JP3141657B2 - Brake device with auxiliary brake - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake device combined with an auxiliary brake used 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]

2. Description of the Related Art In general, friction brakes such as a drum brake and a disc brake operated by a brake pedal are used as service brakes for automobiles. However, with a friction brake, a fade phenomenon and a vapor lock phenomenon occur when frequent use is performed on a long downhill, and the brake shoes and brake pads are also worn. Running costs also tended to be high. Also, friction brakes convert kinetic energy into heat and release it to the atmosphere during braking, so in the case of route buses that frequently start and stop,
There was a problem from the viewpoint of energy saving.

Therefore, in large vehicles such as buses and trucks, as an auxiliary brake for assisting braking by a service brake, an exhaust brake or a braking energy regenerating device that collects kinetic energy and uses it at the time of starting or accelerating is used. It has been used for some time. Although there are flywheel type and power generation type in the braking energy regenerating device,
The pressure accumulating type described in Japanese Patent Application Laid-Open No. 64900, Japanese Patent Publication No. Hei 5-1168 or the like is predominant in terms of performance and cost. In this braking energy regenerating apparatus, a hydraulic pump / motor is 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 during braking of the vehicle to pump hydraulic oil in the hydraulic oil tank to the accumulator. 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.

[0004] For example, in a braking device using this kind of braking energy regenerating device (auxiliary brake) together, the contribution ratio between the service brake and the auxiliary brake during braking is appropriately changed based on the accumulated pressure of the accumulator and the vehicle speed. I have. In order to perform such control, the auxiliary brake is provided with various hydraulic control solenoid valves or the like to perform output control on the auxiliary braking force side. On the other hand, if the service brake uses air as a drive source, Thus, the output control on the main braking force side is performed.

That is, a differential pressure valve is provided in a driving air pipe connecting a brake valve driven by a brake pedal and an air booster for driving a wheel brake, and a service is provided only when the supplied air pressure becomes high. While the brake is operated, an electromagnetic switching valve is provided in the bypass air piping that connects the upstream and downstream sides of the differential pressure valve in the driving air piping, and by driving this switching valve, the air pressure is directly increased by air. It can be supplied to the equipment. Also, an electromagnetic exhaust valve is provided in the exhaust air pipe connected to the driving air pipe, and the exhaust valve is driven appropriately to exhaust air from the air booster so that braking by the service brake is not performed. Or reducing its braking force. The switching valve and the exhaust valve are appropriately driven and controlled by an ECU (Electronic Control Unit) to increase or decrease the operation amount of the service brake with respect to the depression amount (that is, input) of the brake pedal, and output the main braking force. It controls.

Further, in such a brake device with an auxiliary brake, even if the exhaust valve fails and is stuck at the open position, the braking force of the service brake can be secured.
A shutoff valve (safety valve) that is operated by 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 depression amount of the brake pedal is large.

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

The shut-off valve 47 is normally in the state shown in FIG.
As shown by an arrow, the air flowing from the output port 5a flows through the communication hole 61 in the control piston 56.
Flow to 3. Accordingly, when the ECU (not shown) appropriately drives the exhaust valve to open, the air supplied to the air booster is exhausted, and the 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 shut-off valve 47 is operated. That is, when the driver depresses the brake pedal, air from the brake valve flows into the control port 52 via the air pipe 48. When the pressure difference 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. Abuts body 57. Thereby, even when the communication hole 61 is closed and the exhaust valve is stuck 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 exhaust of air, and as a result, the air booster is directly supplied with air pressure from the brake valve.

[0009]

The conventional brake device combined with an auxiliary brake has the following problems. In the shut-off valve 47 described above, when the exhaust valve is stuck at the fully open position, the 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 shut-off valve 47 operates to prevent the exhaust of the air. However, if the exhaust valve is stuck at the half-open position or the small-open position for some reason, air is not smoothly discharged due to exhaust resistance, and back pressure acts on the output port 53. This back pressure acts to urge the control piston 56 upward, similarly to the return spring 58, and thus increases the above-described cut pressure. as a result,
Even if the brake pedal is depressed, the shut-off valve 47 does not operate immediately, and the air is continuously exhausted from the air booster, so that the service brake may be less effective. When the exhaust valve is stuck at the fully closed position, no exhaust is performed irrespective of the operation of the shut-off valve 47, so that such a problem does not occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides an auxiliary brake combined type brake device in which a shut-off valve is reliably operated even in the event of a failure of an exhaust valve to secure a braking force. Aim.

