JP2512475Y2 - Full hydraulic power brake device with auxiliary braking device for work - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The full hydraulic power brake device with an auxiliary braking device for work according to the present invention applies a large braking force to each wheel during work on a truck or various construction vehicles. Used to give.

(Prior art and its problems) For trucks and various construction vehicles, in order to prevent the vehicle from inadvertently moving during work, use a normal parking brake that applies braking force only to some wheels. In addition, a work auxiliary braking device that applies a braking force to all wheels may be provided.

In such a work auxiliary braking device, a wheel cylinder attached to each wheel has a pressure P ₀ (e.g., a pressure slightly lower than the maximum pressure P _max at the time of normal braking for stopping the traveling vehicle). P ₀ ≦ 0.75P _max ) is added, and it is required to have the function of maintaining the pressure even without pressing the brake pedal.

For this reason, work auxiliary braking devices of various structures have been proposed and are actually used. However, all of the conventionally known work auxiliary braking devices are combined brake devices that use both hydraulic pressure and pneumatic pressure. Or a brake device having a vacuum pressure booster, the structure is complicated, and the brake device for a vehicle not having a work auxiliary brake device is used for the work afterwards. It was not possible to add the function of the auxiliary braking device.

The all-hydraulic power brake device with a work auxiliary braking device of the present invention eliminates the above-mentioned inconvenience.

(Means for Solving the Problem) The full hydraulic power brake device with an auxiliary braking device for work according to the present invention comprises a pressure oil supply means and a pressure oil required for regular braking for stopping a traveling vehicle. An accumulator for a regular brake that holds a, an accumulator for an auxiliary brake that retains pressure oil, an oil supply port that communicates with the accumulator for a regular brake, and a discharge port that communicates with a wheel cylinder provided on each wheel, A brake valve that displaces the spool in the cylinder space by depressing the brake pedal so that the oil supply port and the discharge port communicate with each other, and a pilot cylinder provided at a part of the brake valve and at one end of the cylinder space. And a pilot port that communicates with the other end of the cylinder space. Is provided in the middle of the piping that communicates the reaction chamber with the pilot port and the auxiliary brake accumulator, and connects the pilot port to the auxiliary brake accumulator and the pilot port to the oil tank. And a switching valve for switching.

(Operation) The operation of the full hydraulic power brake device with a work auxiliary braking device of the present invention configured as described above is as follows.

When performing normal braking such as stopping the running vehicle, the switching valve is switched to a state in which the pilot port communicates with the oil tank.

When the brake pedal is depressed in this state, the oil supply port and the discharge port of the brake valve communicate with each other, and the pressure oil stored in the regular brake accumulator is sent to the wheel cylinders provided on each wheel for braking.

Further, since the work is performed while the vehicle is stopped, the switching valve is switched to the state in which the pilot port and the auxiliary brake accumulator are in communication when the auxiliary braking device for work is operated.

As a result, the pressure oil stored in the accumulator for the auxiliary brake is sent to the pilot cylinder provided at one end of the cylinder space of the brake valve through the pilot port, and the spool in the cylinder space is displaced to cause the brake valve to operate. The oil supply port and the discharge port are communicated with each other, and the pressure oil in the service brake accumulator is sent to a wheel cylinder provided on each wheel to perform braking.

As a result, when the oil pressure in the reaction chamber rises, a force that tends to displace the spool in the opposite direction is generated, and the communication between the oil supply port and the discharge port tends to be cut off. The movement of the spool in the cylinder space is stopped when the pressing force based on the hydraulic pressure in the reaction chamber becomes equal to the pressing force based on the hydraulic pressure introduced from the auxiliary brake accumulator to one end of the cylinder space. In this state, the hydraulic pressure of a magnitude commensurate with the hydraulic pressure fed from the auxiliary brake accumulator is fed to the wheel cylinder of each wheel through the discharge port.

(Embodiment) Next, the present invention will be described in more detail with reference to the illustrated embodiment.

