JPH11189131A - Brake device for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To moderate a longitudinal directional attitude change in a vehicle, and restrain an unpleasant feeling of an occupant by arranging a damping force generating mechanism to slow down a release of a brake in a brake pedal or a braking booster of a brake device for an automobile. SOLUTION: When a foot is released in a stepping position of a brake pedal 5 required to decelerate a vehicle, the brake pedal 5 tries to return to a former position by tensile force of a return spring 9 and fluid pressure of a master cylinder 8. A brake damper 6 slowly extends, the brake pedal 5 also slowly returns to the former position side according to this, an operating rod 12 of a braking booster 7 is pulled, and oil pressure generated in the master cylinder 8 gradually reduces to release wheel side braking force. An unpleasant feeling of an occupant can be restrained by restraining backward acceleration of a vehicle at braking time from suddenly changing in the forward direction of the vehicle by gradually releasing a brake.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake apparatus for an automobile for improving an uncomfortable forward and backward swing of a vehicle, which is caused by releasing a brake.

[0002]

2. Description of the Related Art FIG. 10 is a diagram for explaining a change in behavior of a conventional vehicle before and after braking. The acceleration acting on the vehicle and the posture of the vehicle from before braking to after braking are compared with the braking force, the front wheel contact load and the occupant. Shown together with the acting inertial force. The horizontal axis represents time. The state of the vehicle will be described below. ~
Is described in the vehicle model. The vehicle 1 is traveling at a constant speed.

[0003] Here, braking is started (starting to depress the brake). The braking force is generated by the brake device, and the vehicle 1 is decelerated. Accordingly, a rearward acceleration is generated in the vehicle 1, and an inertial force is generated in the vehicle 1 in a direction opposite to the direction of the acceleration (forward). Therefore, the vehicle 1 leans forward,
Front wheel contact load increases. At this time, the inertia force acts on the occupant in the same direction (forward) as the vehicle 1.

When the vehicle speed has decreased to a desired speed, the driver releases his / her foot from the brake pedal to release the braking. The sudden decrease in the braking force causes the acceleration acting on the vehicle 1 to suddenly change to the forward direction. As a result, an inertial force is generated in the vehicle 1 in a direction opposite to the direction of the acceleration (rearward direction), and the suspension of the contracted front wheel is rapidly extended, and the vehicle 1 is in a front-up state, and the front wheel is in contact with the front wheel. The load decreases temporarily. At this time, an inertial force is generated in the occupant in the same direction (backward) as the vehicle 1. The vehicle 1 returns to a substantially horizontal posture.

[0005]

In the above prior art, when the foot is released from the brake pedal, the brake pedal quickly returns to the original position, and the braking force is immediately released. Therefore,
As shown in FIG. 10, the vehicle 1 suddenly shifts from a forward leaning posture to a forward rising posture. That is, when the braking force is released, the vehicle 1 suddenly swings in the front-rear direction, and the occupant feels discomfort. Therefore, an object of the present invention is to provide an automobile brake device that can moderate a change in the posture of the vehicle 1 in the front-rear direction by slowing the release of the braking, thereby suppressing occupant discomfort.

[0006]

In order to achieve the above object, a first aspect of the present invention is to provide a brake pedal or a brake booster which constitutes an automobile brake device, a damping force generating mechanism for slowing release of a brake. Was provided. The damping force generating mechanism gradually releases the brake, and suppresses a sudden change of the vehicle rearward acceleration at the time of braking to the vehicle forward direction.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of reference numerals. FIG. 1 is a side view showing a pedal portion of a vehicle brake device according to the present invention. A vehicle brake device 3 provided on a vehicle body 2 of the vehicle has a brake pedal rotatably mounted on a shaft 4 connected to the vehicle body 2. 5, a brake damper 6 provided as a damping force generating mechanism provided between the brake pedal 5 and the vehicle body 2, a brake booster 7 for increasing the stepping force when the brake pedal 5 is depressed, and the brake booster It comprises a master cylinder 8 for converting the pedaling force into a hydraulic pressure via 7 and transmitting the hydraulic pressure to wheels (not shown), and a return spring 9 for returning the brake pedal 5 to its original position when the brake pedal 5 is released from being depressed. In addition, 12 is the brake booster 7
And a member connected to the brake pedal 5. Reference numeral 13 denotes a spring support member provided on the vehicle body 2.

