GB2339868A - A wheel cylinder for a drum brake - Google Patents

A wheel cylinder for a drum brake Download PDF

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Publication number
GB2339868A
GB2339868A GB9907995A GB9907995A GB2339868A GB 2339868 A GB2339868 A GB 2339868A GB 9907995 A GB9907995 A GB 9907995A GB 9907995 A GB9907995 A GB 9907995A GB 2339868 A GB2339868 A GB 2339868A
Authority
GB
United Kingdom
Prior art keywords
wheel cylinder
cylinder
piston member
piston
brake
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9907995A
Other versions
GB2339868B (en
GB9907995D0 (en
Inventor
Luigi Cucinotta
David Peasley
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Automotive Products PLC
Automotive Products USA Inc
Original Assignee
Automotive Products PLC
Automotive Products USA Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Automotive Products PLC, Automotive Products USA Inc filed Critical Automotive Products PLC
Publication of GB9907995D0 publication Critical patent/GB9907995D0/en
Publication of GB2339868A publication Critical patent/GB2339868A/en
Application granted granted Critical
Publication of GB2339868B publication Critical patent/GB2339868B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • 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
    • F16D51/00—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like
    • F16D51/16—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis
    • F16D51/18—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis with two brake-shoes
    • 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
    • F16D65/14—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position
    • F16D65/16—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position arranged in or on the brake
    • F16D65/22—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position arranged in or on the brake adapted for pressing members apart, e.g. for drum brakes
    • 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
    • F16D2121/00—Type of actuator operation force
    • F16D2121/02—Fluid pressure
    • 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
    • F16D2121/00—Type of actuator operation force
    • F16D2121/14—Mechanical
    • 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
    • F16D2123/00—Multiple operation forces
    • 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
    • F16D2125/00—Components of actuators
    • F16D2125/02—Fluid-pressure mechanisms
    • F16D2125/04—Cylinders
    • 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
    • F16D2125/00—Components of actuators
    • F16D2125/02—Fluid-pressure mechanisms
    • F16D2125/06—Pistons
    • 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
    • F16D2250/00—Manufacturing; Assembly
    • F16D2250/0023—Shaping by pressure

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Braking Arrangements (AREA)

