JP2020101222A - Vehicle braking device - Google Patents

Abstract

To provide a vehicle braking device that can realize low cost and space saving of the device while ensuring relatively large braking force of an emergency brake and a life time of a brake pad in a vehicle.SOLUTION: A vehicle braking device comprises a first brake caliper that brakes a vehicle by contacting a first pad on a disc rotor, and a second brake caliper that brakes the vehicle by contacting a second pad on the disc rotor. The contact area of the second pad with the disc rotor is larger than the contact area of the first pad with the disc rotor, and the thickness of the second pad is thinner than the thickness of the first pad.SELECTED DRAWING: Figure 2

Description

The present invention relates to a braking device for a vehicle, and more particularly to a braking device that corresponds to a brake used in an emergency.

For example, in a vehicle such as a heavy-duty truck having a relatively large gross vehicle weight (GVW), it is possible to properly brake the vehicle even when the normally used disc brake cannot be used from the viewpoint of safety. It is necessary to mount a brake (Patent Document 1).

In particular, in electric trucks developed in recent years from the viewpoint of reducing the environmental load, regenerative braking using a driving motor is used because the engine brake does not operate. However, when traveling on a relatively long downhill on a highway or the like, the battery is fully charged by the regenerative electric power generated by the regenerative brake, and the regenerative brake cannot be used. Therefore, it is necessary to equip the electric truck with an emergency brake. ..

Since such an emergency brake is used infrequently, there is a demand for cost reduction and space saving from the viewpoint of manufacturing. Electric trucks are used less frequently, so there is a growing demand for space savings.

JP, 2003-341494, A

However, since a relatively large braking force is required during the operation of such an emergency brake, the size of the braking device that operates the emergency brake may increase. From the viewpoint of maintenance, it is required to extend the life of the brake pad.

The present invention has been made to solve such a problem, and its object is to reduce the cost of the device while ensuring a relatively large braking force of the emergency brake of the vehicle and the lifetime of the brake pad. -To provide a braking device for a vehicle that can save space.

A braking device for a vehicle according to this application example includes a first brake caliper that brakes a vehicle by contacting a first pad with a disk rotor, and a first brake caliper that contacts a second pad with the disk rotor. Two brake calipers, the contact area of the second pad with the disk rotor is larger than the contact area of the first pad with the disk rotor, and the thickness of the second pad is It is thinner than the thickness of the first pad.

In the vehicle braking device according to the application example described above, since the contact area of the second pad with respect to the disk rotor is set to be larger than the contact area of the first pad with respect to the disk rotor, the second pad is normally braked. It is possible to generate a braking force larger than that of the first pad used as, and it is possible to appropriately deal with it as a member for emergency braking of the vehicle.

The thickness of the second pad on the second brake caliper side is smaller than the thickness of the first pad on the first brake caliper side. That is, since it is used for emergency braking, the thickness of the second pad, which has a relatively small amount of wear, is small, and because it is used for normal braking, the thickness of the first pad, which has a relatively large amount of wear, is large. Therefore, the brake pad suitable for the brake use condition is set, and the lifetime of the brake pad itself is secured.

As described above, the vehicle braking device according to the above application example achieves cost reduction and space saving of the disc brake itself while ensuring a relatively large braking force of the vehicle emergency brake and a lifetime of the brake pad. be able to.

It is an upper surface figure showing roughly the whole electric vehicle carrying the brake equipment concerning the example of the present invention. It is a block diagram of the braking system comprised from the braking device concerning the example of the present invention. It is a partial perspective view of the braking device concerning the example of the present invention.

Embodiments of the present invention will be described in detail below with reference to the drawings.

First, an overall configuration of an electric vehicle 10 equipped with a braking device according to the present embodiment will be described with reference to FIG. Here, FIG. 1 is a top view schematically showing the overall configuration of the electric vehicle 10.

As shown in FIG. 1, the electric vehicle 10 is an electric truck (electric truck) including a ladder frame 11, a cab 12, a luggage box 13, a wheel mechanism 14, a drive device 15, a battery pack 16, and a drive power supply unit 17. is there. In addition, in FIG. 1, it is shown as a top view of the electric vehicle 10 as seen through the cab 12 and the luggage box 13.

In the present embodiment, the electric vehicle 10 is assumed to be an electric vehicle including a motor (electric motor) as a driving source for traveling, but may be a hybrid vehicle further including an engine. The electric vehicle 10 is not limited to the electric truck, and may be another commercial vehicle including a battery for driving the vehicle.

