machine is similar to the brake mechanism of the first embodiment shown in FIG. 1 except that the excess oil generated as a result of pressure adjustment by the relief valve 26 is prevented from flowing back and braked. An excess oil supply circuit 37 that can supply the secondary oil to the flow path on the secondary side of the valve 25 is provided. That is, the check valve 3 that prevents the back flow of the relief valve 26 to the secondary side between the secondary side flow path of the relief valve 26 and the secondary side flow path of the brake valve 25
The excess oil supply circuit 37 having the pressure control valve 6 is connected to supply the excess oil generated as a result of the pressure adjustment by the relief valve 26 to the secondary flow path of the brake valve 25.
This brake mechanism is different from the brake mechanism of FIG. 2 in that the oil temperature sensor 30 and the solenoid valves 31 and 32 are not provided. Therefore, neither the controller 33 nor the travel relay 34 is provided, and the controller 33 and the travel relay 34 can be provided independently of means such as the travel hydraulic circuit in FIG.

The brake mechanism of the self-propelled construction machine according to the third embodiment has the functions and effects of the brake mechanism of the first embodiment already described with reference to FIG. .

That is, in the brake mechanism of the third embodiment, when the operator starts the operation of the self-propelled construction machine and drives the hydraulic pump 23 for braking, the brake valve 25 is at the lower position in the figure. At the time, that is, when the brake valve 25 is not operated, the flow of the hydraulic oil of the hydraulic pump 23 to the booster 22 side is blocked by the brake valve 25, so that the hydraulic oil passes through the relief valve 26 and a part of the excess oil supply circuit 37. And the remainder is returned to the oil tank 24 and mixed with the hydraulic oil in the oil tank 24. The pressure oil shunted to the surplus oil supply circuit 37 is blocked by the check valve 36 to prevent the backflow 3, while the brake valve 25
After being discharged from the discharge port located below the brake valve 25, it is sucked and pressurized by the hydraulic pump 23 via the connection circuit 20 and the flow path A. The pressure oil sucked and pressurized by the hydraulic pump 23 and the pressure oil returned to the oil tank 24 pass through the relief valve 26 again, and are heated by frictional heat or the like at the time of passing through the relief valve 26. The hydraulic oil is warmed by repeating the above process.

On the other hand, the operator operates the brake pedal 25a.
When the brake valve 25 is switched to the upper position by stepping on, that is, when the brake valve 25 is operated, the pressure oil of the hydraulic pump 23 for brake is supplied to the booster 22 and the pressure oil on the secondary side of the brake valve 25 is connected. Circuit 20
Part of the pressurized oil heated when passing through the relief valve 26 is directly discharged from the secondary flow path of the brake valve 25 to the booster 22 via the surplus oil supply circuit. Supplied. Therefore, according to the brake mechanism of the self-propelled construction machine, even when the outside air temperature is low, it is possible to increase at least the temperature of the hydraulic oil flowing through the passage on the secondary side of the brake valve 25, The pressure loss in the inside can be reduced, and the responsiveness of the brake does not deteriorate. In particular, with this brake mechanism, even when the brake is applied shortly after starting operation,
Since the temperature of the hydraulic oil flowing in the flow path on the secondary side of the brake valve 25 can be immediately increased, unlike the second embodiment, no waiting time is required when starting operation. .

In the brake mechanism of the self-propelled construction machine, when the brake is applied shortly after the operation is started, the hydraulic oil in the oil tank 24 is also reduced by the above-described process in which the hydraulic oil repeatedly passes through the relief valve 26. Since the temperature of the hydraulic oil in the flow path on the primary side of the brake valve 25 is increased by heating, the responsiveness of the brake can be further improved. In the present brake mechanism, when increasing the temperature of the hydraulic oil in the oil tank, the hydraulic oil is heated using the relief valve 26 as in the second embodiment, so that a special heating The temperature of the hydraulic oil can be increased without newly providing a means, and the structure is not complicated.

Lastly, supplementary items regarding the brake mechanism of the self-propelled construction machine according to the fourth embodiment will be described with reference to FIGS.