1 to 4 show an embodiment of an all-hydraulic power brake device with an auxiliary braking device for work according to the present invention. FIG. 1 is a schematic diagram showing the construction of a hydraulic circuit, and FIG. 2 is a rear view of a brake valve. FIG. 3 is a sectional view taken along the line AA in FIG. 2, and FIG. 4 is an electric circuit diagram showing a control circuit.

In FIG. 1, reference numeral 1 denotes an oil pump which constitutes a pressure oil supply means, and pressure oil which is sucked from the oil tank 2 to the oil pump 1 and pressurized in the oil pump 1 is supplied to the check valve 3 Through the unload relief valve 4 in which the oil is incorporated into the main oil feed pipe 5. First and second branched oil supply pipes 6a, which are branched from the downstream end of the main oil supply pipe 5 and are parallel to each other,
The downstream end of 6b is connected to the oil supply ports 9a and 9b of the brake valve 10 which is controlled to be opened and closed by depressing the brake pedal 7 or by sending pressure oil to the pilot port 8 which will be described later.

In the middle of the first and second branch oil supply pipes 6a and 6b, the oil supply ports 9a and
Check valves 11 and 11 for supplying pressure oil only to 9b, and accumulators 12 and 12 for service brakes that retain the pressure oil required for service braking to stop the running vehicle.
And are provided. An auxiliary brake accumulator 13 is provided in series with the main brake accumulators 12, 12 in the middle of the main oil supply pipe 5.

The discharge ports 14 and 14 of the brake valve 10 are communicated with the wheel cylinders (not shown) attached to the wheels 16 and 16 through branch pipes 15 and 15, respectively. , 9b and discharge port 14,
When communicating with 14, the relatively high-pressure oil stored in the above-mentioned regular brake accumulators 12, 12 is sent to each wheel cylinder for braking.

On the other hand, the downstream end of the third branch oil feed pipe 17 branched from the downstream end of the main oil feed pipe 5 communicates with the cylinder chamber 19 of the parking brake spring brake 18. The parking brake spring brake 18 obtains a braking force by the elastic force of the spring 20, and when the brake is not applied, the pressure oil in the auxiliary brake accumulator 13 is fed into the cylinder chamber 19 to resist the elastic force of the spring 20. Then, the lever 21 is rotated.
For this reason, a parking brake electromagnetic switching valve 22 is provided in the middle of the third branch oil feed pipe 17 to control the feeding of pressure oil into the cylinder chamber 19 and its stop.

As described above, the first and second branch oil supply pipes 6a, 6b leading to the service brake accumulators 12, 12 are connected to the oil supply ports 9a, 9b connecting the downstream ends of the oil supply pipes 9a, 9b and the wheel cylinders provided on the wheels 16, 16. The brake valve 10 having the discharge ports 14 and 14 communicating with each other and the pilot port 8 is configured as described below.

2 to 3 showing the brake valve 10 in detail, in a cylinder space 24 provided in the main body 23, a primary spool 25 and a secondary spool 26 are arranged in series in the vertical direction in series with each other. Each is provided movably along the cylinder space 24. The base end portion of the brake pedal 7 is pivotally supported on the upper surface of a flange portion 27 provided on the outer periphery of the upper end portion of the main body 23, and the roller 28 pivotally supported at the middle portion of the lower surface of the brake pedal 7 is pressed by a pressing cylinder 29. Abut on the upper surface of.

A sleeve 30 supported on the outer periphery of the upper end of the primary spool 25 is vertically movably fitted to the inside of the pressing cylinder 29 formed in the shape of a bottomed cylinder having an opening at the bottom, and the inner periphery of the lower end of the pressing cylinder 29 is mounted. The stop ring 31 mounted on the surface prevents the sleeve 30 from coming out from the inside of the pressing cylinder 29. A compression spring 32 is provided between the lower surface of the pressing cylinder 29 and the upper surface of the sleeve 30 so that
It gives 30 downward elasticity.

