GB1576156A - Fluid pressure actuator - Google Patents

Fluid pressure actuator Download PDF

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Publication number
GB1576156A
GB1576156A GB4994177A GB4994177A GB1576156A GB 1576156 A GB1576156 A GB 1576156A GB 4994177 A GB4994177 A GB 4994177A GB 4994177 A GB4994177 A GB 4994177A GB 1576156 A GB1576156 A GB 1576156A
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GB
United Kingdom
Prior art keywords
piston
fluid pressure
piston portion
metallic
sealing surface
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.)
Expired
Application number
GB4994177A
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.)
Bendix Corp
Original Assignee
Bendix Corp
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 Bendix Corp filed Critical Bendix Corp
Publication of GB1576156A publication Critical patent/GB1576156A/en
Expired legal-status Critical Current

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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
    • F16D65/00—Parts or details
    • F16D65/14—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position
    • 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
    • F16D65/78—Features relating to cooling
    • F16D2065/785—Heat insulation or reflection
    • 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

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

Description

(54) FLUID PRESSURE ACTUATOR (71) We, THE BENDIX CORPORA TION, a corporation organised and existing under the laws of the State of Delaware, United States of America, of Executive Offices, Bendix Center, Southfield, Michigan, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a fluid pressure actuator, and particularly to an actuator for the brake of an aircraft or of an automotive vehicle.
All the known prior art provides some metal-to-metal contact between the sliding surfaces of the piston and of the housing forming the actuator. This metal-to-metal contact induces fast wear of the actuator components and subsequent seal leakage.
This drawback is particularly cumbersome in the aircraft brakes which use multiple fric tional surfaces and in which it is desired to have the actuator perform as long as the fric tional material, without maintenance.
However, the known actuators present the advantage that the sealing means which are provided between the piston and the housing are very effective because of the cooperation of the sealing means with metallic sealing surfaces.
The object of the present invention is to eliminate the metal-to-metal sliding surfaces, and thereby to decrease wear and to increase the operable life of the actuator, while retain ing the quality of fluid seal obtained with the known actuators. Although this result is par ticularly useful in the aircraft brakes, the -invention is not limited to this field.
According to the present invention there is provided a fluid pressure actuator compris ing: a housing having a cavity therein, said cav ity having at least one closed end and the bore of said cavity defining a first fluid pressure sealing surface; a first piston located in said bore and cooperating with said housing to define a pressure chamber in said cavity, said first piston having a peripheral non-metallic surface directly engaging said first fluid pressure sealing surface in said metallic cylindrical member, said non-metallic peripheral surface attenuating wear of said metallic first fluid pressure sealing surface, said first piston having a first face located in said bore and a second face located outside said housing; a second metallic piston located in said pressure chamber having a first diameter section separated from a second diameter section by a first shoulder and a third diameter section separated from said second diameter section by a second shoulder, said first diameter section being smaller than said first fluid pressure sealing surface, said second diameter section being smaller than said first diameter section, and said third diameter section being smaller than said second diameter section; fastener means for holding said second diameter section of said metallic piston against said first face of said first piston to establish a second sealing surface on said second diameter section and a third sealing surface on said first face, said fastener means said third diameter section and said first piston cooperating to hold said first diameter section of said metallic piston concentric to said bore to prevent the first diameter section from contacting said first fluid pressure sealing surface; and sealing means located between said first and second fluid pressure sealing surfaces, said sealing means responding to fluid pressure in said pressure chamber by moving into engagement with said third sealing surface and thereafter being compressed to radially expand into a fluid-tight engagement with said first and second fluid pressure sealing surfaces to prevent fluid from being communicated from said pressure chamber through said bore.
The invention will be now described, by way of example, with reference to the accompanying drawing in which the sole figure is a sectional view of a hydraulic actuator adapted to be used in an aircraft brake.
Referring to the Figure, numeral 10 designates a piston housing, or cylinder, defining a cavity 12 therewithin. A fluid port 13 provided in the housing 10 allows pressurized fluid into cavity 12 from a controlled source, not shown. Cavity 12 is provided with a sleeve 14 threadedly engaged with housing 10 and provided with an annular recess containing an "0" ring or similar fluid seal 16.
Sleeve 14 is composed of a conventional metal suitable to provide a good fluid pressure sealing surface and which is hereinafter referred to or the first fluid pressure sealing surface. Sleeve 14 also has a flange portion 18 adapted to be engaged by wrench means, not shown, for assembly and disassembly purposes. Although the described embodiment comprises a sleeve 14, it can be deleted without departing from the scope of the invention. Indeed, conventional brake actuators have metal-to-metal contact which wear out the fluid pressure sealing surface, and it is much easier to replace a sleeve 14 than the housing 10. The present invention eliminates the metal-to-metal contact and thereby substantially reduces wear on the fluid pressure sealing surface. This reduced wear enables the inside surface of the housing 10 to be adapted to provide the metallic fluid pressure sealing surface thereby omitting sleeve 14.