The brake mechanism of the self-propelled construction machine uses the relief mechanism in the brake mechanism of the first embodiment described above when the temperature of the hydraulic oil detected by the oil temperature sensor 31 falls below the set temperature. A solenoid valve 31 for shutting off the pressure oil, which shuts off the flow of the pressure oil adjusted by the valve 26 to the accumulator 27 side, and an accumulator when the temperature of the hydraulic oil falls below the set temperature. A pressure oil discharge solenoid valve 32 for shutting off the pressure oil in 27 to the brake valve 25 side and switching the pressure oil to escape to the oil tank 24, and the temperature of the hydraulic oil is equal to or lower than the set temperature. When the contact point of the traveling relay 34 is opened, the traveling hydraulic motor 4 is operated even if the forward / reverse switch 14 is switched.
And a controller 33 that controls the self-propelled construction machine so that it cannot be driven and cannot travel.

In the brake mechanism of the fourth embodiment, the surplus oil supply circuit 37 in the brake mechanism of the third embodiment shown in FIG. 4 is added to such a brake mechanism. That is, a surplus oil supply circuit having a check valve 36 between the secondary flow path of the relief valve 26 and the secondary flow path of the brake valve 25 for preventing reverse flow of the relief valve 26 to the secondary side. 37 is connected so that surplus oil generated as a result of pressure adjustment by the relief valve 26 is prevented from flowing backward and supplied to the secondary flow path of the brake valve 25.

Therefore, the present brake mechanism can exhibit the basic functions and effects of the brake mechanism of the third embodiment in addition to the functions and effects of the brake mechanism of the second embodiment. That is, when the outside air temperature is low, the second
Solenoid valve 3 as in the brake mechanism of the embodiment of FIG.
1 is switched to the lower position, the low-temperature hydraulic oil in the oil tank 24 is heated by passing through the relief valve 26 after being pressurized by the brake hydraulic pump 23. The hydraulic oil warmed by the relief valve 26 and diverted to the surplus oil supply circuit 37 is sent to the secondary side of the brake valve 25 and discharged from the discharge port of the brake valve 25, and flows through the connection circuit 20 and the flow path A. After being sucked and pressurized by the hydraulic pump 23 via the passage, it is heated again through the relief valve 26. Some of these warmed hydraulic oils are
4 and the working oil in the oil tank 24 is heated by repeating these steps.

As a result, similarly to the brake mechanism of the second embodiment, it is possible to reduce the viscosity of the working oil in the oil tank 24 and reduce the pressure loss in the supply passage of the pressure oil to the booster 22. As a result, even if the outside air temperature is low, the responsiveness of the brake does not deteriorate. In addition, the viscosity of the pressure oil in the accumulator 27 also decreases, and
Can smoothly exhibit its original function, so that the responsiveness of the brake can be further improved. Further, when the temperature of the hydraulic oil is increased by switching the solenoid valves 31 and 32 to the lower position and the brake is not effective, the self-propelled construction machine cannot run. Can be prevented, and driving safety can be ensured.

In addition, when the outside air temperature is low, a part of the pressure oil heated at the time of passing through the relief valve 26 is braked via the surplus oil supply circuit 37, similarly to the brake mechanism of the third embodiment. Since the pressure is supplied directly to the booster 22 from the secondary flow path of the valve 25, the temperature of the hydraulic oil flowing in the secondary flow path of the brake valve 25 must always be increased when the brake is applied. Can be. Therefore, when the outside air temperature is low, at least the pressure loss in the flow path on the secondary side of the brake valve 25 can be reduced, and the responsiveness of the brake does not deteriorate. Although the present brake mechanism includes the surplus oil supply circuit 37 according to the brake mechanism of the third embodiment, the solenoid valves 31 and 32 are switched to the lower position and the temperature of the hydraulic oil is reduced in a state where the brake is not effective. To increase
Unlike the brake mechanism of the third embodiment, a slight waiting time is required when starting operation.

In particular, in the brake mechanism of the fourth embodiment, when the temperature of the hydraulic oil decreases, the brake valve 25 of the supply flow path of the pressure oil of the brake hydraulic pump 23 to the booster 22 is used. The hydraulic oil in the primary flow path can be raised mainly by the means according to the second embodiment, and the hydraulic oil in the secondary flow path of the brake valve 25 is mainly the third hydraulic oil. The oil temperature can be increased by the means according to the embodiment. Therefore, the means relating to both the brake mechanisms of the second embodiment and the third embodiment complement each other and can evenly increase the temperature of the hydraulic oil in the supply flow path to the booster 22, so that the brake Responsiveness can be further improved. When the temperature of the hydraulic oil in the primary and secondary flow passages of the brake valve 25 is increased in this way, the hydraulic oil in any of the flow passages is supplied to a relief mechanism normally provided in a brake mechanism of an oil-by-oil brake. Since the valve 26 is used to heat by utilizing the frictional heat twice, the temperature of the hydraulic oil can be increased without newly installing a special heating means, and the structure is not complicated. Rather, the structure itself is technically quite reasonable.

