JP4302226B2 - Drum brake device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention has a very high braking effect and can obtain a very large braking force even with a small input. Therefore, the present invention is suitable for downsizing of a brake device, and further suitable for downsizing and electrification of a brake input actuator. The present invention relates to a drum brake device having a new configuration.
[0002]
[Prior art]
In recent vehicle brake devices, intelligent brake functions such as anti-lock brake systems and traction control systems are being actively used. And in order to cope with such intelligentization, the braking device is being electrified.
Furthermore, recently, from the viewpoint of preventing environmental destruction caused by exhaust gas, attention has been focused on the development of hybrid cars that use an electric motor and a gasoline engine in combination as driving sources, or electric vehicles that limit the driving source to only electric motors. As a brake device mounted on these hybrid cars and electric cars, downsizing and electrification have become important issues that cannot be separated.
[0003]
Recently, a duo-servo drum brake device has attracted attention as a brake device suitable for miniaturization.
2. Description of the Related Art A duo-servo type drum brake device generally includes a primary shoe and a secondary shoe, which are a pair of brake shoes disposed opposite to each other in a cylindrical drum. In the primary shoe, the forward rotation direction inlet side of the drum is used as an input portion, and the forward rotation direction outlet side of the drum is connected to the inlet side of the secondary shoe via an adjuster, for example. On the other hand, the outlet side of the secondary shoe is brought into contact with an anchor portion provided on the backing plate, and the anchor reaction force acting on the primary shoe and the secondary shoe is received by the anchor portion.
[0004]
As a result, when the primary shoe and the secondary shoe are expanded and pressed against the inner peripheral surface of the drum, the anchor reaction force acting on the primary shoe is input to the inlet side of the secondary shoe so as to press the secondary shoe against the inner peripheral surface of the drum. Therefore, both the primary shoe and the secondary shoe operate as the leading shoe, and a very high gain braking force can be obtained. Compared to the leading trailing and two leading drum brake devices, An extremely high braking force can be obtained, and the size can be reduced.
[0005]
[Problems to be solved by the invention]
However, when considered as a brake device mounted on the hybrid car or electric vehicle described above, it is difficult to say that the conventional duo-servo type drum brake device is sufficiently effective.
The conventional duo-servo type drum brake device has a high braking effect and can easily obtain a large braking force when compared with other drum brake devices such as a leading trailing type and a two-leading type or a disc brake device. Although it has an advantage, in order to ensure the braking force required for the running performance of the vehicle, a certain large force is required as a brake input.
Therefore, it is necessary to incorporate a booster mechanism into a hydraulic pressure supply mechanism that supplies hydraulic pressure to a brake input actuator (for example, a wheel cylinder) that opens a brake shoe, a lever mechanism that operates a parking brake, etc. It cannot be simplified as a drive source for brake input alone, and a booster mechanism must be incorporated on the brake input side, so miniaturization is sacrificed or motorization becomes difficult There was a problem of becoming.
[0006]
The present invention has been made in view of the above circumstances, and has an extremely high braking effect, and can obtain a very large braking force even with a small input. Therefore, the present invention is suitable for downsizing of a brake device. An object of the present invention is to provide a drum brake device having a new configuration suitable for miniaturization and electrification.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a drum brake device according to the present invention includes a single brake input actuator that widens a brake shoe, and a position that makes one or more rounds of the inner circumference of the drum from the input position of the brake input actuator. A brake shoe row including an anchor pin disposed and a brake shoe row in which an input end of a brake shoe at a start end is in contact with an output member of the brake input actuator and an output end of a brake shoe at a terminal end is in contact with the anchor pin. The row is characterized in that at least three or more brake shoes are connected so as to go around the inner circumference of the drum two or more times in order along the circumferential direction of the drum via a link capable of transmitting torque .
[0008]
According to the above configuration, during braking, when the brake shoes constituting the brake shoe row are pressed against the inner periphery of the drum by the output of the brake input actuator, the brake shoes adjacent to each other in the circumferential direction of the drum Are connected via a link capable of transmitting torque, and at each link coupling portion, the anchor reaction force of the brake shoe positioned on the drum rotation direction inlet side of the brake shoe positioned on the drum rotation direction outlet side is Servo action that acts as input and enhances braking effectiveness. And, the fact improve brake effectiveness by the servo action in the link coupling portions, for synergy over two laps of the drum, brake effectiveness is very high, to obtain a braking force which is a very large output even with a small input Can do.
In the drum brake device according to the present invention, in the drum brake device having the above-described configuration, a strain that detects a strain amount of the anchor pin from an anchor reaction force that acts on the anchor pin when the brake shoe at the terminal end abuts. A detection means and a control means for controlling the output of the brake input actuator by monitoring the output of the distortion detection means may be provided.