FIG. 2 is a graph showing the characteristics of the brake damper according to the present invention, wherein the vertical axis represents the damping force, and the upward stroke of the brake damper and the downward stroke of the brake damper. The horizontal axis represents the speed of the piston of the brake damper. In the extension stroke, as shown in the figure, the damping force increases as the piston speed increases. Further, in the contraction stroke, almost no damping force is generated as shown in the figure. Next, the structure of a brake damper exhibiting such characteristics will be described.

FIG. 3 is a sectional view of a brake damper according to the present invention. The brake damper 6 has a cylinder 21, a piston 22 and a free piston 23 slidably inserted into the cylinder 21, and attached to the piston 22. And a rod guide 25 for supporting the piston rod 24. In addition, brake damper 6
The outer oil chamber A and the inner oil chamber B, which are defined by a piston 22 in the cylinder 21, and the cylinder 21
And a gas chamber C partitioned from an inner oil chamber B.

Here, 24a is a brake pedal mounting portion of the piston rod 24, 25a is an O-ring for sealing between the rod guide 25 and the piston rod 24, and 25b is an O-ring for sealing between the rod guide 25 and the cylinder 21.
26, an O-ring for sealing between the cylinder 21 and the vehicle body mounting portion 26; 27, an outer peripheral groove of the free piston 23 for sealing between the inner oil chamber B and the gas chamber C; This is an O-ring provided on 23a.

The piston 22 includes a piston body 28, a check valve 31 provided on the outer oil chamber A side of the piston body 28, and the check valve 31
A spring 3 for pressing against the piston 8 and an extension valve 3 provided on the oil chamber B side of the piston body 28.
3 In addition, 34 is a washer and 35 is a nut, and the washer 34 and the nut 35 fix the piston 22 to the piston rod 24.

The piston body 28 has a plurality of contraction-side oil passages 28a and a plurality of extension-side oil passages 28b. In addition, 2
8c is a seal member for sealing between the cylinder 21 and the piston main body 28. The check valve 31 allows the hydraulic oil to flow through the contraction-side oil passage 28a during the contraction stroke, and prevents the flow of the hydraulic oil through the contraction-side oil passage 28a during the extension stroke.

The extension side valve 33 includes an oil passage 31a opened to the check valve 31 and an extension side oil passage 28 during the extension stroke.
It is pushed open by the hydraulic oil passing through b to generate a damping force. Reference numeral 33a denotes a cutout provided in the extension valve 33 for allowing the hydraulic oil to flow into the compression oil passage 28a.

FIG. 4 is a side view showing the operation of the vehicle brake device according to the present invention when the pedal is depressed, and shows a state in which the brake pedal is being depressed in order to decelerate the vehicle. When the brake pedal 5 is depressed, the brake damper 6 is contracted, and the operating rod 12 of the brake booster 7 is stroked to generate hydraulic pressure in the master cylinder 8 and transmitted to the wheel side to generate a braking force.

FIG. 5 is a sectional view showing the operation of the brake damper when the pedal is depressed according to the present invention, wherein the piston 22 is connected via a piston rod 24 connected to the brake pedal 5.
Moves to the contraction side, the hydraulic oil in the inner oil chamber B passes through the notch 33a and the contraction-side oil passage 28a, pushes the check valve 31 open, and flows into the outer oil chamber A.

At this time, since the check valve 31 is pressed against the piston main body 28 by the coil spring 32 having a very small elastic force, the force with which the operating oil pushes the check valve 31 open is very small. Since the cross-sectional area of the contraction-side oil passage 28a is large and has a plurality,
In this contraction stroke, little damping force is generated. In this contraction stroke, since the piston rod 24 enters the outer oil chamber A, the free piston 23 generates gas by an amount corresponding to the volume increase of the piston rod 24 in the oil chamber including the outer oil chamber A and the inner oil chamber B. Move to the room C side.

