JPH07149229A - Auxiliary brake combined type brake device - Google Patents

Abstract

PURPOSE:To provide an auxiliary brake combined type brake device devised to secure braking force as a cutoff valve and certainly works even at the time when an exhaust valve has a trouble. CONSTITUTION:An input port 51 is formed on the upper end part of a valve housing 50, a control port 52 and an output port 53 are formed on the side surface and an exhaust port 54 is formed on the lower end part. The control port 52 is connected to a brake valve through an air piping 48, the input port 51 to an air master through an air piping 44 and the output port 53 to an exhaust valve through an air piping 45. In the valve housing 50, a control piston 56 and a valve body 57 are arranged, and a return spring 58 to energize the control piston 56 upward and a return spring 59 to energize the valve body 57 dowanward are provided. A seat surface 60 with which the valve body 57 makes contact is formed on a communicating part of the input port 51 and the output port 53, and a communicating hole 61 communicated to the exhaust port 54 is formed on the control piston 56.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auxiliary brake combined type brake device for braking a large bus or the like, and more particularly to a technique for securing a braking force when an exhaust valve fails.

[0002]

Friction brakes such as drum brakes and disc brakes operated by brake pedals are generally used as service brakes for automobiles. However, the friction brake causes a fade phenomenon and a vapor lock phenomenon when it is frequently used on a long downhill, and the brake shoes and brake pads are worn out, which requires a lot of inspection and maintenance. Running costs tended to be high. Further, since the friction brake converts kinetic energy into heat and releases it into the atmosphere during braking, in a route bus or the like that frequently starts and stops,
There was also a problem from the viewpoint of energy saving.

Therefore, in a large vehicle such as a bus or a truck, an exhaust brake and a braking energy regenerating device for recovering kinetic energy and utilizing the kinetic energy at the time of starting or accelerating are used as an auxiliary brake for assisting braking by a service brake. Conventionally used. The braking energy regeneration device includes a flywheel type and a power generation type.
The pressure-accumulation type disclosed in Japanese Patent No. 64900, Japanese Patent Publication No. 5-1168, etc. is the mainstream in terms of performance and cost. This braking energy regenerative device has a hydraulic pump / motor connected between a hydraulic oil tank and an accumulator. The pump / motor is connected to the power transmission system member and operates as a pump when the vehicle is braked to pump the hydraulic oil in the hydraulic oil tank to the accumulator. Further, when the vehicle starts or accelerates, high pressure hydraulic oil is supplied from the accumulator to the pump / motor, and the pump / motor is operated as a motor to drive the drive wheels of the vehicle.

For example, in a braking device that also uses this type of braking energy regenerating device (auxiliary brake), the contribution ratio between the service brake and the auxiliary brake during braking is appropriately changed based on the accumulated pressure of the accumulator, the vehicle speed, and the like. There is. In order to perform such control, the auxiliary brake is provided with various hydraulic control solenoid valves and the like to perform output control on the auxiliary braking force side, while in the case where the service brake uses air as the drive source, the service brake is With this configuration, output control on the main braking force side is performed.

That is, a differential pressure valve is provided in a drive air pipe for connecting a brake valve driven by a brake pedal and an air booster device for driving a wheel brake, and service is provided only when the supplied air pressure becomes high. While operating the brake, an electromagnetic switching valve is provided in the bypass air piping that connects the upstream side and the downstream side of the differential pressure valve in the drive air piping, and by driving this switching valve, the air pressure can be directly boosted by the air booster. It can be supplied to the device. In addition, an electromagnetic exhaust valve is provided in the exhaust air pipe connected to the drive air pipe, and the air is expelled from the air booster by appropriately driving this exhaust valve so that braking by the service brake is not performed. Or, the braking force is reduced. The ECU (electronic control unit) appropriately controls the switching valve and the exhaust valve to increase or decrease the operation amount of the service brake with respect to the depression amount (that is, the input) of the brake pedal to output on the main braking force side. It controls.

Further, in such a brake device with an auxiliary brake, the braking force of the service brake can be ensured even when the exhaust valve fails and is stuck in the open position.
A shutoff valve (safety valve) that operates with the air pressure supplied from the brake valve is provided in the exhaust air pipe, and the exhaust air pipe is shut off when the amount of depression of the brake pedal is large.