On the other hand, on the upper part of the primary spool 25, a pilot cylinder 33 that opens to the upper end surface of the primary spool 25 is provided, and the upper end surface of the pilot plunger 34 fitted to the pilot cylinder 33 is inserted through the seat plate 35. It is pressed against the lower surface of the pressing cylinder 29. The pilot port 8 opened on the upper side surface of the main body 23 is
The large diameter portion 36 formed on the inner peripheral surface of the upper end of the above and a small through hole 37 formed in the primary spool 25 can always communicate with the pilot cylinder 33. The pilot port 8 is provided at the downstream end of the main oil feed pipe 5,
They communicate with each other via a fourth branched oil feed pipe 38. Then, in the middle of the fourth branch oil feed pipe 38, a pressure reducing valve 39 and an auxiliary brake electromagnetic switching valve 40 are arranged in order from the main oil feed pipe 5 side.
They are provided in series with each other (Fig. 1). The auxiliary brake electromagnetic switching valve 40 among them has a state in which the pilot port 8 communicates with the auxiliary brake accumulator 13.
A state in which the pilot port 8 is communicated with the oil tank 2 can be freely switched.

On the other hand, a reaction chamber 41 that opens to the lower end surface of the secondary spool 26 is provided in the lower portion of the secondary spool 26, and the lower end surface of the reaction plunger 42 fitted in the reaction chamber 41 is fixed to the lower end surface of the main body 23. It is abutted against the upper surface of the lid 43 that has been removed. Further, a compression spring 45 is provided between the upper surface of the lid body 43 and the lower surface of the seat plate 44 supported on the outer peripheral surface of the lower end portion of the secondary spool 26, so that the secondary spool 26 is provided with an upward elastic force. Granted.

In addition, a small diameter portion is provided on the outer peripheral surface of the intermediate portion of the primary spool 25.
46 on the outer peripheral surface of the intermediate portion of the secondary spool 26.
When the primary, secondary, and spools 25, 26 are formed downward, the small-diameter portions 46, 47 form the inner peripheral surface side openings of the oil supply ports 9a, 9b and the inner peripheral surfaces of the discharge ports 14, 14, respectively. The pressure oil is sent from the oil supply ports 9a, 9b to the discharge ports 14, 14 in alignment with the surface side opening. When the primary and secondary spools 25 and 26 are raised, the small diameter portions 46 and 47 are aligned with the large diameter portions 48 and 48 formed on the inner peripheral surface of the cylinder space 24, and the discharge ports 14 are ,14
And the discharge passage 62 (FIG. 1) are in communication with each other so that the pressure oil in the wheel cylinder provided in each wheel 16, 16 can be returned to the oil tank 2.

Further, the small diameter portion 47 on the outer peripheral surface of the secondary spool 26 and the reaction chamber 41 are communicated with each other through a small through hole 49 so that the same hydraulic pressure as that of the discharge port 14 portion is introduced into the reaction chamber 41. .

In the illustrated embodiment, the primary spool 25
At the lower end of the primary spool 25, another reaction chamber 50 that opens to the lower end surface of the primary spool 25 is also provided.
The lower end surface of the reaction plunger 51 fitted in the reaction chamber 50 is abutted against the upper end surface of the bolt 52 fixed to the upper end surface of the secondary spool 26.

A portion of the sleeve 54, which is externally fitted to the bolt 52 and has an elastic force directed upward by the compression spring 53, near the outer periphery of the upper surface, is a cylindrical portion 55 formed at the lower end portion of the primary spool 25.
It hits the bottom edge of. The another reaction chamber 50 and the small diameter portion 46 are communicated with each other through the small through hole 56 so that the same hydraulic pressure as that of the discharge port 14 portion is introduced into the other reaction chamber 50.

Among the above-mentioned components constituting the hydraulic circuit, the parking brake electromagnetic switching valve 22 and the auxiliary brake electromagnetic switching valve 40 are provided.
Are controlled by a control circuit as shown in FIG.

In FIG. 4, 57 is a parking brake switch,
58 is a parking brake relay that opens the contacts by energizing the coil by closing the parking brake switch 57.
Reference numeral 59 is a parking brake indicator light indicating that the parking brake is in use, 60 is an auxiliary brake switch, and 61 is an auxiliary brake indicator light indicating that the auxiliary brake is in use.

