GB2183747A - Piston and cylinder assembly including a seal arrangement - Google Patents
Piston and cylinder assembly including a seal arrangement Download PDFInfo
- Publication number
- GB2183747A GB2183747A GB08627626A GB8627626A GB2183747A GB 2183747 A GB2183747 A GB 2183747A GB 08627626 A GB08627626 A GB 08627626A GB 8627626 A GB8627626 A GB 8627626A GB 2183747 A GB2183747 A GB 2183747A
- Authority
- GB
- United Kingdom
- Prior art keywords
- piston
- sealing ring
- ring cup
- sealing lip
- pressure chamber
- 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
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T11/00—Transmitting braking action from initiating means to ultimate brake actuator without power assistance or drive or where such assistance or drive is irrelevant
- B60T11/10—Transmitting braking action from initiating means to ultimate brake actuator without power assistance or drive or where such assistance or drive is irrelevant transmitting by fluid means, e.g. hydraulic
- B60T11/16—Master control, e.g. master cylinders
- B60T11/236—Piston sealing arrangements
Landscapes
- Engineering & Computer Science (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Transmission Of Braking Force In Braking Systems (AREA)
- Hydraulic Clutches, Magnetic Clutches, Fluid Clutches, And Fluid Joints (AREA)
Abstract
A piston and cylinder assembly, in particular for hydraulic actuating mechanisms in automotive vehicles, comprises a piston (4) guided in a cylinder housing (2) in a cylinder bore (3). The piston (4) is provided with an annular step (5), whereon a sealing ring cup (6) of a seal arrangement, having a U-shaped cross-section is arranged, which sealing ring cup has a radially inner sealing lip (17, 18) abutting on the annular step (5) and a radially outer sealing lip (17, 18) sliding in the cylinder bore (3). The master cylinder (1) is provided with a supply connection (16, 12, 10 and 23), permitting, in the event of a drop of pressure from a supply chamber (12) to a pressure chamber (29), a flow of pressure fluid into the pressure chamber (29) past the radially inner sealing lip (17), the inner sealing lip (17) being moved radially inwards by means of the pressure fluid. In order to achieve an optimal reduction of the idle travel occurring and a better mastery of the tolerances, the radially outer sealing lip (18) of the sealing ring cup (6) is guided in the cylinder bore (3) and bears against the spring plate (31) in axial direction, the sealing ring cup (6) is provided on its side directed away from the pressure chamber (29) with a circular recess (33) receiving the backing washer (13), and the supply connection is constituted by means of radially inner channels (10) running axially. <IMAGE>
Description
SPECIFICATION
Piston and cylinder assembly including a seal arrangement
The present invention relates to a piston and cylinder assembly including a seal arrangement, in particular for hydraulic actuating mechanisms in automotive vehicles, the assembly comprising a piston disposed in a cylinder housing in a cylinder bore, which piston is provided with a sealing ring cup, for sealing a pressure chamber relative to a supply chamber, in an annular groove on its peripheral surface, said sealing ring cup comprising a radially inner sealing lip abutting on the bottom of the annular groove and a radially outer sealing lip sliding in the cylinder bore, and abutting on which piston is a backing washer located on the piston's side wall directed away from the supply chamber, a supply connection leading from the supply chamber to the pressure chamber, which supply connection permits a recuperation of pressure fluid into the pressure chamber in the event that there is a drop of pressure from the supply chamber to the pressure chamber, and a spring plate which is pressed against a step provided at the piston.
A piston and cylinder assembly including a seal arrangement is known, for instance, from our prior West German patent application P 35 33 731. In this seal arrangement, the sealing ring cup separating the pressure chamber from the supply chamber in the cylinder and permitting a recuperation of pressure fluid via a radially outer sealing lip is arranged at the piston with inner axial elastic preload.
In a seal arrangement of this kind it is, however, considered less favourable that an axial displaceablility of the radially outer sealing lip of the sealing ring cup is required in order to guarantee a perfect functioning with regard to the recuperation process of the piston and cylinder assembly, said displaceability resulting, however, in a considerable idle travel which has a negative effect, above all, in the event of a pressure compensation after the hydraulic system has been relieved.
Another disadvantage of seal arrangements of this kind consists in that the elastic radially outer sealing lip may be pressed, under the effect of the axial force being generated during a pressure increase in the pressure chamber, into the annular gap between the piston and the wall of the cylinder bore such that the sealing ring cup is destroyed at the piston edge.
It is, therefore, an object of the present invention to create a piston and cylinder assembly including a seal arrangement of the type initially referred to, wherein the disadvantages of the known seal arrangement will be avoided to a large extent, which will allow for an optimal reduction the idle travel, and which will result in a better mastery of occurring tolerances.
