CN108253045B - Clearance self-modulation type drum brake - Google Patents
Clearance self-modulation type drum brake Download PDFInfo
- Publication number
- CN108253045B CN108253045B CN201810043456.4A CN201810043456A CN108253045B CN 108253045 B CN108253045 B CN 108253045B CN 201810043456 A CN201810043456 A CN 201810043456A CN 108253045 B CN108253045 B CN 108253045B
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- CN
- China
- Prior art keywords
- brake
- brake shoe
- eccentric bushing
- pawl
- ratchet wheel
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/02—Braking members; Mounting thereof
- F16D65/10—Drums for externally- or internally-engaging brakes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/38—Slack adjusters
- F16D65/40—Slack adjusters mechanical
- F16D65/52—Slack adjusters mechanical self-acting in one direction for adjusting excessive play
- F16D65/58—Slack adjusters mechanical self-acting in one direction for adjusting excessive play with eccentric or helical body
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Braking Arrangements (AREA)
Abstract
The invention relates to a clearance self-adjusting drum brake, which comprises a brake shoe, a supporting pin, an eccentric bushing, a ratchet-pawl mechanism and the like. The fixed end of the brake shoe is arranged on the brake bottom plate through the bearing pin and the eccentric bushing, and an actuating element of the brake system drives the brake shoe to be expanded and tightly pressed on the brake drum, so that a high-efficiency brake effect is realized. When the brake shoe rotates reversely and returns, the brake clearance at the fixed end is automatically adjusted through the rotation of the ratchet wheel and pawl mechanism and the eccentric bushing. The invention has simple structure, reliable work and high braking efficiency, and can automatically adjust the braking clearance at the fixed end of the brake shoe and compensate the influence caused by the abrasion of the friction plate.
Description
Technical Field
The invention relates to the field of brakes, in particular to a drum brake, which can realize the automatic adjustment of the brake clearance of the brake at the fixed end of a brake shoe, and particularly relates to a clearance self-adjusting drum brake.
Background
The brake system of the automobile comprises an energy supply device, a control device, a transmission device and a brake, and the brake used on the automobile at present mainly comprises a disc brake and a drum brake. The brakes gradually reduce the speed of the automobile in a friction mode to realize speed reduction or parking, and in the using process of the brakes, the friction causes abrasion of friction plates, the braking clearance of the brakes is gradually increased, the change of the braking clearance and unbalance of the braking clearances of wheels can cause the reduction of the braking performance of the automobile, and certain potential safety hazards are brought. Therefore, adjusting the brake clearance of the brake to keep the brake clearance within a normal range is an important content in the maintenance process of the automobile brake system.
Drum brakes are widely used in automobiles, and the actuation modes include hydraulic piston actuation, cam actuation and the like. The brake clearance adjustment of the drum brake comprises the brake clearance adjustment of a brake shoe actuating end and the brake clearance adjustment of a brake shoe fixing end. The fixed end of the drum brake shoe is often positioned by a support pin or a boss, and the clearance adjusting mode is often manually adjusted, so that the timeliness and the accuracy are difficult to ensure when the braking clearance is adjusted manually, particularly the consistency among the brakes, the labor cost is increased, and the service time of a vehicle is shortened.
The invention can realize the automatic adjustment of the brake clearance at the fixed end of the brake shoe of the drum brake, reduce the labor cost, increase the transportation and use time of the vehicle and ensure the consistent brake clearance among the brakes of all wheels.
The invention is different from the invention patent CN200710017418.3 in that: the invention realizes the automatic adjustment of the braking clearance at the fixed end of the brake shoe by installing the eccentric bushing and the ratchet pawl mechanism at the fixed end of the brake shoe. The pawl is arranged on the braking bottom plate, the central position of the ratchet wheel is always kept unchanged, and the matching state of the pawl and the ratchet wheel is kept unchanged. In the invention patent CN200710017418.3, the brake clearance adjustment of the fixed end of the brake shoe is realized by adopting a ratchet wheel, a positioning pawl, a supporting shoe pin shaft, a ratchet wheel integrated double-working-face cam, a cam shaft and the like, the positioning pawl pin shaft is arranged on the extension part of the brake shoe, and in the clearance adjustment work, the integrally-working ratchet wheel leaves the working axis and generates position change and radial change with the positioning pawl and the positioning pawl at a certain distance, so that the curve type ratchet wheel is formed by compounding the Archimedes curve transition circle center with the line shape reduced.