According to the above configuration, it is possible to prevent the braking performance of the braking torque from being deteriorated due to a disturbance, and it is possible to stabilize the effectiveness while ensuring high braking effectiveness.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a drum brake device according to the invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view of an assembled state of an embodiment of a drum brake device according to the present invention, FIG. 2 is an exploded perspective view of the drum brake device shown in FIG. 1, and FIG. 3 is another example of the drum brake device shown in FIG. 4 is a front view of the assembled state of the drum brake device, FIG. 5 is a plan view of the assembled state of the drum brake device, and FIG. 6 is a brake shoe row of the drum brake device shown in FIG. FIG. 7 is a plan view showing the relationship between the second brake shoe and the third brake shoe, and FIG. 7 is a diagram showing the first brake shoe and the fourth brake shoe in the brake shoe row of the drum brake device shown in FIG. It is a top view which shows the relationship.
[0010]
This drum brake device 1 has a single brake input actuator 3 for expanding the brake shoe and pressing it to the inner periphery of a drum (not shown), and the inner periphery of the drum 1 from the input position where the brake input actuator 3 acts. The structure is provided with an anchor pin 5 disposed at a position that has been rotated around the circumference and a brake shoe row 7 that is expanded by the brake input actuator 3.
[0011]
The brake input actuator 3 is a so-called double-acting hydraulic wheel cylinder cylinder. As shown in FIG. 4, the brake input actuator 3 is provided at both ends of a cylinder body 3a fixed to a backing plate 9 for driving a brake shoe as an output member. Pistons 3b and 3c are equipped. These pistons 3b and 3c are advanced from the cylinder body 3a by the hydraulic pressure supplied from the master cylinder into the cylinder body 3a according to the brake operation, and the brake shoes that are in contact with the piston 3b and 3c are opened to expand the drum inner circumference (not shown). Press against the surface. The backing plate 9 is fixed to the vehicle body side.
[0012]
The brake shoe row 7 includes four brake shoes, a first brake shoe 11, a second brake shoe 12, a third brake shoe 13, and a fourth brake shoe 14, and these brake shoes connected in order. A brake shoe array is provided that includes link mechanisms 16, 17, and 18 that enable torque transmission between the brake shoes adjacent to each other in the circumferential direction of the drum. ing.
[0013]
In the brake shoe row 7, the first brake shoe 11 is a brake shoe at the start end in a brake shoe array in which four brake shoes are connected. In the first brake shoe 11, the base end corresponding to the inlet side in the forward rotation direction of the drum is connected to the piston 3 b that is an output member of the brake input actuator 3 so that the brake input actuator 3 is expanded during braking. The contact is made via the rod member 28. The first brake shoe 11 is urged against the brake input actuator 3 by a spring member 21 spanned between a pin 11 a protruding from the brake shoe 11 and a pin 3 d protruding from the brake input actuator 3. Yes.
[0014]
The second brake shoe 12 is a brake shoe disposed opposite to the first brake shoe 11, and the base end corresponding to the inlet side in the drum forward rotation direction has the link mechanism 16 at the output end of the first brake shoe 11. Are connected through.
In the case of the present embodiment, the link mechanism 16 is an adjuster that adjusts the position of the brake shoes 11 and 12 in accordance with the amount of wear on the friction surface in order to keep the gap between the friction surface of the brake shoe and the drum at an appropriate value. Yes, during braking, the braking torque acting on the first brake shoe 11 is transmitted to the second brake shoe 12 by the link mechanism 16.
[0015]
The first brake shoe 11 and the second brake shoe 12 are in a state where the output end of the first brake shoe 11 and the input end of the second brake shoe 12 are in contact with the link mechanism 16 that is an adjuster. It is urged | biased by the direction which approaches mutually by the spring member 23 so that it may be maintained.
Further, the second brake shoe 12 is widened by the brake input actuator 3 at the time of braking, and the tip side corresponding to the outlet side in the drum forward rotation direction is connected to the piston 3c which is an output member of the brake input actuator 3. The contact is made through the rod member 29 and the interlocking rod 24.
[0016]
The third brake shoe 13 has a structure in which a pair of brake shoes 13 a and 13 b sandwiching the first brake shoe 11 is integrated, and the base end corresponding to the inlet side in the drum forward rotation direction is the first by the link mechanism 17. The brake shoe 12 is connected to the tip of the second brake shoe 12.
In the case of the present embodiment, the link mechanism 17 is a connecting pin that rotatably connects the distal end portion of the second brake shoe 12 and the proximal end portion of the third brake shoe 13. As shown in FIG. 3, the third brake shoe 13 has a structure having a shoe insertion opening 13a through which the first brake shoe 11 is inserted, and the first brake shoe 11 has a shoe insertion opening. The part 13a is assembled in a nested state. At the time of braking, when the first brake shoe 11 is expanded by the piston 3b of the brake input actuator 3, the third brake shoe 13 is expanded in conjunction with the first brake shoe 11 and the drum. Pressed.