A pressure responsive piston is composed of two parts defining an outer piston portion 20, which is composed of a non-metallic substance, and an inner piston portion 22, which is composed of a conventional metal suitable for fluid pressure sealing surfaces. The outer piston portion 20 has an outside diameter sufficient to allow its cylindrical external surface to slidably engage the cylindrical inside surface of sleeve 14. The inner piston portion 22 has an outside diameter which is smaller than the outside diameter of the outer piston portion 20. Piston portions 20 and 22 are coaxially secured together by a screw 24 threaded into the piston portion 22. To maintain the coaxial position of piston portion 22 to piston portion 20, piston portion 22 has a cylindrical coaxial extension 28 received in a cylindrical hold 30 provided in the outer piston portion 20. This coaxial arrangement and the smaller diameter of piston portion 22 provide a cylindrical gap 26 between the outer surface of piston portion 22 and the inner surface of sleeve 14.
A fluid seal recess is formed by an annular fluid sealing surface 32 piston portion 22 which is hereinafter referred to as the second fluid pressure sealing surface and a fluid pressure seal stop 36 which is hereinafter referred to as the third fluid pressure sealing surface. The stop 36 is defined by a portion of the rearward annular surface area of piston portion 20 which is exposed due to the difference in diameters between piston portion 20 and annular surface 32 provided on piston portion 22. The fluid seal recess defined by the annular surface 32 and by the stop 36 receives a fluid seal or "0" ring 38 and a back-up ring 40 disposed between the seal 38 and the surface area formed by the stop 36.
The use of back-up rings, co-termed as nonextrusion rings, is well known in the art and is necessary at high fluid pressure to prevent the "0" ring from being squeezed into the small space between the slidably engaged surfaces of piston portion 20 and sleeve 14.
Although not necessary for the operation of the described seal assembly, the piston portion 22 is provided with an annular shoulder 34 which retains the O-ring 38 and back-up ring 40 during installation and removal.
An abrasion shield 42 is used to separate ths piston portion 20 from a pressure plate 44 because of the heat developed during braking. Shield 42 is held in place by the screw 24 and acts as an insulator to retard heat transfer into piston portion 20. The piston portion 20 only bears against the pressure plate 44 during operation in the referenced aircraft disc brake environment.
Many other piston configurations are possible without deviating from the present.
invention as recited in the claims. For example, piston portion 22 can be secured to piston portion 20 in various ways to ensure a non-engagement of the metallic surfaces.
Both piston portions may be non-metallic so long as the annular fluid sealing surface 32 is metallic. The piston assembly can also be constructed from a single piston portion.
Furthermore, piston portion 20 does not have to be entirely non-metallic, it only needs a non-metallic surface engaged with sleeve 14. Finally, as already mentioned, the sleeve 14 can be removed and the piston assembly received directly in the housing 10 without departing from the scope of the invention.
WHAT WE CLAIM IS: 1. A fluid pressure actuator comprising: a housing having a cavity therein, said cavity having at least one closed end and the bore of said cavity defining a first fluid pressure sealing surface; a first piston located in said bore and cooperating with said housing to define a pressure chamber in said cavity, said first piston having a peripheral non-metallic surface directly engaging said first fluid pressure sealing surface in said metallic cylindrical member, said non-metallic peripheral sur
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. surfaces to prevent fluid from being communicated from said pressure chamber through said bore. The invention will be now described, by way of example, with reference to the accompanying drawing in which the sole figure is a sectional view of a hydraulic actuator adapted to be used in an aircraft brake. Referring to the Figure, numeral 10 designates a piston housing, or cylinder, defining a cavity 12 therewithin. A fluid port 13 provided in the housing 10 allows pressurized fluid into cavity 12 from a controlled source, not shown. Cavity 12 is provided with a sleeve 14 threadedly engaged with housing 10 and provided with an annular recess containing an "0" ring or similar fluid seal 16. Sleeve 14 is composed of a conventional metal suitable to provide a good fluid pressure sealing surface and which is hereinafter referred to or the first fluid pressure sealing surface. Sleeve 14 also has a flange portion 18 adapted to be engaged by wrench means, not shown, for assembly and disassembly purposes. Although the described embodiment comprises a sleeve 14, it can be deleted without departing from the scope of the invention. Indeed, conventional brake actuators have metal-to-metal contact which wear out the fluid pressure sealing surface, and it is much easier to replace a sleeve 14 than the housing 10. The present invention eliminates the metal-to-metal contact and thereby substantially reduces wear on the fluid pressure sealing surface. This reduced wear enables the inside surface of the housing 10 to be adapted to provide the metallic fluid pressure sealing surface thereby omitting sleeve 14. A pressure responsive piston is composed of two parts defining an outer piston portion 20, which is composed of a non-metallic substance, and an inner piston portion 22, which is composed of a conventional metal suitable for fluid pressure sealing surfaces. The outer piston portion 20 has an outside diameter sufficient