Disclosure of Invention
Aiming at the problem of adjusting the braking clearance of the drum brake actuated by the cam of the modern automobile, the invention aims to provide a clearance self-adjusting type drum brake, which realizes the automatic adjustment of the braking clearance at the fixed end of the brake shoe of the drum brake. The invention has the advantages of simple structure, reliable work and the like, can realize the automatic adjustment of the brake clearance at the fixed end of the brake shoe, and ensures the brake balance and the brake efficiency stability of the automobile.
The technical scheme for realizing the purpose of the invention is as follows:
a clearance self-adjusting drum brake comprises a brake shoe, a bearing pin, an eccentric bushing, a ratchet wheel, a pawl and a pawl spring; the method is characterized in that: the supporting pin is fixedly arranged on the brake bottom plate, the eccentric bushing is arranged on the supporting pin, the brake shoe fixing end shaft hole is matched with the eccentric bushing and supported on the brake bottom plate, the ratchet wheel coaxial with the supporting pin is fixedly arranged or processed on the eccentric bushing, and the pawl is arranged on the brake bottom plate and meshed with the ratchet wheel under the action of the pawl spring;
during braking, an actuating element of a braking system opens the brake shoe, the brake shoe and the eccentric bushing rotate together around the bearing pin, the ratchet wheel also rotates together, the tooth end of the pawl slides on the gear teeth of the ratchet wheel, when the friction plate on the brake shoe is not worn greatly or is not worn, the sliding range of the tooth end of the pawl on the gear teeth of the ratchet wheel is not more than one gear tooth, braking is released, when the brake shoe is reset, the pawl is still pressed against the same gear tooth of the ratchet wheel, and no relative displacement exists between the brake shoe and the eccentric bushing; when the friction plate on the brake shoe is worn out to exceed a certain range, the sliding range of the tooth end of the pawl on the gear tooth of the ratchet wheel exceeds one tooth, the brake is released, and when the brake shoe is reversely returned, the pawl enables the ratchet wheel to be positioned at a new working position, namely the eccentric bushing is positioned at a new position, so that the brake shoe fixed end rotates a certain angle relative to the eccentric bushing, the brake shoe fixed end is enabled to be closer to the brake drum, and the automatic adjustment of the brake clearance of the brake shoe fixed end is realized.
The friction force between the brake shoe fixing end shaft hole and the eccentric bushing is larger than the friction force between the eccentric bushing and the supporting pin.
The friction torque between the brake shoe fixed end shaft hole and the eccentric bushing is smaller than the return torque of the brake shoe.
When the ratchet wheel rotates for a larger angle and the tooth end of the pawl slides from one tooth of the ratchet wheel to another tooth, the ratchet wheel cannot rotate reversely under the action of the pawl spring so that the tooth end of the pawl returns to the previous tooth again.
The center of the eccentric bush matched with the shaft hole of the fixed end of the brake shoe is always closer to the symmetric center line of the brake and the actuating end of the brake shoe than the center of the supporting pin.
Drawings
Fig. 1 is a front view of an embodiment of a self-adjusting clearance drum brake of the present invention.
Fig. 2 is a sectional view of an eccentric bush of an embodiment of a self-clearance adjusting type drum brake of the present invention.
The description is marked in the drawings: 1-brake drum 2-friction plate 3-brake shoe 4-bearing pin 5-pawl spring 6-ratchet 7-pawl 8-eccentric bush
Detailed Description
An embodiment of the present invention will be described in detail with reference to fig. 1 and 2.
As shown in figure 1, the drum brake with self-adjusting clearance comprises a supporting pin 4 fixedly arranged on a brake bottom plate, an eccentric bushing 8 sleeved on the supporting pin 4, a ratchet wheel 6 machined on the eccentric bushing 8, a pawl 7 arranged on the brake bottom plate and meshed with the ratchet wheel 6 under the action of a pawl spring 5, a fixed end shaft hole of a brake shoe 3 is matched with the eccentric bushing 8, and a friction plate 2 is arranged on the brake shoe 3.
During braking operation, the brake shoe 3 is spread by the actuating element of the braking system, the friction between the eccentric bushing 8 and the brake shoe 3 is greater than the friction between the eccentric bushing 8 and the anchor pin 4, so that the brake shoe 3 and the eccentric bushing 8 rotate together about the center of the anchor pin 4, the ratchet 6 is rotated, and the tooth ends of the pawl 7 slide on the teeth of the ratchet 6. If the friction plate 2 has no wear or has little wear, the sliding range of the pawl 7 on the ratchet wheel 6 does not exceed one pitch, and sufficient braking torque can be obtained. When the brake is released, all the elements return under the action of the brake return device. If the abrasion of the friction plate 2 exceeds a certain range, the pawl 7 slides from one tooth of the ratchet wheel 6 to the next tooth, when the brake is released, the eccentric bushing 8 is positioned at a new working position, the brake shoe 3 is returned under the action of the return device, rotates relative to the eccentric bushing 8 by a certain angle and stays at the new working position closer to the brake drum 1, and the automatic adjustment of the brake clearance at the fixed end of the brake shoe 3 is realized.