FIG. 5 shows a conventional shut-off valve provided in the exhaust air pipe. In this figure, 50 is a valve housing that forms the main body of the shutoff valve 47, a control port 52 is formed on the upper end, and a first input port 51a and an output port 53 are formed on the side surface. A second input port 51b is formed at the lower end. The control port 52 is connected to a brake valve (not shown) via an air pipe 48. Also,
The first and second input ports 51a and 51b are connected to an input port of an air booster (not shown) via air pipes 44a and 44b which communicate with each other. The output port 53 is connected to an exhaust valve (not shown) via the air pipe 45. On the other hand, in the valve housing 50, a control piston 56 and a valve body 57 that slide vertically are arranged, and return springs 58 and 59 that bias the control piston 56 and the valve body 57 upward, respectively. Is provided.

The shut-off valve 47 is in the state shown in FIG. 5 in a normal state (when not operating), and the first input port 5
The air flowing in from 1a passes through the communication hole 61 in the control piston 56 as shown by the arrow, and the output port 5
Flow to 3. Accordingly, the ECU (not shown) appropriately drives the exhaust valve to open, so that the air supplied to the air booster is exhausted, braking by the service brake is not performed, or the braking force is reduced. on the other hand,
FIG. 6 shows a state when the shutoff valve 47 is operating. That is, when the driver depresses the brake pedal, the air from the brake valve flows into the control port 52 via the air pipe 48. Then, when the differential pressure between the air pressure and the exhaust valve side pressure reaches a predetermined value (cut pressure), the control piston 56 overcomes the spring force of the return spring 58 and descends, and the lower end surface of the control piston 56 becomes the valve. Abut the body 57. As a result, even when the communication hole 61 is closed and the exhaust valve is fixed at the fully open position, the first
The communication between the input port 51a and the output port 53 is cut off to prevent the air from being exhausted, and as a result, the air pressure from the brake valve is directly supplied to the air booster.

[0009]

The conventional auxiliary brake combined type brake device has the following problems. In the shut-off valve 47 described above, when the exhaust valve is stuck at the fully open position, atmospheric pressure acts on the exhaust valve side of the control piston 56, so that the differential pressure between the air pressure and the atmospheric pressure reaches the cut pressure. Then, the shutoff valve 47 operates to block the exhaust of air. However, when the exhaust valve is stuck at the half open position or the small open position for some reason, the exhaust resistance does not allow the air to be smoothly discharged, and the back pressure acts on the output port 53. Like the return spring 58, this back pressure acts to urge the control piston 56 upward, and thus increases the above-mentioned cut pressure. as a result,
Even if the brake pedal is depressed, the shutoff valve 47 does not operate immediately, and the air is continuously exhausted from the air booster, which may deteriorate the effectiveness of the service brake. When the exhaust valve is stuck at the fully closed position, the exhaust is not performed irrespective of the operation of the shutoff valve 47, so such a problem does not occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an auxiliary brake-combined brake device in which the shut-off valve is reliably operated and the braking force is secured even when the exhaust valve fails. To aim.

[0011]

In order to achieve the above object, an auxiliary brake combined type brake device of the present invention comprises an auxiliary brake combined type brake device having an auxiliary brake in addition to a service brake operated by a brake pedal. The device is operated by a brake valve that regulates high-pressure air from an air tank according to the operation amount of a brake pedal, and high-pressure air supplied from the brake valve.
An air booster for driving a wheel brake of a vehicle, and a first connecting the brake valve and the air booster
The air booster is installed in the air passage and the first air passage, and only when the difference between the air pressure on the brake valve side and the air pressure on the air booster side exceeds a predetermined value, the air booster from the brake valve side A differential pressure valve that allows the high-pressure air to flow to the device side, a bypass air passage that communicates the upstream side and the downstream side of the differential pressure valve in the first air passage, and the first air passage is interposed in the bypass air passage. Between the switching valve that shuts off the bypass air passage at the position and connects the bypass air passage at the second position, and between the switching valve and the air booster,
The first air passage is connected to the first air passage through a second air passage,
Drive control of the exhaust valve, which opens the second air passage to exhaust high-pressure air from the air booster and shuts off the second air passage in the second position, and the bypass valve and the exhaust valve. Accordingly, the braking force control means for variably controlling the braking force on the service brake side and the third air passage, which is provided in the second air passage and upstream of the differential pressure valve in the first air passage, are provided. Connected, the second air passage is shut off when the air pressure supplied from the third air passage exceeds a predetermined value, and the second air passage is shut off by the air pressure on the exhaust valve side of the second air passage. And a shut-off valve having a control piston biased in the direction.