Since the switching of the auxiliary brake electromagnetic switching valve 40 is controlled by the control circuit having such a configuration, the auxiliary brake for work cannot be operated unless the parking brake is in use, and the vehicle cannot be operated during traveling. It is possible to eliminate the risk of accidentally operating the auxiliary brake.

The operation of the fully hydraulic power brake device with a work auxiliary braking device of the present invention constructed as described above is as follows.

When performing normal braking such as stopping the running vehicle, the auxiliary brake electromagnetic switching valve 40 is connected to the oil tank 2 through the pilot port 8 of the brake valve 10 as shown in FIG. Switch to the state that allows it. Further, the electromagnetic switching valve 22 for the parking brake is switched to the state opposite to that shown in FIG. 1 to send the pressure oil into the cylinder chamber 19 of the spring brake 18 for the parking brake.

In this state, depress the brake pedal 7 and press the compression spring 3
2.By lowering the primary and secondary spools 25 and 26 through the sleeve 30, the oil supply ports 9a and 9b and the discharge ports 14 and 14 of the brake valve 10 are connected to the spools 25 and
The pressure oil stored in the service brake accumulators 12 and 12 communicates with each other through the small diameter portions 46 and 47 formed on the outer peripheral surface of the intermediate portion of 26, and is fed to the wheel cylinders provided to the wheels 16 and 16. Braking is performed.

As the oil supply ports 9a and 9b and the discharge ports 14 and 14 communicate with each other, the reaction chambers 41 and 50 have the same hydraulic pressure as that existing in the discharge ports 14 and 14, so that the primary, The secondary spools 25 and 26 are pushed upward by the force corresponding to this hydraulic pressure, and the compression springs 32 and 53 are compressed. Therefore, the brake pedal 7 receives a reaction force commensurate with the pressure oil existing in the discharge ports 14, 14.

Next, since the work is performed while the vehicle is stopped, when the work auxiliary braking device is operated, the auxiliary brake electromagnetic switching valve 40 is set to the pilot port, contrary to the state shown in FIG. 8 and the auxiliary brake accumulator 13 are connected to each other.

As a result, the pressure oil stored in the auxiliary brake accumulator 13 is decompressed by the pressure reducing valve 39, and then fed into the pilot cylinder 33 through the pilot port 8, the large diameter portion 36, and the small through hole 37. Cylinder
Push the pilot plunger 34 out of 33. In this way, the reaction of the force that pushes out the pilot plunger 34 causes the primary, secondary, and both spools in the cylinder space 24.
25 and 26 are displaced downward so that the oil supply ports 9a and 9b of the brake valve 10 and the discharge ports 14 and 14 communicate with each other.

As a result, the pressure oil in the service brake accumulator 12 is sent to the wheel cylinders provided on the wheels 16, 16 for braking.

As a result of introducing the pressure oil in the service brake accumulator 12 into the discharge ports 14 and 14, the reaction chamber
When the hydraulic pressure in 41, 50 rises, a force is generated to displace the primary, secondary, and both spools 25, 26 in opposite directions, and the communication between the oil supply ports 9a, 9b and the discharge ports 14, 14 is cut off. There is a tendency to sag. The movement of the spools 25 and 26 in the cylinder space 24 depends on the reaction chambers described above.
When the pressing force based on the hydraulic pressure in 41, 50 becomes equal to the pressing force based on the hydraulic pressure introduced into the pilot cylinder 33 from the service brake accumulator 12 (the cross-sectional area of the reaction chambers 41, 50 and the pilot cylinder 33 If the cross-sectional area of is equal), stop. In this state, the wheel cylinders of the wheels 16 and 16 through the discharge ports 14 and 14 are in a state in which the hydraulic pressure of a magnitude corresponding to the hydraulic pressure controlled by the pressure reducing valve 39 is still supplied. .