Description

2339868 DRUM BRAKES This invention relates to drum brakes and in
particular to wheel cylinders for operating drum brakes.
There is a requirement to provide a simple, efficient and cheap to manufacture wheel cylinder which is also relatively light and capable of responding quickly to pressurisation. to operate the associated drum brake.
Thus according to the present invention there is provided a wheel cylinder comprising a sheet metal cylinder member arranged to contact an associated drum brake shoe and a sheet metal piston member in sealed sliding contact within the cylinder member and arranged to contact another associated drum brake shoe, the cylinder and piston members defining therebetween an actuating chamber into which pressurised fluid is introduced to displace the piston member relative to the cylinder member to force the associated brake shoes apart.
The above described wheel cylinder construction is particularly simple since it consists of only two basic parts with a single fluid pressure seal acting between the cylinder and piston members. Thus the construction is also relatively cheap to make. Also, the construction has the added advantage in that it only requires the use of one seal between the cylinder member and piston member therefore reducing any losses in brake pressure due to seal deflection on pressurisation of the fluid since conventional wheel cylinders have two seals and thus the present invention halves the pressure losses due to seal deflection. This is a particularly important advantage in modem braking systems which are required to be as stiff as possible to give the necessary quick response since they often form part of anti-lock or traction control systems etc.
Preferably in the present invention the sheet metal cylinder member and piston member is produced by a cold forming process such as, for example, by deep drawing or pressing. This provides a particularly cheap but efficient construction.
2 Preferably a spring acts between the cylinder and piston members to bias the members apart into contact with their respective associated brake shoes. Conveniently this spring is outside the actuating chamber.
The closed end of the cylinder member may have a depression or other formation to locate the cylinder member relative to the associated brake shoe. Similarly, a portion of the piston member may also be shaped to locate the piston member relative to the associated brake shoe.
Conveniently, the piston may carry the fluid pressure seal, for example, on a reduced diameter portion of the piston member to seal the actuating chamber.
A dust seal may be provided between the cylinder member and piston member to exclude dust and other contaminants. A bellows may also be provided between the cylinder member and piston member to exclude dust and other contaminants as an alternative to or in addition to the dust seal.
The inlet into the actuating chamber may comprise a short length of rigid tubing welded or otherwise secured to the cylinder member with a flexible pipe connected to the figid tubing to allow movement of the wheel cylinder relative to a back plate or other support on which the associated brake shoes are mounted.
The present invention also provides a drum brake including a wheel cylinder of the form described above acting between adjacent ends of associated brake shoes.
The invention further provides a drum brake having a wheel cylinder supported between the adjacent ends of a pair of brake shoes, the wheel cylinder being supported totally from the brake shoes.
Such a drum brake in which the wheel cylinder is free to float supported totally on the ends of the shoes enables a non-structural backplate to be used. The two part wheel cylinder 3 construction described above is particularly suitable for use in such a drum brake. Such a drum brake has a flexible brake hose connection with its wheel cylinder to allow movement of the wheel cylinder relative to any backplate or other support structure on which the shoes are mounted.
One embodiment of the present invention will now be described by way of example only, with reference to the accompanying drawings in which:
Figure I shows a side view of part of a drum brake which includes a wheel cylinder in accordance with the present invention, Figure 2 shows a fragmentary view in the direction of arrow A of Figure 1, and Figure 3 shows an alternative fi7agmentary view in the direction of arrow A.
Referring to figure I this shows a drum brake 10 in which a pair of brake shoes I I and 12 are supported on a backplate 13 in the normal manner and have their ends I I a and 12a reacting against a backplate supported abutment 13 a. Between the other ends I I b and 12b of the brake shoes is provided a wheel cylinder 14 in accordance with the present invention which comprises a sheet metal cylinder member 15 within which a sheet metal piston member 16 is slideable both preferably produced by a cold fbrn-ing process such as, for example, deep drawing or pressing. Cylinder member 15 has a depression 17 which locates the wheel cylinder relative to the end I I b of brake shoe 11. Similarly piston member 16 is belled at 18 to accept a cup 32 which locates on the end 12b of brake shoe 12. Cup 32 may be welded or otherwise permanently secured to piston 16. Alternatively the end of the brake shoe 12 may act on piston 16 directly. The wheel cylinder 14 is thus supported totally from the end I I b and 12b of the brake shoes.
Piston member 16 carries a seal 19 on a reduced diameter portion 20. The seal defines an actuating chamber 21 into which pressurise hydraulic fluid may be introduced from an associated master cylinder (not shown) via an inlet comprising a rigid pipe 22 (shown in 4 Figure 2) welded onto cylinder member 15 to which is attached a flexible brake hose 23 which allows the wheel cylinder to move relative to the backplate 13 on which the brake shoes I I and 12 are supported. This movement of the wheel cylinder 14 relative to the backplate 13 is accommodated by slot 33 in the backplate which may be sealed by a suitable bellows around hose 23. A coil spring 24 acts between the cylinder member 15 and piston member 16 to tend to increase the effective length of the wheel cylinder to ensure that the wheel cylinder remains in contact with the ends I lb and 12b of the associated brake shoes. A bellows 25 is provided which acts between the piston member 16 and the cylinder member 15 to prevent the ingress of dust and other contaminants into the wheel cylinder. If desired the bellows 25 may be augmented by a dust seal 25a (see Figure 3) or alternatively the dust seal 25a could replace the beUows 25 as shown in Figure 3.
Brake shoe return springs 26 act between the shoes 11 and 12 in the conventional manner and a hand brake operating lever 27 pivotted on shoe 12 at 28 is actuated by a cable 29 and operates shoe I I via a conventional strut 30 which may include a brake shoe wear adjuster.
The wheel cylinder arrangement described above operates as follows. To apply the brake shoes I I and 12 against the associated brake drum (indicated diagrammatically by dotted line 3 1) the actuating chamber 21 is pressurised via hose 23 and inlet tube 22 this displaces piston member 16 relative to cylinder member 15 to increase the effective length of the wheel cylinder 14 and hence displace the ends I lb and 12b of the associated brake shoes away from each other to apply the shoes against the brake drum in the normal manner.
As previously indicated, the wheel cylinder construction described above is particularly simple and efficient in operation and also cheap to manufacture and therefore meets the modem requirements of braking system manufacturers.
A2592

Claims (12)