[0011]

In order to achieve the above object, an auxiliary brake combined use brake device of the present invention comprises an auxiliary brake combined use brake provided with an auxiliary brake in addition to a service brake operated by a brake pedal. A brake valve that regulates high-pressure air from an air tank according to an operation amount of a brake pedal, and is operated by 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.
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 or equal to a predetermined value, is the air booster interposed between the air passage and the first air passage. wherein a differential pressure valve which allows the flow of high-pressure air 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 brake valve
Provided between the air booster and the brake valve
These high-pressure air to the air booster via the differential pressure valve
A first position that can be supplied;
Can be supplied to the air booster via the Ipass air passage
A switching valve switched between a second position and a switching valve connected between the switching valve and the air booster via a second air passage to the first air passage; (2) Opening the air passage to exhaust high-pressure air from the air booster, and controlling the drive of the exhaust valve that shuts off the second air passage at the second position, and the switching valve and the exhaust valve, Braking force control means for variably controlling a braking force on a service brake side; and a brake force control means interposed in the second air passage closer to the first air passage than the exhaust valve and in the first air passage. An upstream side of the differential pressure valve is connected via a third air passage. When the air pressure supplied from the third air passage becomes equal to or higher than a predetermined value, the second air passage is shut off, and exhaust of the second air passage is performed. Energized in the direction to shut off the second air passage by the air pressure on the valve side Characterized in that comprising a shut-off valve having that control piston.

[0012]

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

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a brake device with an auxiliary brake according to the present invention mounted on a large rear engine bus (hereinafter simply referred to as a bus). FIG. 1 shows a schematic configuration of a braking energy regeneration device 7 (auxiliary brake) of the present embodiment. As shown in FIG. 1, a through-shaft type differential unit 4 is connected to front ends of an engine 1 and a transmission 2 which are vertically arranged via a propeller shaft 3. Transmit power.

A gear box 8 of a braking energy regenerating device 7 is connected to a front end of the differential unit 4 via a drive shaft 6. Then, when a differential carrier (that is, the drive wheel 5) (not shown) rotates in the differential unit 4, the speed increasing gears 9 and 10 built in the gear box 8 also rotate.
Further, 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 driven and controlled by the ECU 13 to enter a connected or disconnected state. Further, the pump / motor 12 is also urged 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 switching the function between the pump and the motor and changing 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 types of information are input from a pressure accumulation sensor 18 that detects the amount of accumulated pressure, a governor control unit 19 that controls the engine 1, and the like. The ECU 13 performs arithmetic processing on these pieces of information to determine the operation mode of the braking energy regeneration device 7, and controls the driving of the dog clutch 11, the pump / motor 12, and the like.

The pump / motor 12 is connected via a low-pressure pipe 20 and a high-pressure pipe 21 to a hydraulic oil tank 22 for storing hydraulic oil and a nitrogen gas-filled accumulator 23, respectively. An electromagnetic shutoff valve 24 is provided in the pipeline of the high-pressure pipe 21 adjacent to the accumulator 23. The shut-off valve 24 normally operates the pump / motor 1
It operates as a check valve that allows the hydraulic oil to flow only from the second 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 configuration of the service brake of the present 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 sends it to a wheel cylinder to drive the wheel brake. In the figure, 30 is a brake pedal 31
An air tank 33 serving as a high-pressure air supply source is connected to an input side of the brake valve via an air pipe 32. The output side of the brake valve 30 is connected to air pipes 34, 35, 3 that constitute a first air passage.
6 is connected to the input side of the air master 37.
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 and the wheel brake 39 is shown in FIG. 2, the air master 37 is provided for each brake system, and the wheel brake 39 is provided for each wheel.

[0018] Between the air pipe 34, 35 is interposed the differential pressure valve 41, the brake valve 30 side (i.e., upstream) air pressure and Eamasuta 37 side (i.e., downstream side) of the air pressure Only when the difference is greater than or equal to the predetermined value,
Air flows from the upstream side to the downstream side. Further, a bypass air pipe 42 is connected to the air pipe 34, and bypasses the differential pressure valve 41 to supply air from the brake valve 30 to the downstream side. An electromagnetic three-port two-position switching valve 43 is interposed between the air pipe 35 and the bypass air pipe 42 and the air pipe 36.
The switching valve 43 is driven and controlled by the ECU 13 so that the air pipe 35 and the air pipe 3
6, the bypass air pipe 42 is shut off, and in the deenergized second position (the state shown in FIG. 2), the air pipe 35 is shut off to connect the bypass air pipe 42 and the air pipe 36. Let it.