The full hydraulic power brake device with an auxiliary braking device for work of the present invention is constructed and operates as described above, but if the full hydraulic power brake device has a parking brake, the brake valve 10 is replaced and the pressure reducing valve 39 is used. The function of the auxiliary braking device for work can be added later only by adding the fourth branched oil feed pipe 38 provided with the electromagnetic switching valve 40 for auxiliary brake.

In addition, in order to set the hydraulic pressure applied to the wheel cylinders of the wheels 16 and 16 to a low value in accordance with the operation of the auxiliary braking device,
As in the illustrated embodiment, an accumulator for auxiliary brake
A pressure reducing valve 39 is provided between 13 and the pilot port 8,
The reaction chamber of the pilot cylinder 33
It may be smaller than the cross-sectional area of 41. In this case, the pressure reducing valve 39 can be omitted.

(Effect of the Invention) Since the full hydraulic power brake device with a work auxiliary braking device of the present invention is constructed and operates as described above, it can be manufactured at a relatively simple structure at low cost, and the work auxiliary braking device is The function of the work auxiliary braking device can be added later to the vehicle braking device that does not have it.

[Brief description of drawings]

1 to 4 show an embodiment of an all-hydraulic power brake device with an auxiliary braking device for work according to the present invention. FIG. 1 is a schematic diagram showing the construction of a hydraulic circuit, and FIG. 2 is a rear view of a brake valve. FIG. 3 is a sectional view taken along the line AA in FIG. 2, and FIG. 4 is an electric circuit diagram showing a control circuit. 1: Oil pump, 2: Oil tank, 3: Check valve, 4: Unload relief valve, 5: Main oil supply pipe, 6a: First branch oil supply pipe, 6b:
Second branch oil pipe, 7: Brake pedal, 8: Pilot port, 9a, 9b: Oil supply port, 10: Brake valve, 11: Check valve, 12: Accumulator for regular brake, 13: Accumulator for auxiliary brake, 14: Discharge port, 15: Branch pipe, 1
6: Wheels, 17: Third branch oil supply pipe, 18: Spring brake for parking brake, 19: Cylinder chamber, 20: Spring, 21: Lever, 2
2: Electromagnetic switching valve for parking brake, 23: Main body, 24: Cylinder space, 25: Primary spool, 26: Secondary spool,
27: Flange part, 28: Roller, 29: Press cylinder, 30: Sleeve,
31: Stop ring, 32: Compression spring, 33: Pilot cylinder, 34: Pilot plunger, 35: Seat plate, 36: Large diameter part, 37: Small through hole, 38: Fourth branch oil pipe, 39: Pressure reducing valve, 40: Solenoid switching valve for auxiliary brake, 41: Reaction chamber, 4
2: Reaction plunger, 43: Lid, 44: Seat plate, 45: Compression spring, 46, 47: Small diameter part, 48: Large diameter part, 49: Small through hole, 50: Reaction chamber, 51: Reaction plunger, 52 :
Bolt, 53: Compression spring, 54: Sleeve, 55: Cylindrical part, 56: Small through hole, 57: Parking brake switch, 58: Parking brake relay, 59: Parking brake indicator light, 60: Auxiliary brake switch, 61: auxiliary brake indicator light, 62: discharge passage.

Claims (1)

(57) [Scope of utility model registration request] Claim: What is claimed is: 1. A pressure oil supply means, a service brake accumulator for holding pressure oil required for normal braking for stopping a running vehicle, and an auxiliary brake for holding pressure oil. Accumulator, an oil supply port leading to the above-mentioned regular brake accumulator, and a discharge port leading to a wheel cylinder provided on each wheel, and the spool is displaced in the cylinder space by depressing the brake pedal. And a pilot port provided in a part of the brake valve, the pilot port communicating with a pilot cylinder provided in one end portion of the cylinder space, and the discharge port portion provided in the other end of the cylinder space. Reaction chamber that introduces the same hydraulic pressure as the above, pilot port and auxiliary brake A complete auxiliary brake system for work, which is provided in the middle of the piping that communicates with the accumulator and consists of a switching valve that switches between the state in which the pilot port is in communication with the auxiliary brake accumulator and the state in which the pilot port is in communication with the oil tank. Hydraulic power brake device.