FIG. 6 is a side view showing the operation of the vehicle brake device according to the present invention immediately after the brake is released, and shows a state in which the deceleration of the vehicle is released. When the player releases his / her foot at the position indicated by the two-dot chain line, which is the stepping position of the brake pedal 5 necessary for deceleration of the vehicle, the brake pedal 5 attempts to return to the original position due to the pulling force of the return spring 9 and the hydraulic pressure of the master cylinder 8. At the same time, the brake damper 6 extends, and the operating rod 1 of the brake booster 7
2 is pulled, the hydraulic pressure generated in the master cylinder 8 gradually decreases, and the braking force on the wheel side is released.

FIG. 7 is a sectional view showing the operation of the brake damper according to the present invention immediately after the brake is released. When the piston 22 moves to the extension side via the piston rod 24 connected to the brake pedal 5, the outside oil is removed. The hydraulic oil in the chamber A passes through the oil passage 31a and the extension-side oil passage 28b, pushes and opens the extension-side valve 33, and flows into the inner oil chamber B. At this time, since a large damping force is generated by the extension side valve 33, the brake damper 6 is extended slowly, and the brake pedal 5 is also slowly returned to the original position along with this.
The braking force of the wheels is gradually released.

FIG. 8 is a diagram for explaining changes in the behavior of the vehicle before and after braking according to the present invention. The acceleration acting on the vehicle and the posture of the vehicle from before braking to after braking are represented by the braking force, the front wheel contact load and the occupant. It is shown together with the inertial force acting on. The horizontal axis represents time. The state of the vehicle will be described below.
Is described in the vehicle model. The vehicle 1 is traveling at a constant speed.

Here, braking is started. The braking force is generated by the brake device, and the vehicle 1 is decelerated. Along with this, a rearward acceleration is generated in the vehicle 1, an inertial force is generated in the vehicle 1 in a direction opposite to the direction of the acceleration (forward), the vehicle 1 leans forward, and the ground contact load of the front wheels increases. . At this time,
The inertia force also acts on the occupant in the same direction (forward) as the vehicle 1.

When the vehicle speed has decreased to a desired speed, the driver releases his / her foot from the brake pedal 5 (see FIG. 6). At this time, since the braking is gradually released by the brake damper 6 (see FIG. 6), the forward acceleration acting on the vehicle 1 is small, and the inertial force generated in the vehicle 1 in the opposite direction (rearward) to the direction of the acceleration is also reduced. small. Thereby, the suspension of the contracted front wheel is gently extended, the phenomenon of the vehicle 1 rising upward is suppressed, and the contact load of the front wheel does not suddenly decrease. Also, the inertia force generated in the occupant in the same direction (backward) as the vehicle 1 is small. The vehicle 1 returns to a substantially horizontal posture.

As described above, in FIG. 1, the brake pedal 5 constituting the vehicle brake device 3 is provided with the brake damper 6 for slowing the release of the brake. This makes it possible to suppress a sudden change in the acceleration of the vehicle rearward during braking to the vehicle frontward, thereby suppressing discomfort of the occupant.

Also, immediately after FIG. 8, since the front wheel contact load remains, for example, when the brake is released immediately before cornering, the frictional force between the front wheels and the road surface at the beginning of cornering, that is, the cornering force decreases. Without slipping, the outside slip of the front wheels is suppressed,
There is no loss of running stability.

FIG. 9 is a sectional view showing another embodiment of the automotive brake system according to the present invention, and shows that a brake damper is provided at the rear of the brake booster. The vehicle brake device 40 has a brake damper 41 attached to an end of the brake booster 7 via an attachment member 71. Reference numeral 72 denotes the brake booster 7 and the brake damper 4
1 is a bolt for attaching 1 to a vehicle body.

The brake damper 41 includes a cylinder 42,
A piston 43 slidably inserted into the cylinder 42
And an operating rod 44 attached to the piston 43, and a first rod guide 45 and a second rod guide 46 supporting the operating rod 44.

The brake damper 41 is mounted on the cylinder 4
2 is partitioned by a piston 43 into an outer oil chamber D and an inner oil chamber E.
And 47 and 48 are the first rod guides 4
O-rings 51 and 52 are mounted on the inner and outer circumferences of the second rod guide 46, respectively.