The air pipe 36 is connected to an electromagnetic two-port two-position exhaust valve 46 via air pipes 44 and 45 constituting 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 first position that is energized, and is shut off at the second position that is deenergized (the state shown in FIG. 2). A shut-off valve 47 is provided between the air pipes 44 and 45.
An air pipe 48, which is a third air passage connected to the air pipe 34, is connected to the shut-off valve 47.

As shown in FIG. 3, the shut-off 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, and a lower end. An exhaust port 54 is formed in the portion. In the figure, reference numeral 55 denotes an exhaust cover made of rubber. The control port 52 is connected to the air pipe 3
It is connected to the brake valve 30 via 4,48. 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.

A control piston 56 which slides up and down and a rubber valve body 57 are disposed in the valve housing 50, and a return spring 58 which urges the control piston 56 upward, and a valve body 57. And a return spring 59 for urging the downward.
In addition, a communication surface between the input port 51 and the output port 53 has a seat surface 60 with which the lower surface of the valve body 57 contacts, and a communication hole 61 that communicates with the exhaust port 54 is formed in the axis of the control piston. ing. In the state shown in FIG. 3, the valve body 57 does not contact the seat surface 60, 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 at the time of braking, the ECU 13 puts the braking energy regenerating device 7 into the braking mode in order to convert the braking energy into the pressure energy. That is, the gear box 8
Drive the dog clutch 11 to connect the speed-increasing gear 10 to the pump / motor 12,
The tilt angle of the inner swash plate 14 is changed to function as a pump. Then, the rotational force of the drive wheel 5 is transmitted via the differential carrier and the speed increasing gears 9 and 10, and the pump / motor 12 rotates. Thereby, the hydraulic oil in the hydraulic oil tank 22 is sucked and pressurized by the pump / motor 12 via the low-pressure pipe 20, and the high-pressure pipe 21 and the shut-off valve 2
4 to the accumulator 23. The pumped hydraulic oil is stored while compressing the nitrogen gas sealed in the accumulator 23, and is discharged from the accumulator 23 in response to a command from the ECU 13 in the start or acceleration mode. The released hydraulic oil drives the pump / motor 12 as a motor and assists starting or accelerating.
The liquid is returned to the hydraulic oil tank 22 through the low-pressure pipe 20.

On the other hand, when the auxiliary brake (braking energy regeneration device 7) is operating and the depression amount of the brake pedal is small, the ECU 13 activates the switching valve 43 and also appropriately activates the exhaust valve 46. . Thereby, while the air from the brake valve 30 is shut off by the differential pressure valve 41, the air is exhausted from the air master 37, and the wheel brake 39 is inactivated or slowly braked, thereby preventing wear and heat generation of the brake shoes and the like. Is done. In addition, when the depression amount of the brake pedal is large even when the auxiliary brake is inactive or in operation, the switching valve 43 and the exhaust valve 46 are both deenergized. 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 kept energized. The valve 47 is operated and the exhaust valve 4
6. 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 is operated.

The ECU 13 simultaneously controls the driving of the braking energy regeneration device 7 and controls the driving of the service brake as follows. First, when the braking energy regeneration device 7 enters the braking mode, the ECU 13 activates the switching valve 43 and simultaneously activates the exhaust valve 46 as appropriate. Then, the switching valve 4
The third side is in the first position, the air pipe 35 and the air pipe 36 are communicated, and the bypass air pipe 42 is shut off. Further, the exhaust valve 46 is also at the first position, and the air pipe 45 is opened to the atmosphere. At this time, the exhaust valve 4
If the biasing of step 6 is continued, the air in the air master 37 is completely discharged. However, if the pressing is performed for a predetermined time (for example, one second), the discharge of the air stops halfway.