to allow its cylindrical external surface to slidably engage the cylindrical inside surface of sleeve 14. The inner piston portion 22 has an outside diameter which is smaller than the outside diameter of the outer piston portion 20. Piston portions 20 and 22 are coaxially secured together by a screw 24 threaded into the piston portion 22. To maintain the coaxial position of piston portion 22 to piston portion 20, piston portion 22 has a cylindrical coaxial extension 28 received in a cylindrical hold 30 provided in the outer piston portion 20. This coaxial arrangement and the smaller diameter of piston portion 22 provide a cylindrical gap 26 between the outer surface of piston portion 22 and the inner surface of sleeve 14. A fluid seal recess is formed by an annular fluid sealing surface 32 piston portion 22 which is hereinafter referred to as the second fluid pressure sealing surface and a fluid pressure seal stop 36 which is hereinafter referred to as the third fluid pressure sealing surface. The stop 36 is defined by a portion of the rearward annular surface area of piston portion 20 which is exposed due to the difference in diameters between piston portion 20 and annular surface 32 provided on piston portion 22. The fluid seal recess defined by the annular surface 32 and by the stop 36 receives a fluid seal or "0" ring 38 and a back-up ring 40 disposed between the seal 38 and the surface area formed by the stop 36. The use of back-up rings, co-termed as nonextrusion rings, is well known in the art and is necessary at high fluid pressure to prevent the "0" ring from being squeezed into the small space between the slidably engaged surfaces of piston portion 20 and sleeve 14. Although not necessary for the operation of the described seal assembly, the piston portion 22 is provided with an annular shoulder 34 which retains the O-ring 38 and back-up ring 40 during installation and removal. An abrasion shield 42 is used to separate ths piston portion 20 from a pressure plate 44 because of the heat developed during braking. Shield 42 is held in place by the screw 24 and acts as an insulator to retard heat transfer into piston portion 20. The piston portion 20 only bears against the pressure plate 44 during operation in the referenced aircraft disc brake environment. Many other piston configurations are possible without deviating from the present. invention as recited in the claims. For example, piston portion 22 can be secured to piston portion 20 in various ways to ensure a non-engagement of the metallic surfaces. Both piston portions may be non-metallic so long as the annular fluid sealing surface 32 is metallic. The piston assembly can also be constructed from a single piston portion. Furthermore, piston portion 20 does not have to be entirely non-metallic, it only needs a non-metallic surface engaged with sleeve 14. Finally, as already mentioned, the sleeve 14 can be removed and the piston assembly received directly in the housing 10 without departing from the scope of the invention. WHAT WE CLAIM IS:
1. A fluid pressure actuator comprising: a housing having a cavity therein, said cavity having at least one closed end and the bore of said cavity defining a first fluid pressure sealing surface; a first piston located in said bore and cooperating with said housing to define a pressure chamber in said cavity, said first piston having a peripheral non-metallic surface directly engaging said first fluid pressure sealing surface in said metallic cylindrical member, said non-metallic peripheral sur
face attenuating wear of said metallic first fluid pressure sealing surface, said first piston having a first face located in said bore and a second face located outside said housing; a second metallic piston located in said pressure chamber having a first diameter section separated from a second diameter section by a first shoulder and a third diameter section separated from said second diameter section by a second shoulder, said first diameter section being smaller than said first fluid pressure sealing surface, said second diameter section being smaller than said first diameter section, and said third diameter section being smaller than said second diameter section; fastener means for holding said second diameter section of said metallic piston against said first face of said first piston to establish a second sealing surface on said second diameter section and a third sealing surface on said first face, said fastener means said third diameter section and said first piston cooperating to hold said first diameter section of said metallic piston concentric to said bore to prevent the first diameter section from contacting said first fluid pressure sealing surface; and sealing means located between said first and second fluid pressure sealing surfaces said sealing means responding to fluid pressure in said pressure chamber by moving into engagement with said third sealing surface and thereafter being compressed to radially expand into a fluid-tight engagement with said first and second fluid pressure sealing surfaces to prevent fluid form being communicated from said pressure chamber through said bore.
2. A fluid pressure actuator as claimed in Claim 1, wherein the third diameter section of the second metallic piston comprises a cylindrical abutment extending into a cavity in the first piston, and a screw member passes through said first piston into said cylindrical abutment to secure said pistons fixedly together thereby maintaining a force transmitting relationship therebetween.
3. A fluid pressure actuator as claimed in either of the preceding claims, wherein a metallic cylindrical member is fixed to said housing and extends into the cavity therein, said cylindrical member having a bore defining the first fluid pressure sealing surface.
4. A fluid pressure actuator as claimed in any of the preceding claims, wherein the first piston is entirely metallic.
5. A fluid pressure actuator substantially as described and a shown in the accompanying drawings.
GB4994177A 1976-12-20 1977-11-30 Fluid pressure actuator Expired GB1576156A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US75236676A 1976-12-20 1976-12-20