[0012]

In the brake device with auxiliary brake of the present invention, when the brake pedal is strongly depressed during sudden braking, air is supplied from the brake valve via the differential pressure valve even during operation of the auxiliary brake. The air booster is activated, and at the same time, the air from the brake valve is applied to the shutoff valve
The air is supplied through the air passage, and the exhaust passage from the air booster is blocked. At this time, when the air pressure on the exhaust valve side of the second air passage increases, the control piston is urged in the direction of blocking the pipeline of the second air passage. Therefore, when the exhaust valve is fixed at the half open position or the small open position and the back pressure acts on the exhaust port, the cut pressure decreases contrary to the conventional device, and the shut-off valve operates reliably by depressing the brake pedal.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a brake device with an auxiliary brake according to the present invention, which is mounted on a large rear engine bus (hereinafter simply referred to as a bus), will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a braking energy regeneration device 7 (auxiliary brake) of this embodiment. As shown in the figure, a through shaft differential unit 4 is connected to the front ends of the engine 1 and the transmission 2 which are vertically arranged, via a propeller shaft 3, and driving wheels 5 drive the engine 1. Transmit power.

A gear box 8 of a braking energy regeneration device 7 is connected to the front end of the differential unit 4 via a drive shaft 6. Then, when the differential carrier (that is, the drive wheels 5) not shown in the differential unit 4 rotates, the speed increasing gears 9 and 10 built in the gear box 8 also rotate.
A dog clutch 11 is built in the gear box 8, and the rotational force of the speed increasing gear 10 is transmitted to the swash plate type axial plunger type pump / motor 12 via the dog clutch 11.

The dog clutch 11 is drive-controlled by the ECU 13 to be in a connected or disconnected state. Further, the pump / motor 12 is also biased by a tilt cylinder (not shown) driven and controlled by the ECU 13 to change the tilt angle of the built-in swash plate 14, thereby changing the function between the pump and the motor and the discharge amount. Changes are made. The ECU 13 includes an accelerator sensor 15 for detecting an accelerator opening, a brake pressure sensor 16 for detecting a brake pressure, a vehicle speed sensor 17 for detecting a vehicle speed,
Various information is input from the pressure accumulation sensor 18 that detects the amount of accumulated pressure, the governor control unit 19 that controls the engine 1, and the like. The ECU 13 arithmetically processes these pieces of information to determine the operation mode of the braking energy regeneration device 7, and drive-controls the dog clutch 11, the pump / motor 12, and the like.

The pump / motor 12 is connected to a hydraulic oil tank 22 for storing hydraulic oil and a nitrogen gas filled type accumulator 23 via a low pressure pipe 20 and a high pressure pipe 21, respectively. An electromagnetic shutoff valve 24 is provided adjacent to the accumulator 23 in the pipeline of the high-pressure pipe 21. This shutoff valve 24 is normally used for the pump / motor 1
It operates as a check valve that allows the hydraulic oil to flow only from the 2 side to the accumulator 23 side, but when energized by the ECU 13, the hydraulic oil also flows from the accumulator 23 side to the pump / motor 12 side.

On the other hand, FIG. 2 shows a schematic structure of the service brake of this embodiment. This brake is an air-over-hydraulic brake, which drives an air master, which is an air booster, with high-pressure air to pressurize the brake fluid, and then supplies this to a wheel cylinder to drive the wheel brake. In the figure, 30 is a brake pedal 31.
An air tank 33, which is a high pressure air supply source, is connected to an input side of the brake valve via an air pipe 32. Further, the output side of the brake valve 30 has air pipes 34, 35, 3 forming the first air passage.
It is connected to the input side of the air master 37 via 6.
Further, the output side of the air master 37 is connected to a brake cylinder 40 in a wheel brake 39 via an oil pipe 38.
Connected to. Although only one set of the air master 37, the wheel brake 39, and the like are shown in FIG. 2, the air master 37 is provided for each brake system, and the wheel brake 39 is provided for each wheel.