As described above, the present invention provided with the drag prevention means can be embodied by providing various additional means. However, as shown in the second to fourth embodiments, By realizing the brake mechanism of self-propelled construction machinery, even when the outside temperature is low, dragging and deterioration of brake responsiveness do not occur, and it is possible to secure the same good brake performance as at normal temperature. Thus, a braking performance suitable for a cold region can be obtained.

[0060]

As is apparent from the above description, the brake mechanism of the self-propelled construction machine of the present invention employs the means described in the section of "Means for Solving the Problems". No dragging occurs even at low temperatures. As a result, it is possible to prevent the self-propelled construction machine from traveling while the brakes are applied, thereby causing problems such as an increase in fuel consumption and wear of the brake lining of the brake shoe. It will not occur.

When the brake mechanism of the self-propelled construction machine according to the present invention is embodied, such basic effects can be exerted if embodied as described in claim 2 or claim 3. In addition, the responsiveness of the brake does not deteriorate even when the outside temperature is low. When the temperature of the hydraulic oil in the oil tank is raised, the resulting brake mechanism of the self-propelled construction machine uses the relief valve normally provided in the brake mechanism of the oil-by-oil brake. The temperature of the hydraulic oil can be increased without installing special heating means, and the structure can be complicated despite the addition of the hydraulic oil heating means. Absent. The same applies when the brake mechanism of the self-propelled construction machine described in claim 2 is embodied as described in claim 3. Therefore, according to the brake mechanism of the self-propelled construction machine according to claims 2 and 3 of the claims, even when the outside air temperature is low, dragging and deterioration of brake responsiveness do not occur. Similar good braking performance can be ensured, and suitable braking performance in cold regions can be obtained.

In particular, when the brake mechanism of the self-propelled construction machine of the present invention is embodied as described in claim 2, the pressurized oil in the accumulator is also returned to the oil tank to be heated. Therefore, the original function of the accumulator can be smoothly exhibited, and the responsiveness of the brake can be further improved. In addition, when switching the switching valve for shutting off the hydraulic oil and the switching valve for discharging the hydraulic oil and raising the temperature of the hydraulic oil in a state where the brake is not effective, the self-propelled construction machine cannot be driven. It can also prevent accidental runaway of the construction equipment, and also ensure the safety of driving. Further, when the temperature of the hydraulic oil drops below the set temperature, the viscosity of the hydraulic oil passing through the brake valve during operation of the brake valve can be reduced, so that the resistance when moving the spool of the brake valve increases. There is nothing. Therefore, according to the brake mechanism of the self-propelled construction machine of the present invention, even if the outside air temperature is low, the brake feeling does not deteriorate.

In particular, when the brake mechanism of the self-propelled construction machine according to the present invention is embodied as described in claim 3, even when the brake is applied shortly after the start of operation, the brake valve can be used. The temperature of the hydraulic oil flowing in the flow path on the next side can be immediately increased, and no waiting time is required when starting operation. Also, when the brake is applied shortly after the start of operation, the hydraulic oil in the oil tank is warmed and the temperature of the hydraulic oil in the primary flow path of the brake valve is also increased, so that the responsiveness of the brake is improved. It can be further improved.

Further, when the brake mechanism of the self-propelled construction machine described in claim 2 is embodied as described in claim 3, the brake mechanism of the self-propelled construction machine of the present invention is used. In addition to exhibiting the same effects as when embodied as described in claim 2, the basic effects when embodied as described in claim 3 can also be exhibited. And when the temperature of the hydraulic oil drops,
When embodied as the former, it is possible to increase the oil temperature of the hydraulic oil in the supply passage of the hydraulic oil of the hydraulic pump to the booster, particularly the hydraulic oil in the passage on the primary side of the brake valve. When it is embodied, the oil temperature can be raised especially for the hydraulic oil in the flow path on the secondary side of the brake valve, so that the means according to claim 2 and the means according to claim 3 complement each other and booster The temperature of the hydraulic oil in the supply flow path to the oil can be uniformly increased, and the responsiveness of the brake can be further improved. When raising the temperature of the hydraulic oil in the primary and secondary flow paths of the brake valve in this way, the hydraulic oil in either flow path uses a relief valve normally provided in the brake mechanism of an oil-by-oil brake. In addition, because the frictional heat is used twice to heat, there is no need to newly install special heating means, which not only complicates the structure but also makes the structure itself extremely technically It will be reasonable.