The ladder frame 11 has a left side rail 21L, a right side rail 21R, and a plurality of cross members 22. The left side rail 21L and the right side rail 21R extend in the vehicle length direction A of the electric vehicle 10 and are arranged parallel to each other in the vehicle width direction B. The plurality of cross members 22 connect the left side rail 21L and the right side rail 21R. The ladder frame 11 supports the cab 12, the luggage box 13, the driving device 15, the battery pack 16, and other heavy objects mounted on the electric vehicle 10. In the following, the left side rail 21L and the right side rail 21R are collectively referred to as the side rail 21.

The cab 12 is a structure including a driver's seat (not shown), and is provided above the front portion of the ladder frame 11. On the other hand, the luggage box 13 is a structure on which luggage or the like transported by the electric vehicle 10 is loaded, and is provided above the rear portion of the ladder frame 11.

In the present embodiment, the wheel mechanism 14 located in front of the vehicle includes left and right front wheels 23 located in front of the vehicle, and a front axle 24 as an axle of the two front wheels 23. Further, the wheel mechanism 14 located on the rear side of the vehicle includes rear wheels 25 located on the rear side of the vehicle and arranged two each on the left and right sides, and a rear axle 26 as an axle of these rear wheels 25. Then, in the electric vehicle 10, the driving force is transmitted so that the rear wheels 25 function as the driving wheels, and the electric vehicle 10 travels. The wheel mechanism 14 is suspended on the ladder frame 11 via a suspension mechanism (not shown) and supports the weight of the electric vehicle 10.

The drive device 15 includes a motor unit 31 and a gear unit 32. The motor unit 31 includes a motor and a motor housing that houses the motor. On the other hand, the gear unit 32 includes a reduction gear mechanism including a plurality of gears, a differential mechanism that distributes power input from the reduction gear mechanism to the left and right rear wheels 25, and a gear housing that accommodates these two mechanisms. To be done.

Further, the drive device 15 adjusts the drive torque of the motor by the reduction mechanism to a magnitude suitable for traveling of the vehicle, and transmits the driving force to the rear axle 26 via the reduction mechanism and the differential mechanism. As a result, the drive device 15 can rotate the rear wheels 25 via the rear axle 26 to drive the electric vehicle 10. Here, in the present embodiment, the drive device 15 is arranged inside the vehicle width direction B (that is, the space between the side rails) with respect to the left side rail 21L and the right side rail 21R, and is supported by a support member (not shown). It is supported by the ladder frame 11.

The battery pack 16 has a battery that supplies electric power to the motor of the drive device 15 as an energy source for running the electric vehicle 10, and a battery housing that houses the battery. The battery pack 16 is a relatively large-sized and large-capacity secondary battery for storing electric power required for the electric vehicle 10. In the present embodiment, the battery pack 16 is arranged between the left side rail 21L and the right side rail 21R in the vehicle width direction B and in front of the drive device 15 in the vehicle, but is limited to the arrangement location. There is no such thing. The battery pack 16 is fixed or suspended on the ladder frame 11 by a connecting member (not shown).

The drive power supply unit 17 is a so-called inverter, which converts the DC power supplied from the battery pack 16 into AC power and supplies the AC power to the motor. Then, the supply amount of the AC power is controlled according to the accelerator operation on the electric vehicle 10, and the rotation speed of the motor is controlled. In FIG. 1, the drive power supply unit 17 is provided on the vehicle rear side of the gear unit 32, but may be provided between the battery pack 16 and the drive device 15.

Next, the configuration of the braking system 40 mounted on the electric vehicle 10 and the disc brake 41 that is the braking device according to the present embodiment will be described with reference to FIGS. 2 and 3. Here, FIG. 2 is a block diagram of a braking system mounted on the electric vehicle 10. FIG. 3 is a partial perspective view of the disc brake 41.

As shown in FIG. 2, the braking system 40 includes a disc brake 41, two hydraulic pressure adjusting units (a first hydraulic pressure adjusting unit 42 and a second hydraulic pressure adjusting unit 43), a brake pedal 44, an emergency brake switch 45, and an ECU 46. doing. In the braking system 40, a brake pedal 44 (so-called foot brake) is used as a normal brake operation, and a larger braking force that does not function normally or causes an emergency stop of the vehicle is applied. The emergency brake switch 45 is used for.

In the braking system 40, a disc brake 41 is provided on each wheel (front wheel 23, rear wheel 25) so that a braking force can be applied to all the wheels of the electric vehicle 10 at the same time. The disc brake 41 of each wheel includes one disc rotor 51 rotating with the wheel and two brake calipers (first brake caliper 52 and second brake caliper 53).