Further, as shown in FIG. 6, the third brake shoe 13 is transmitted by the link mechanism 17 with a braking torque acting on the second brake shoe 12.
[0017]
The fourth brake shoe 14 is a terminal brake shoe in a brake shoe arrangement in which four brake shoes are connected, and is disposed opposite to the third brake shoe 13. As shown in FIG. 4, the fourth brake shoe 14 has a base end corresponding to the inlet side in the drum forward rotation direction connected to the output end of the third brake shoe 13 via a link mechanism 18. Yes. The link mechanism 18 is an adjuster that adjusts the position of the brake shoes 13 and 14 in accordance with the amount of wear of the friction surfaces in order to keep the gap between the friction surfaces of the brake shoes 13 and 14 and the drum at an appropriate value. Sometimes, the braking torque acting on the third brake shoe 13 is transmitted to the fourth brake shoe 14 by the link mechanism 18.
The third brake shoe 13 and the fourth brake shoe 14 are in a state where the output end of the third brake shoe 13 and the input end of the fourth brake shoe 14 are in contact with the link mechanism 18 that is an adjuster. It is urged | biased by the spring member 22 in the direction which approaches mutually so that it may be maintained.
[0018]
As shown in FIG. 3, the fourth brake shoe 14 described above has a structure having a shoe insertion opening 14 a through which the second brake shoe 12 is inserted, and the second brake shoe 12 is a shoe insertion opening. 14a is assembled in a nested state. During braking, when the second brake shoe 12 is expanded by the piston 3 c of the brake input actuator 3, the fourth brake shoe 14 is interlocked with the second brake shoe 12 by the interlocking rod 24. Expanded and pressed against the drum.
Further, in the fourth brake shoe 14, braking torque acting on the third brake shoe 13 is further transmitted by the link mechanism 18.
[0019]
Further, the output end of the fourth brake shoe 14 is brought into contact with the anchor pin 5 and is kept in contact with the anchor pin 5 by a spring member 25 (see FIG. 4). It is biased to the 5th side. As a result, the anchor reaction force acting on the fourth brake shoe 14 which is the terminal brake shoe is transmitted to the anchor pin 5 and becomes the braking torque generated by the drum brake device 1.
[0020]
The brake shoe row 7 having the above configuration includes a shoe hold-down device in which the first brake shoe 11 and the third brake shoe 13 and the second brake shoe 12 and the fourth brake shoe 14 are fixed to the backing plate 9, respectively. 26 and 27 are supported so as to be expandable.
[0021]
Although not shown in the present embodiment, the magnitude of the braking torque is determined in real time from the amount of distortion of the anchor pin 5 due to the anchor reaction force attached to the anchor pin 5 and acting from the fourth brake shoe 14. A strain gauge serving as a strain detection means to detect, and a feedback control section serving as a control means for controlling the output of the brake input actuator 3 so as to monitor the output of the strain gauge and keep the output of the strain gauge within a specified range; Equipped with.
[0022]
That is, in the drum brake device 1 described above, at the time of braking, the first to fourth brake shoes 11, 12, 13, 14 constituting the brake shoe row 7 are formed by the advancement of the pistons 3 b, 3 c of the brake input actuator 3. The sum of the sliding frictional forces that are spread and pressed against the drum and act on each of the brake shoes 11, 12, 13, and 14 becomes the braking force generated by the brake device.
[0023]
In the brake shoe row 7 described above, the brake shoes adjacent to each other in the circumferential direction of the drum are connected to each other via link mechanisms 16, 17, and 18 capable of transmitting torque. The anchor reaction force of the brake shoe located on the rotational direction inlet side acts as an input of the brake shoe located on the rotational direction outlet side of the drum, and a servo action is performed to increase the braking effectiveness. And since the improvement of the brake effect by the servo action in each link coupling part synergizes over the two revolutions of the drum, the brake effect is extremely high, and a very large braking force can be obtained even with a small input.
[0024]
Therefore, it is suitable for downsizing of the brake device, and further suitable for downsizing and electrification of the brake input actuator. For example, the drum brake device can be housed on the inner peripheral side of the in-wheel motor of a hybrid car or electric vehicle. It is possible to simplify the use of a low-power small motor as a single unit for the brake input actuator 3 which is a drive source for brake input, so that a small brake mounted on a hybrid car or an electric vehicle can be achieved. It is also useful as a device.
[0025]
In addition, since the brake input is small, fail safe in the event of electric failure of the electric brake can be completely supplemented with pedal depression force and lever pulling force, making it easier to improve safety and reliability. .