Publications (1)

Publication Number Publication Date
GB1576156A true GB1576156A (en) 1980-10-01

Family

ID=25026014

Family Applications (1)

Application Number Title Priority Date Filing Date
GB4994177A Expired GB1576156A (en) 1976-12-20 1977-11-30 Fluid pressure actuator

Country Status (5)

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JP (1) JPS5377973A (en)
DE (1) DE2755815A1 (en)
FR (1) FR2374559A1 (en)
GB (1) GB1576156A (en)
IT (1) IT1088790B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2867243A1 (en) * 2004-03-02 2005-09-09 Bosch Gmbh Robert Disc brake caliper for braking system of motor vehicle, has return joint housed in groove arranged in hydraulic actuator body having groove tread which extends from hydraulic chamber, containing hydraulic oil, to groove

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3323361A1 (en) * 1983-06-29 1985-04-04 Alfred Teves Gmbh, 6000 Frankfurt Piston-cylinder arrangement for brakes
DE10162527A1 (en) * 2001-12-19 2003-07-10 Rexroth Mecman Gmbh Pressure cylinder with a positively attached cylinder cover

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB700644A (en) * 1952-10-11 1953-12-09 Girling Ltd Improvements in or relating to disc brakes for vehicles
FR1170537A (en) * 1956-04-02 1959-01-15 Bendix Aviat Corp Disc brake development
US2801714A (en) * 1956-06-29 1957-08-06 Meadville Res Products Corp Heat insulating friction shoe and piston unit
US3251437A (en) * 1964-04-13 1966-05-17 Bendix Corp Air cooled disk brake
FR1424951A (en) * 1965-02-18 1966-01-14 Lambert & Brake Corp Expansion chamber brake
FR1484290A (en) * 1965-06-23 1967-06-09 Bendix Corp Control device for disc brakes
US3675742A (en) * 1970-04-16 1972-07-11 Tom H Thompson Disc brake caliper assembly
US3675743A (en) * 1970-07-30 1972-07-11 Tom H Thompson Hydraulic disc brake construction
US4147241A (en) * 1977-10-27 1979-04-03 The Bendix Corporation Structurally strong heat insulator for high transient temperatures

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2867243A1 (en) * 2004-03-02 2005-09-09 Bosch Gmbh Robert Disc brake caliper for braking system of motor vehicle, has return joint housed in groove arranged in hydraulic actuator body having groove tread which extends from hydraulic chamber, containing hydraulic oil, to groove

Also Published As

Publication number Publication date
JPS5377973A (en) 1978-07-10
FR2374559A1 (en) 1978-07-13
IT1088790B (en) 1985-06-10
DE2755815A1 (en) 1978-06-22

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CSNS Application of which complete specification have been accepted and published, but patent is not sealed