The first brake caliper 52 is connected to the first hydraulic pressure adjustment unit 42 via a first oil pipe 54. The first brake caliper 52 includes a first pad 57 including two brake pads (an inner pad 55 and an outer pad 56 ), and a first piston 58 that presses the first pad 57 against the disc rotor 51 using hydraulic pressure. Is included. The detailed structure of the disc brake 41 will be described later with reference to FIG.

The first hydraulic pressure adjustment unit 42 is composed of, for example, a brake booster and a master cylinder. The brake booster has a function of increasing the depression force (depression amount) with respect to the brake pedal 44 at a constant rate. Further, the master cylinder has a function of converting the increased force into hydraulic pressure.

In the present embodiment, the first brake caliper 52 operates in response to the operation of the brake pedal 44, and applies a normal braking force to each wheel during traveling and when the vehicle is stopped. Specifically, when the driver operates the brake pedal 44, the hydraulic pressure in the first oil pipe 54 is adjusted by the first hydraulic pressure adjusting unit 42 to a desired hydraulic pressure corresponding to the depression amount of the brake pedal 44. Then, the hydraulic pressure causes the first piston 58 to bring the first pad 57 into contact with the disc rotor 51, whereby a desired braking force is applied to each wheel.

Note that, in FIG. 2, one first brake caliper 52 is connected to the first hydraulic pressure adjusting unit 42 via the first oil pipe 54, but in reality, the first hydraulic pressure adjusting unit 42 includes wheels. Are connected to a plurality of first brake calipers 52. Then, the first hydraulic pressure adjusting unit 42 adjusts the hydraulic pressure in the first oil pipe 54 so that the first brake calipers 52 of the respective wheels operate simultaneously. That is, the first hydraulic pressure adjustment unit 42 controls the operation of the disc brake 41 provided on each wheel of the electric vehicle 10.

On the other hand, the second brake caliper 53 is connected to the second hydraulic pressure adjustment unit 43 via the second oil pipe 61. The second brake caliper 53, like the first brake caliper 52, also has a second pad 64 composed of two brake pads (the inner pad 62 and the outer pad 63) and a disk for the second pad 64 using hydraulic pressure. It includes a second piston 65 that is pressed against the rotor 51.

The second hydraulic pressure adjustment unit 43 is connected to the ECU 46 and adjusts the hydraulic pressure in the second oil pipe 61 to a desired hydraulic pressure according to a control signal supplied from the ECU 46. Here, the desired hydraulic pressure has a constant pressure value that can apply a braking force larger than the above-described normal braking force to the wheels to urgently decelerate or stop the electric vehicle 10.

With such a configuration, the second brake caliper 53 operates in response to the pressing of the emergency brake switch 45, and applies a large braking force for emergency response during running and stopping to each wheel. Specifically, when the driver determines that it is an emergency, when the emergency brake switch 45 is pressed, the ECU 46 recognizes that the emergency brake is necessary, the ECU 46 drives and controls the second hydraulic pressure adjustment unit 43, and the second oil The hydraulic pressure in the pipe 61 is adjusted to a desired hydraulic pressure by the second hydraulic pressure adjusting unit 43. Then, the second piston 65 brings the second pad 64 into contact with the disk rotor 51 by the hydraulic pressure, whereby a desired braking force in an emergency is applied to the wheel.

Note that, in FIG. 2, one second brake caliper 53 is connected to the second hydraulic pressure adjusting unit 43 via the second oil pipe 61, but like the first brake caliper 52 side, the second hydraulic pressure adjusting part 43 is adjusted. A plurality of second brake calipers 53 provided on each wheel are connected to the portion 43. Then, the second hydraulic pressure adjusting unit 43 adjusts the hydraulic pressure in the second oil pipe 61 so that the second brake calipers 53 of the respective wheels operate simultaneously.

As a more detailed structure of the disc brake 41, as shown in FIG. 3, the disc brake 41 includes a disc rotor 51 that rotates integrally with wheels, and a disc rotor 51 fixed to the vehicle body at one side of the disc rotor 51. A torque member 71, which is arranged so as to straddle a part of the disc 51, and a disc rotor 51, are arranged so as to be slidable in the axial direction of the disc rotor 51 with respect to the torque member 71 by a slide pin 72. And a first brake caliper 52. Although not shown in FIG. 3, the second brake caliper 53 and the second brake caliper 53 for the second brake caliper 53 are provided at a position (for example, the opposite side opposite to) where the first brake caliper 52 and the torque member 71 are installed. A torque member and slide pin are also provided.