Further, in the present embodiment, the actual braking torque is detected in real time by the output of the strain gauge mounted on the anchor pin 5, and the feedback control unit controls the brake input actuator 3 so that the output of the strain gauge falls within the specified range. Therefore, the deterioration of the controllability of the braking torque due to disturbance can be prevented, and the effectiveness can be stabilized while ensuring high braking effectiveness.
[0026]
In the present embodiment, the brake shoe row 7 is composed of first to fourth four brake shoes 11, 12, 13, and 14, and each brake is rotated so that the inner periphery of the drum is rotated twice. Although the shoe dimensions and the like are set, the number of revolutions of the inner periphery of the drum by the brake shoe row and the number of brake shoes to be configured are not limited to the above embodiment.
For example, the brake shoe train has a structure in which at least three brake shoes are linked and connected along the inner circumference of the drum, and the number of revolutions in the drum is one or more. Can obtain a large servo effect and generate a large braking force.
Further, in order to obtain a desired braking force, a material that changes the friction coefficient between the first and second brake shoes 11 and 12 and the third and fourth brake shoes 13 and 14 is selected, or the sliding surface It can also be formed by changing the width.
[0027]
In the above embodiment, the first brake shoe 11 and the second brake shoe 12 are arranged opposite to each other in the brake shoe row, and the third brake shoe 13 and the fourth brake shoe 14 are further arranged. The brake shoes are connected in order so as to be opposed to each other. For example, it is conceivable to connect the brake shoes in order so that the brake shoe row draws a spiral on the inner periphery of the drum.
[0028]
In the drum brake device of the present invention, the single brake input actuator used for expanding the brake shoe is not limited to the above embodiment. For example, as described above, there are various types such as a structure in which the piston member that contacts the brake shoe is linearly driven back and forth by a small electric power small motor, or a structure that uses a telescopic operation such as a giant magnetostrictive element. Things are available.
[0029]
【The invention's effect】
According to the drum brake device of the present invention, at the time of braking, when the brake shoes constituting the brake shoe row are pressed against the inner periphery of the drum by the output of the brake input actuator, the brake shoes adjacent in the circumferential direction of the drum Since the links are connected to each other through links capable of transmitting torque, the brake reaction force of the brake shoe positioned on the drum rotation direction inlet side is the brake shoe positioned on the drum rotation direction outlet side in each link coupling portion. Servo action that works as an input to increase the braking effectiveness.
For example, if the brake shoe train is configured to make two rounds of the inner circumference of the drum, the improvement in brake effectiveness due to the servo action at each link coupling portion synergizes over the two revolutions of the drum. Is extremely high, and a very large braking force can be obtained even with a small input.
Therefore, it is suitable for downsizing of the brake device, and further suitable for downsizing and electrification of the brake input actuator. For example, it is possible to simplify the low power small motor as a drive source for brake input alone. Therefore, it is also useful as a small brake device mounted on a hybrid car or an electric vehicle.
[Brief description of the drawings]
FIG. 1 is a perspective view of an assembled state of an embodiment of a drum brake device according to the present invention.
FIG. 2 is an exploded perspective view of the drum brake device shown in FIG.
FIG. 3 is an exploded perspective view of the drum brake device shown in FIG. 1 as seen from another direction.
4 is a front view of the drum brake device shown in FIG. 1 in an assembled state. FIG.
5 is a plan view of an assembled state of the drum brake device shown in FIG. 1. FIG.
6 is a plan view showing a relationship between a second brake shoe and a third brake shoe in the brake shoe row of the drum brake device shown in FIG. 1. FIG.
7 is a plan view showing a relationship between a first brake shoe and a fourth brake shoe in the brake shoe row of the drum brake device shown in FIG. 1. FIG.
[Explanation of symbols]
1 Drum brake device 3 Brake input actuator (wheel cylinder)
3b, 3c Output member (piston)
5 Anchor pin 7 Brake shoe row 9 Backing plate 11 First brake shoe 12 Second brake shoe 13 Third brake shoe 14 Fourth brake shoe 16 Link mechanism (adjuster)
17 Link mechanism (connecting pin)
18 Link mechanism (adjuster)

Claims (2)

A single brake input actuator for expanding the brake shoe, an anchor pin arranged at a position that makes one or more rounds of the inner circumference of the drum from the input position of the brake input actuator, and the input end of the brake shoe at the start end is the brake input A brake shoe row that abuts against an output member of the actuator and an output end of a terminal brake shoe abuts against the anchor pin, and the brake shoe row is a link through which at least three brake shoes can transmit torque. drum brake device characterized by comprising coupled so as to surround the drum circumference 2 weeks or more in order along the circumferential direction of the drum through.   A strain detecting means for detecting a strain amount of the anchor pin from an anchor reaction force acting on the anchor pin by the contact of the brake shoe at the end, and an output of the strain detecting means to monitor the output of the brake input actuator The drum brake device according to claim 1, further comprising control means for controlling output.

Images