A differential pressure valve 41 is interposed between the air pipes 34 and 35 so that the air pressure on the brake valve 30 side (that is, the upstream side) is the same as the air pressure on the air master 37 side (that is, the downstream side). Only when the difference exceeds a certain value,
Air is circulated from the upstream side to the downstream side. A bypass air pipe 42 is connected to the air pipe 34, bypasses the differential pressure valve 41, and supplies air from the brake valve 30 to the downstream side. An electromagnetic 3-port 2-position switching valve 43 is interposed between the air pipe 35, the bypass air pipe 42, and the air pipe 36.
The switching valve 43 is driven and controlled by the ECU 13, and in the first position in which the switching valve 43 is biased, the air pipe 35 and the air pipe 3 are urged.
6 is cut off to cut off the bypass air pipe 42, and at the deenergized second position (state shown in FIG. 2), the air pipe 35 is cut off to connect the bypass air pipe 42 and the air pipe 36. Let

An electromagnetic two-port two-position type exhaust valve 46 is connected to the air pipe 36 via air pipes 44 and 45 forming a second air passage. This exhaust valve 46 is E
Driven by the CU 13, the air pipe 45 is opened to the atmosphere at the urged first position, and the air pipe 45 is shut off at the deactivated second position (the state shown in FIG. 2). Further, a shutoff valve 47 is provided between the air pipes 44 and 45.
The air pipe 48, which is a third air passage connected to the air pipe 34, is connected to the shutoff valve 47.

As shown in FIG. 3, the shutoff valve 47 has an input port 51 formed at the upper end of the valve housing 50, a control port 52 and an output port 53 formed at the side surface, and a lower end. An exhaust port 54 is formed in the section. In the figure, 55 is a rubber exhaust cover. Control port 52 is air piping 3
It is connected to the brake valve 30 via 4, 48. Further, the input port 51 is connected to the air master 37 via the air pipes 36 and 44. The output port 53 is connected to the exhaust valve 46 via the air pipe 45.

In the valve housing 50, a control piston 56 that slides up and down and a rubber valve body 57 are arranged, and a return spring 58 that biases the control piston 56 upward and a valve body 57. And a return spring 59 for urging the lower part of the spring.
Further, a seat surface 60 against which the lower surface of the valve body 57 abuts is formed in the communication portion between the input port 51 and the output port 53, and a communication hole 61 communicating with the exhaust port 54 is formed in the axial center of the control piston. ing. In the state shown in FIG. 3, the valve body 57 and the seat surface 60 are not in contact with each other, and the upper opening of the communication hole 61 is closed by the valve body 57.

The operation of this embodiment will be described below. When a predetermined condition is satisfied during braking, the ECU 13 puts the braking energy regeneration device 7 in the braking mode in order to convert the braking energy into pressure energy. That is, the gear box 8
Drives the dog clutch 11 inside to drive the gear 10 and pump /
The motor 12 is connected, and at the same time, the tilt angle of the swash plate 14 in the pump / motor 12 is changed to function as a pump. Then, the differential carrier and the speed increasing gear 9,
The rotational force of the drive wheel 5 is transmitted via 10 to the pump /
The motor 12 rotates. As a result, the hydraulic oil tank 22
The hydraulic oil in the pump / motor 12 passes through the low-pressure pipe 20.
It is sucked and pressurized by and is pressure-fed to the accumulator 23 through the high-pressure pipe 21. The hydraulic oil sent under pressure is stored while compressing the nitrogen gas sealed in the accumulator 23, and is discharged from the accumulator 23 according to a command from the ECU 13 during start or acceleration mode. The discharged hydraulic oil drives the pump / motor 12 as a motor, assists in starting or accelerating, and then flows back to the hydraulic oil tank 22 via the low-pressure pipe 20.