[Brief description of the drawings]

FIG. 1 is a diagram showing a brake hydraulic circuit in a brake mechanism of a self-propelled construction machine according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a brake hydraulic circuit in a brake mechanism of a self-propelled construction machine according to a second embodiment of the present invention.

FIG. 3 is a diagram showing an example of a traveling hydraulic circuit of a self-propelled construction machine controlled by a controller in connection with the brake hydraulic circuits of FIGS. 2 and 5;

FIG. 4 is a diagram showing a brake hydraulic circuit in a brake mechanism of a self-propelled construction machine according to a third embodiment of the present invention.

FIG. 5 is a diagram showing a brake hydraulic circuit in a brake mechanism of a self-propelled construction machine according to a fourth embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 hydraulic pump for traveling 2 pilot-type control valve 4 hydraulic motor for traveling 5 hydraulic pump for pilot 6 pilot valve 6a pedal for pilot valve 7 slow return valve 8 forward / backward switching valve 9,10 oil tank 14 forward / backward switch 15 Engine 20 Connection circuit 20a Filter 21 Wheel cylinder 22 Booster 23 Hydraulic pump for brake 24 Oil tank 25 Brake valve 26 Relief valve 27 Accumulator 28 Check valve 29 Center joint 30 Oil temperature sensor 31 Solenoid valve for shutting off pressure oil 32 Pressure oil discharge Valve for controller 33 Controller 34 Traveling relay 35 Key switch 36 Check valve 37 Excess oil supply circuit

Continued on front page F term (reference) 3D048 AA03 BB41 CC51 HH14 HH15 HH16 HH32 HH38 HH50 HH66 HH67 RR13 3H082 AA01 AA08 CC02 DA17 DA23 DA46 DA48 DB23 DB26 DB36 EE01

Claims (3)

[Claims] 1. A brake device driven by the hydraulic pressure of a brake fluid, and a hydraulic pressure of hydraulic oil acting on a primary side is increased and transmitted to a secondary side brake fluid to supply the hydraulic pressure to the brake device. A booster, a hydraulic pump that pressurizes hydraulic oil in the oil tank and supplies the pressurized oil to the booster, and a hydraulic pump that is operated by an operator to adjust the amount of pressurized oil supplied to the booster according to the amount of operation A brake valve that shuts off the flow of hydraulic oil from the primary side to the secondary side and discharges the hydraulic oil on the secondary side, and a maximum pressure of the hydraulic oil that is provided on the primary side of the brake valve and that is supplied from a hydraulic pump. Self-propelled construction equipped with a relief valve that adjusts pressure so as to restrict it and returns surplus oil to the oil tank, and an accumulator that is provided on the primary side of the brake valve and stores pressure oil whose pressure is adjusted by the relief valve A brake mechanism for a self-propelled construction machine, wherein a connection circuit is provided for connecting a discharge port of a brake valve for discharging hydraulic oil on a secondary side to a suction port side of a hydraulic pump in a mechanical brake mechanism. . 2. The brake mechanism for a self-propelled construction machine according to claim 1, wherein when the temperature of the hydraulic oil falls below a set temperature, the pressure oil regulated by the relief valve flows to the accumulator side. A switching valve for shutting off the pressure oil to shut off the pressure, and when the temperature of the hydraulic oil falls below the set temperature, the pressure oil in the accumulator is interrupted from flowing to the brake valve side and the pressure is reduced. A switching valve for discharging pressure oil that switches so as to allow oil to escape to the oil tank, and travel control means that prevents the self-propelled construction machine from traveling when the temperature of the hydraulic oil falls below the set temperature are provided. Brake mechanism for self-propelled construction machinery. 3. The brake mechanism for a self-propelled construction machine according to claim 1, wherein a surplus oil generated as a result of pressure adjustment by the relief valve is prevented from flowing back to the secondary side of the brake valve. A brake mechanism for a self-propelled construction machine, comprising a surplus oil supply circuit capable of supplying a surplus oil to a flow passage.