A pair of inner pad 55 and outer pad 56 are arranged on the torque member 71 so as to sandwich the disc rotor 51. These pads are held in a state of being fitted in the groove formed in the torque member 71, and are slidable in the axial direction of the disc rotor 51.

A first piston 58 is inserted on one side of the first brake caliper 52 that sandwiches the disc rotor 51. The first piston 58 and the first brake caliper 52 slide relative to each other and move relative to each other. It is configured to be possible. The inner pad 55 is arranged between the first piston 58 and the disc rotor 51. Similarly, an outer pad 56 is arranged between the disc rotor 51 and a claw (not shown) of the first brake caliper 52 located on the other side of the disc rotor 51.

Although not shown in FIG. 3, the torque member for the second brake caliper 53, the disc rotor 51, the inner pad 62, the outer pad 63, and the second piston 65 also have the same arrangement and sliding structure. Has been done.

Then, during braking, hydraulic pressure is applied to a hydraulic chamber (not shown) of the first piston 58, which pushes the first piston 58, and the tip portion thereof pushes the inner pad 55 against the disc rotor 51. On the other hand, the claw located on the other side of the first brake caliper 52 sandwiching the disc rotor 51 is formed integrally with the one side, and when the hydraulic pressure is applied to the hydraulic chamber, the reaction force applied to the one side causes the other side. The side claws are attracted to the outer pad 56, and the outer pad 56 is pressed against the disc rotor 51. Due to these actions, the disc rotor 51 is sandwiched by the inner pad 55 and the outer pad 56 from both sides, and a braking force is generated. Since the same operation is realized by the same structure on the second brake caliper 53 side, the description thereof will be omitted.

Here, in the present embodiment, the difference between the structure on the first brake caliper 52 side and the structure on the second brake caliper 53 side is that the contact area of the second pad 64 with respect to the disk rotor 51 is as shown in FIG. Is set larger than the contact area of the first pad 57 with respect to the disc rotor 51. With such a configuration, the second pad 64 can generate a larger braking force than the first pad 57 that is normally used as a brake, and can appropriately serve as a member for emergency braking of the electric vehicle 10. it can.

The initial (before use) thickness of the second pad 64 of the second brake caliper 53 is smaller than the initial (before use) thickness of the first pad 57 on the first brake caliper 52 side. That is, since it is used for emergency braking, the thickness of the second pad 64 with a relatively small amount of wear is reduced, and since it is used for normal braking, the thickness of the first pad 57 with a relatively large amount of wear is used. Is getting bigger. With such a configuration, a brake pad suitable for the brake use condition is set, and the lifetime of the brake pad itself is secured.

As described above, the disc brake 41, which is the braking device of the electric vehicle 10 according to the present embodiment, ensures the relatively large braking force of the emergency brake of the electric vehicle 10 and the lifetime of the brake pad, while the disc brake 41 itself. It is possible to achieve cost reduction and space saving.

In this embodiment, the structure for emergency braking (the second brake caliper 53, the torque member for the second brake caliper 53, the inner pad 62, the outer pad 63, the second piston 65) is provided on all the wheels. However, if the required emergency stop or deceleration of the electric vehicle can be realized, the wheels provided with the structure may be appropriately selected. For example, it may be provided on either the front wheel or the rear wheel, or may be a part of the rear wheel.

10 Electric Vehicle 11 Ladder Frame 12 Cab 13 Packing Box 14 Wheel Mechanism 15 Drive Device 16 Battery Pack 17 Drive Power Supply Section 40 Braking System 41 Disc Brake (Brake Device)
42 1st oil pressure adjustment part 43 2nd oil pressure adjustment part 44 Brake pedal 45 Emergency brake switch 46 ECU
51 disc rotor 52 first brake caliper 53 second brake caliper 54 first oil pipe 55, 62 inner pad 56, 63 outer pad 57 first pad 58 first piston 61 second oil pipe 64 second pad 65 second piston A vehicle Long direction B Vehicle width direction

Claims (1)

A first brake caliper for braking the vehicle by bringing the first pad into contact with the disc rotor;
A second brake caliper for braking the vehicle by bringing a second pad into contact with the disc rotor,
The contact area of the second pad with the disk rotor is larger than the contact area of the first pad with the disk rotor, and the thickness of the second pad is larger than the thickness of the first pad. Braking device for thin vehicles.

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