On the other hand, the ECU 13 energizes the switching valve 43 and energizes the exhaust valve 46 when the auxiliary brake (braking energy regeneration device 7) is operating and the amount of depression of the brake pedal is small. . As a result, the air from the brake valve 30 is shut off by the differential pressure valve 41, while the air is exhausted from the air master 37, and the wheel brake 39 is deactivated or gently braked to prevent wear and heat generation of the brake shoes and the like. To be done. Further, in addition to the non-operation of the auxiliary brake, the switching valve 43 and the exhaust valve 46 are both deenergized when the amount of depression of the brake pedal is large even during the operation. As a result, the air from the brake valve 30 directly acts on the air master 37, and the wheel brake 39 operates. When sudden braking is performed during the operation of the auxiliary brake, air is supplied to the air master 37 via the differential pressure valve 41 while the switching valve 43 and the exhaust valve 46 are still energized, while the air is shut off. Exhaust valve 4 with valve 47 activated
Shut off the air passage to 6. Also in this case, the air from the brake valve 30 directly acts on the air master 37, and the wheel brake 39 operates.

Now, the ECU 13 controls the drive of the braking energy regeneration device 7 and simultaneously controls the service brake as follows. First, when the braking energy regeneration device 7 enters the braking mode, the ECU 13 energizes the switching valve 43 and simultaneously energizes the exhaust valve 46 at the same time. Then, the switching valve 4
The 3rd side is in the first position, the air pipe 35 and the air pipe 36 are communicated with each other, and the bypass air pipe 42 is cut off. The exhaust valve 46 side is also in the first position, and the air pipe 45 is opened to the atmosphere. At this time, the exhaust valve 4
If the urging of No. 6 is continuously performed, the air in the air master 37 is completely discharged, but if the urging is performed for a predetermined time (for example, 1 second), the discharge of air is stopped halfway.

In the braking mode, even if the driver depresses the brake pedal 31 shallowly, the air from the brake valve 30 is blocked from passing through the differential pressure valve 41, and at the same time, the air in the air master 37 passes through the air pipes 36, 44 and 45. It is exhausted from the exhaust valve 46 via the. Therefore, the air consumption is reduced, and the brake fluid in the brake cylinder 40 is also returned to the air master 37, so that the wheel brake 39 is not operated or is in the slow braking state. At this time, the shutoff valve 47
Air pressure from the brake valve 30 acts on the control port 52 of the vehicle through the air pipe 48. However, since the air pressure is equal to or lower than the cut pressure, the control piston 56 does not descend as shown in FIG. Therefore, the input port 51 and the output port 53 remain in the communication state, and the air flows toward the exhaust valve 46 side as indicated by the arrow in the figure.

On the other hand, in the braking mode, when the driver depresses the brake pedal 31 deeply and the air pressure from the brake valve 30 becomes higher than the set value of the differential pressure valve 41, the air passes through the differential pressure valve 41. At the same time, the shutoff valve 4
The control valve 52 of 7 has a brake valve 30
Air pressure exceeding the cut pressure from acts. Then, as shown in FIG. 4, the control piston 56 descends by overcoming the urging force of the return spring 58, and the valve element 57 urged by the return spring 59 moves the seat surface 60.
Abut. As a result, the input port 51 and the output port 53 are cut off, and the exhaust from the air master 37 is stopped. Therefore, the air that has passed through the differential pressure valve 41 is
It is supplied to the air master 37 via the air pipes 35 and 36 to drive the air master 37. Then, Air Master 3
7 pumps hydraulic fluid to the brake cylinder 40, and the wheel brake 39 operates. At this time,
The braking energy regeneration device 7 is also operating, and the vehicle is braked by both the braking energy regeneration device 7 and the wheel brake 39.