The piston 43 includes a piston body 54, a check valve 55 provided on the outer oil chamber D side of the piston body 54, and the check valve 55
A coil spring 56 for pressing the piston body 4 and an extension valve 5 provided on the inner oil chamber E side of the piston body 54
7 Reference numerals 61 and 62 denote washers and nuts for fixing the piston 43 to the operating rod 44.

The operating rod 44 has a pedal mounting portion 44a for mounting on a brake pedal, a first straight portion 44b, and a second straight portion 44c.
The first straight portion 44b slides on the O-ring 47, and the second straight portion 44c slides on the O-ring 51. The first straight portion 44b and the second straight portion 44
The outer diameter of c is equal, and the volume of the oil chamber including the outer oil chamber D and the inner oil chamber E does not change with the stroke of the operating rod 44.

The piston body 54 has a plurality of contraction-side oil passages 54a and a plurality of extension-side oil passages 54b. The check valve 55 allows the hydraulic oil to flow through the compression-side oil passage 54a during the contraction stroke, and prevents the hydraulic oil from flowing through the compression-side oil passage 54a during the extension stroke.

The extension side valve 57 includes an oil path 55a opened to the check valve 55 and an extension side oil path 54 during the extension stroke.
It is pushed open by the hydraulic oil passing through b to generate a damping force. Reference numeral 57a denotes a cutout provided in the extension side valve 57 for allowing hydraulic oil to flow into the contraction side oil passage 54a, and 63 denotes a seal member attached to the piston body 54.

The operation of the brake damper 41 is the same as the operation of the brake damper 6, and a description thereof will be omitted.

As described above, in FIG. 9, the brake booster 7 constituting the vehicle brake device 40 is provided with the brake damper 41 for slowing the release of the brake. , The sudden change of the vehicle rearward acceleration during braking to the vehicle frontward direction can be suppressed, and the discomfort of the occupant can be suppressed.

The brake damper 6 (see FIG. 1) of the present invention is configured to generate a damping force during the extension stroke and hardly generate a damping force during the contraction stroke. The positional relationship with the brake pedal 5 (see FIG. 1) is changed.
By mounting the brake damper 6 (see FIG. 1) before (see FIG. 1), the damping force may be generated during the contraction stroke, and the damping force may be hardly generated during the extension stroke.

The brake damper 6 may be a rotary damper.

[0035]

According to the present invention, the following effects are exhibited by the above configuration. In the vehicle brake damper of the first aspect, the brake pedal or the brake booster constituting the vehicle brake device is provided with a damping force generating mechanism for slowing the release of the brake. The release is gradually performed, so that the vehicle rearward acceleration at the time of braking can be prevented from suddenly changing in the vehicle forward direction, and the occupant's discomfort can be suppressed.

[Brief description of the drawings]

FIG. 1 is a side view showing a pedal portion of an automobile brake device according to the present invention.

FIG. 2 is a graph showing characteristics of a brake damper according to the present invention.

FIG. 3 is a sectional view of a brake damper according to the present invention.

FIG. 4 is a side view showing the operation of the vehicle brake device according to the present invention when the pedal is depressed.

FIG. 5 is a sectional view showing the operation of the brake damper when the pedal is depressed according to the present invention.

FIG. 6 is a side view showing an operation immediately after the brake is released in the automobile brake device according to the present invention.

FIG. 7 is a sectional view showing the operation of the brake damper immediately after releasing the brake according to the present invention.

FIG. 8 is a diagram illustrating a behavior change before and after braking of the vehicle according to the present invention.

FIG. 9 is a cross-sectional view showing another embodiment of the automotive brake device according to the present invention.

FIG. 10 is a diagram illustrating a change in behavior of a conventional vehicle before and after braking.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Automobile (vehicle), 2 ... Car body, 3,40 ... Automotive brake device, 5 ... Brake pedal, 6,41 ... Damping force generation mechanism (brake damper), 7 ... Brake booster.

Claims (1)

[Claims] 1. A vehicle brake device comprising a brake pedal or a brake booster constituting the vehicle brake device, wherein a damping force generating mechanism for slowing the release of the brake is provided.