Claims (5)
1. A clearance self-adjusting drum brake comprises a brake shoe, a bearing pin, an eccentric bushing, a ratchet wheel, a pawl and a pawl spring; the method is characterized in that: the supporting pin is fixedly arranged on the brake bottom plate, the eccentric bushing is arranged on the supporting pin, the brake shoe fixing end shaft hole is matched with the eccentric bushing and supported on the brake bottom plate, the ratchet wheel coaxial with the supporting pin is fixedly arranged or processed on the eccentric bushing, and the pawl is arranged on the brake bottom plate and meshed with the ratchet wheel under the action of the pawl spring;
during braking, an actuating element of a braking system opens the brake shoe, the brake shoe and the eccentric bushing rotate together around the bearing pin, the ratchet wheel also rotates together, the tooth end of the pawl slides on the gear teeth of the ratchet wheel, when the friction plate on the brake shoe is not worn greatly or is not worn, the sliding range of the tooth end of the pawl on the gear teeth of the ratchet wheel is not more than one gear tooth, braking is released, when the brake shoe is reset, the pawl is still pressed against the same gear tooth of the ratchet wheel, and no relative displacement exists between the brake shoe and the eccentric bushing; when the friction plate on the brake shoe is worn out to exceed a certain range, the sliding range of the tooth end of the pawl on the gear tooth of the ratchet wheel exceeds one tooth, the brake is released, and when the brake shoe is reversely returned, the pawl enables the ratchet wheel to be positioned at a new working position, namely the eccentric bushing is positioned at a new position, so that the brake shoe fixed end rotates a certain angle relative to the eccentric bushing, the brake shoe fixed end is enabled to be closer to the brake drum, and the automatic adjustment of the brake clearance of the brake shoe fixed end is realized.
2. A gap self-adjusting drum brake as defined in claim 1, wherein a frictional force between said brake shoe retaining end shaft hole and said eccentric bushing is greater than a frictional force between said eccentric bushing and said anchor pin.
3. A gap self-adjusting drum brake as defined in claim 1, wherein a friction torque between said brake shoe retaining end shaft opening and said eccentric bushing is less than a return torque of said brake shoe.
4. A gap self-adjusting drum brake as defined in claim 1, wherein when said ratchet wheel rotates at a large angle and said pawl tooth end slides from one tooth to another tooth of said ratchet wheel, said ratchet wheel cannot be reversed under the action of said pawl spring to return said pawl tooth end to the previous tooth.
5. A gap self-adjusting drum brake as defined in claim 1, wherein the center of said eccentric bushing engaged with said brake shoe retaining end shaft hole is always closer to the brake center line of symmetry and said brake shoe actuating end than the center of said anchor pin.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810043456.4A CN108253045B (en) | 2018-01-12 | 2018-01-12 | Clearance self-modulation type drum brake |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810043456.4A CN108253045B (en) | 2018-01-12 | 2018-01-12 | Clearance self-modulation type drum brake |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108253045A CN108253045A (en) | 2018-07-06 |
| CN108253045B true CN108253045B (en) | 2020-03-10 |
Family
ID=62726704
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810043456.4A Active CN108253045B (en) | 2018-01-12 | 2018-01-12 | Clearance self-modulation type drum brake |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108253045B (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5435419A (en) * | 1993-08-11 | 1995-07-25 | Muzzy; Robert G. | Drum brake wear adjustor with eccentric roller and pawl assembly |
| CN203051555U (en) * | 2012-12-06 | 2013-07-10 | 重庆市双桥区中帝汽车配件制造有限公司 | Drum brake assembly of medium trucks and heavy trucks |
| CN103470661A (en) * | 2013-09-22 | 2013-12-25 | 太仓康茂电子有限公司 | Clearance self-adjusting device |
| CN107477109B (en) * | 2017-08-28 | 2019-03-22 | 浙江师范大学 | A kind of electric mechanical brake-by-wire device |
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2018
- 2018-01-12 CN CN201810043456.4A patent/CN108253045B/en active Active
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| Publication number | Publication date |
|---|---|
| CN108253045A (en) | 2018-07-06 |
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