Now, as described above, when the exhaust valve 46 is fixed by a stick or the like at the half open or small open position,
Exhaust resistance prevents air from being discharged smoothly, and shutoff valve 4
Back pressure acts on the output port 53 of No. 7. However, in the shutoff valve 47 of the present embodiment, this back pressure acts so as to push down the control piston 56 when it is not operating as shown in FIG. Therefore, contrary to the conventional device, the cut pressure is reduced, and when the air from the brake valve 30 flows in from the control port 52, the control piston 56 descends relatively easily and the input port 5 moves.
1 and the output port 53 are cut off. As a result, the exhaust from the air master 37 is stopped, and the braking force by the wheel brake 39 is secured. Further, when the shutoff valve 47 operates, as shown in FIG.
Air from No. 3 communicates with the communication hole 61 of the control piston 56.
Through the exhaust port 54. for that reason,
The cutting pressure is determined only by the spring force of the return spring 58.

Although the description of the specific embodiment has been completed, the embodiment of the present invention is not limited to this embodiment. For example, although the present invention is applied to the air over hydraulic brake in the above embodiment, it may be applied to a full air brake using a brake chamber for an air booster. Further, as the auxiliary brake, a flywheel type or a power generation type braking energy regeneration device may be adopted, or an exhaust brake device or an electromagnetic retarder device may be adopted. Further, the switching valve and the exhaust valve may be air driven instead of the electromagnetic type. Further, the positional relationship of each port in the shutoff valve may be appropriately changed, and the shapes of the control piston and the valve element may be variously changed within the range in which the object of the present invention can be achieved.

[0029]

According to the present invention, since the above-described structure is adopted, the cut pressure of the shutoff valve does not increase even if the exhaust valve is stuck in the half open or small open position, and the braking force by the service brake is secured.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall configuration of an auxiliary brake according to the present invention.

FIG. 2 is a schematic diagram showing an overall configuration of a service brake according to the present invention.

FIG. 3 is a vertical cross-sectional view showing a non-operating state of the shutoff valve according to the present invention.

FIG. 4 is a vertical cross-sectional view showing a state of the shutoff valve according to the present invention during operation.

FIG. 5 is a vertical cross-sectional view showing a state in which a conventional shutoff valve is not operated.

FIG. 6 is a vertical cross-sectional view showing a state when a conventional shutoff valve is operating.

[Explanation of symbols]

 7 Braking Energy Regeneration Device 13 ECU 30 Brake Valve 31 Brake Pedal 33 Air Tank 34-36 Air Piping 37 Air Master 38 Oil Piping 39 Wheel Brake 40 Brake Cylinder 41 Differential Pressure Valve 42 Bypass Air Piping 43 Switching Valve 44, 45 Air Piping 46 Exhaust Valve 47 Shut-off valve 48 Air piping 51 Input port 52 Control port 53 Output port 54 Exhaust port 56 Control piston 57 Valve body 58, 59 Return spring 60 Seat surface 61 Communication hole

Claims (1)

[Claims] 1. A brake device with an auxiliary brake, which comprises an auxiliary brake in addition to a service brake actuated by a brake pedal, wherein the brake valve regulates high-pressure air from an air tank according to an operation amount of the brake pedal. An air booster that operates by high pressure air supplied from the brake valve to drive a wheel brake of the vehicle; a first air passage that connects the brake valve and the air booster; High pressure air from the brake valve side to the air booster side is installed only when the difference between the air pressure on the brake valve side and the air pressure on the air booster side is greater than a specified value by being installed in the air passage. A differential pressure valve that allows circulation, a bypass air passage that connects the upstream side and the downstream side of the differential pressure valve in the first air passage, and the bypass air passage A switching valve interposed between the switching valve and the air booster, the switching valve blocking the bypass air passage at the first position and communicating the bypass air passage at the second position; Connected to the air passage via the second air passage, opening the second air passage at the first position to exhaust high pressure air from the air booster, and shutting off the second air passage at the second position. An exhaust valve, a braking force control unit that variably controls the braking force on the service brake side by drivingly controlling the bypass valve and the exhaust valve, and the first air that is interposed in the second air passage. The second air passage is connected to the upstream side of the differential pressure valve in the passage via a third air passage, and shuts off the second air passage when the air pressure supplied from the third air passage exceeds a predetermined value. Depending on the air pressure on the exhaust valve side of the passage Auxiliary brake combination type brake device which is characterized in that comprises a shut-off valve having a control piston which is biased in a direction to block the second air passage.