1. A wheel cylinder comprising a sheet metal cylinder member arranged to contact an associated drum brake shoe and a sheet metal piston member in sealed sliding contact within the cylinder member and arranged to contact another associated drum brake shoe, the cylinder and piston members defining therebetween an actuating chamber into which pressurised fluid is introduced to displace the piston member relative to the cylinder member to force the associated brake shoes apart.
2. A wheel cylinder according to claim I in which a spring acts between the cylinder and piston members to bias the members apart for contact with their associated brake shoes.
3. A wheel cylinder according to any one of claim I or 2 in which the cylinder member and piston member both have locating formations for the support of the wheel cylinder on the associated brake shoes.
4. A wheel cylinder according to any one of claims I to 3 in which a fluid seal is carried on a reduced diameter portion of the piston member to seal the actuating chamber.
5. A wheel cylinder according to any one of claims I to 4 in which a dust seal is provided between the cylinder member and piston member to exclude dust and other contaminants.
6. A wheel cylinder according to any one of claims I to 5 in which a bellows is provided between the cylinder member and piston member to exclude dust and other contaminants,
7. A wheel cylinder according to any one of claims I to 6 in which the piston member 6 comprises a sheet metal main piston member closed at one end by a cup member which contacts the associate brake shoe.
8. A wheel cylinder according to any one of claims I to 7 in which the inlet to the actuating chamber is via a length of flexible pipe which allows movement of the wheel cylinder relative to any backplate or other support on which the associated brake shoes are mounted.
9. A drum brake including a wheel cylinder according to any one of claims I to 8.
10. A drum brake having a wheel cylinder supported between the adjacent ends of a pair of brake shoes, the wheel cylinder being supported totally from the brake shoes.
11. A drum brake according to claim 10 in which the wheel cylinder is in accordance with any one of claims I to 8.
12. A wheel cylinder constructed and arranged substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
GB9907995A 1998-04-14 1999-04-08 Drum bakes Expired - Fee Related GB2339868B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GBGB9807716.7A GB9807716D0 (en) 1998-04-14 1998-04-14 Drum brakes

Publications (3)

Publication Number Publication Date
GB9907995D0 GB9907995D0 (en) 1999-06-02
GB2339868A true GB2339868A (en) 2000-02-09
GB2339868B GB2339868B (en) 2002-06-26

Family

ID=10830177

Family Applications (2)

Application Number Title Priority Date Filing Date
GBGB9807716.7A Ceased GB9807716D0 (en) 1998-04-14 1998-04-14 Drum brakes
GB9907995A Expired - Fee Related GB2339868B (en) 1998-04-14 1999-04-08 Drum bakes

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GBGB9807716.7A Ceased GB9807716D0 (en) 1998-04-14 1998-04-14 Drum brakes

Country Status (1)

Country Link
GB (2) GB9807716D0 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2849135A1 (en) * 2002-12-20 2004-06-25 Bosch Gmbh Robert Vehicle wheel brake cylinder, has elastic unit for operating piston and maintaining contact between piston and unit connected to friction lining, when cylinder body does not contain liquid
WO2010043324A1 (en) * 2008-10-15 2010-04-22 Knorr-Bremse Systeme für Schienenfahrzeuge GmbH Pneumatic brake cylinder

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1100418A (en) * 1966-11-15 1968-01-24 Zentralinstitut Fur Fertigunst Double walled cylinders
EP0089267A2 (en) * 1982-03-12 1983-09-21 The Bendix Corporation A wheel cylinder for a drum brake

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1100418A (en) * 1966-11-15 1968-01-24 Zentralinstitut Fur Fertigunst Double walled cylinders
EP0089267A2 (en) * 1982-03-12 1983-09-21 The Bendix Corporation A wheel cylinder for a drum brake

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2849135A1 (en) * 2002-12-20 2004-06-25 Bosch Gmbh Robert Vehicle wheel brake cylinder, has elastic unit for operating piston and maintaining contact between piston and unit connected to friction lining, when cylinder body does not contain liquid
WO2010043324A1 (en) * 2008-10-15 2010-04-22 Knorr-Bremse Systeme für Schienenfahrzeuge GmbH Pneumatic brake cylinder
US8826801B2 (en) 2008-10-15 2014-09-09 Knorr-Bremse Systeme Fur Schienenfahrzeuge Gmbh Pneumatic brake cylinder

Also Published As

Publication number Publication date
GB2339868B (en) 2002-06-26
GB9807716D0 (en) 1998-06-10
GB9907995D0 (en) 1999-06-02

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Legal Events

Date Code Title Description
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20150408