In the braking mode, even if the driver steps on the brake pedal 31 shallowly, the air from the brake valve 30 is prevented from passing through the differential pressure valve 41, and at the same time, the air in the air master 37 flows through the air pipes 36, 44, 45. The air is exhausted from the exhaust valve 46 via the exhaust valve 46. Accordingly, the amount of 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 slowly braked. At this time, the shutoff valve 47
The air pressure from the brake valve 30 acts on the control port 52 via the air pipe 48. However, since the air pressure is 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 communication with each other, and air flows toward the exhaust valve 46 as shown 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 shut-off valve 4
7 has a brake valve 30
Air pressure exceeding the cut pressure from the air 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 body 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 shut off, and the exhaust from the air master 37 is not performed. Therefore, the air that has passed through the differential pressure valve 41
The air is supplied to the air master 37 via the air pipes 35 and 36 to drive the air master 37. Then, Air Master 3
Reference numeral 7 indicates that the hydraulic oil is pressure-fed to the brake cylinder 40, and the wheel brake 39 is operated. In this case,
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.

As described above, when the exhaust valve 46 is fixed at a half-open position or a slightly open position by a stick or the like,
Air is not discharged smoothly due to exhaust resistance, and the shutoff valve 4
7, a back pressure acts on the output port 53. However, in the shut-off valve 47 of the present embodiment, the back pressure acts so as to push down the control piston 56 when not operating as shown in FIG. Therefore, contrary to the conventional device, the cut pressure decreases, and when 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
1 and the output port 53 are shut off. As a result, the exhaust from the air master 37 is not performed, and the braking force by the wheel brake 39 is secured. Further, when the shut-off valve 47 is operated, as shown in FIG.
3 from the communication hole 61 of the control piston 56
The air is exhausted from the exhaust port 54 via the 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 above, embodiments of the present invention are not limited to this embodiment. For example, in the above embodiment, the present invention is applied to an air over hydraulic brake, but may be applied to a full air brake or the like using a brake chamber in an air booster. Further, a braking energy regenerating device such as a flywheel type or a power generation type may be employed as the auxiliary brake, or an exhaust braking device or an electromagnetic retarder device may be employed. Further, the switching valve and the exhaust valve may be of an air-driven type instead of the electromagnetic type. Further, the positional relationship between the ports in the shutoff valve may be changed as appropriate, and the shapes of the control piston and the valve body may be variously changed as long as the object of the present invention can be achieved.

[0029]

According to the present invention, since the above-described configuration is employed, the cut pressure of the shut-off valve does not increase even if the exhaust valve is stuck at the half-open or small-open position, and the braking force by the service brake is secured.

[Brief description of the 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 entire configuration of a service brake according to the present invention.

FIG. 3 is a longitudinal sectional view showing a state where the shut-off valve according to the present invention is not operated.

FIG. 4 is a longitudinal sectional view showing a state when the shut-off valve according to the present invention is operated.

FIG. 5 is a longitudinal sectional view showing a state where a conventional shut-off valve is not operated.

FIG. 6 is a longitudinal sectional view showing a state when a conventional shut-off valve is operated.

[Explanation of symbols]

 7 Brake energy regeneration device 13 ECU 30 Brake valve 31 Brake pedal 33 Air tank 34 to 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 element 58, 59 Return spring 60 Seat surface 61 Communication hole

Claims (1)

(57) [Claims] An auxiliary brake combined type brake device provided with an auxiliary brake in addition to a service brake operated by a brake pedal, wherein the brake valve regulates high-pressure air from an air tank in accordance with an operation amount of the brake pedal. An air booster that operates by high-pressure air supplied from the brake valve and drives a wheel brake of a vehicle; a first air passage connecting the brake valve and the air booster; Only when the difference between the air pressure on the brake valve side and the air pressure on the air booster exceeds a predetermined value, the high-pressure air from the brake valve side to the air booster side is interposed in the air passage. a differential pressure valve which allows the flow, and bypass air passage communicating the upstream side and the downstream side of the differential pressure valve in the first air passage, the brake valve and the front Et provided between the air booster
The high pressure air from the brake valve to the differential pressure valve.
First position that can be supplied to the air booster via
And the high pressure air is passed through the bypass air passage.
Switch to the second position that can be supplied to the air booster
A switching valve to be replaced, connected between the switching valve and the air booster via a second air passage to the first air passage, and opening the second air passage at a first position to open the second air passage. An exhaust valve that exhausts high-pressure air from the air booster and shuts off the second air passage at the second position; and by driving-controlling the switching valve and the exhaust valve,
Braking force control means for variably controlling a braking force on a service brake side; and being interposed in the second air passage closer to the first air passage than the exhaust valve and upstream of the differential pressure valve in the first air passage. The third air passage is connected to the second air passage when the air pressure supplied from the third air passage becomes equal to or higher than a predetermined value. And a shut-off valve having a control piston which is urged in a direction to shut off the second air passage by pressure.