According to the present invention there is provided a piston and cylinder assembly including a seal arrangement, in particular for hydraulic actuating mechanisms in automotive vehicles, the assembly comprising a piston disposed in a cylinder housing in a cylinder bore which piston is provided with a sealing ring cup for sealing a pressure chamber relative to a supply chamber, in an annular groove on its peripheral surface, said sealing ring cup comprising a radially inner sealing lip abutting on the bottom of the annular groove and a radially outer sealing lip sliding in the cylinder bore, and abutting on which piston is a backing washer located on the piston's side wall directed away from the supply chamber, a supply connection leading from the supply chamber to the pressure chamber, which supply connection permits a recuperation of pressure fluid into the pressure chamber in the event that there is a drop of pressure from the supply chamber to the pressure chamber, and a spring plate which is pressed against a stop provided at the piston, characterised in that the radially outer sealing lip of the sealing ring cup is guided in the cylinder bore and bears against the spring plate in the axial direction, in that the sealing ring cup is provided with a circular recess receiving the backing washer on its side directed away from the pressure chamber, and in that the supply connection is constituted by radially inner channels running axially.
In an embodiment of this kind, an efficient reduction of the idle travel between the edge of the radially outer sealing lip and the edge of the compensation port is advantageously achieved. Due to the relocation of the recuperation process into the radially inner area, the axial displaceability of the sealing ring cup required so far is omitted, the life of the seal arrangement being increased considerably by means of the solid, stiff outer sealing lip.
An advantageous embodiment provides that the diameter and the depth of the circular recess are larger than the diameter and the thickness of the backing washer. Thereby, free spaces are being generated both in the radial and in the axial direction which allow for movements of the backing washer, which movements contribute to a particularly efficient flow of the hydraulic fluid.
An improvement of the present invention provides that the backing washer has a plurality of radial cutouts situated on its radially inner edge. Due to this means, a perfect flow is guaranteed even in the event of high flow rates of the hydraulic fluid which may have the effect that the backing washer is pressed against the circular recess.
According to a particularly advantageous feature of the present invention, the sealing ring cup is, on its end face directed towards the pressure chamber, near the inner sealing lip, provided with a circumferential groove which serves to determine the tilting point of the radially inner sealing lip during the recuperation process in a defined way. In this case, the spring plate is provided with a plurality of axial projections directed towards the sealing ring cup, which projections prevent a folding down of the sealing ring cup during a rapid recuperation of hydraulic fluid.
According to another aspect of the present invention there is provided a seal arrangement, for use with a piston and cylinder assembly, comprising a sealing ring cup, for sealing a pressure chamber relative to a supply chamber, said sealing ring cup having a radially inner sealing lip, which in use abuts on the bottom of an annular groove provided on the peripheral surface of the piston, and a radially outer sealng lip which in use slides in a bore of the cylinder a backing washer which in use is located on a side wall of the piston directed away from the supply chamber, and a spring plate which in use is pressed against a step provided at the piston, characterised in that the radially outer sealing lip of the sealing ring cup bears against the spring plate in the axial direction, in that the sealing ring cup is provided with a circular recess, on its side which in use is directed away from the pressure chamber, for receiving the backing washer.
An embodiment of the present invention will now be described in more detail with reference to the accompanying drawing which shows a partial longitudinal section of a seal arrangement for a piston and cylinder assembly
The piston and- cylinder assembly comprises a master cylinder 1 and a cylinder housing 2, wherein a piston 4 is axially displaceably guided in a cylinder bore 3. The piston 4 is provided with an annular step 5, whereon a sealing ring cup 6 is arranged. At the sides, the annular step 5 is confined by means of a side wall 7, 8 respectively. The right-hand side wall 7, as shown in the drawing, is constituted by means of an annular collar 9 arranged at the piston 4.The annular collar 9 is, within its radially inner area, provided with channels 10 which are uniformly distributed and are running substantially parallel to the longitudinal axis 11 of the piston 4, and which commence in the supply chamber 12 formed on the right-hand side of the annular collar 9, as shown in the drawing, and adjoin a backing washer 13 abutting on the side wall 7 in the initial position of the master cylinder 1, said backing washer being provided with a plurality of radial cutouts 14 on its radially inner edge.
The supply chamber 12 is connected via a feed port 16 arranged within the cylinder housing 2 and extending into the cylinder bore 3 with a supply reservoir (not shown) and pressurised by atmospheric pressure. A radially inner elastic sealing lip 17 and a radially outer solid sealing lip 18 are extending from a, in the initial position of the arrangement, vertical end face 15 of the sealing ring cup 6 to the left, as shown in the drawing, in a manner such that the cross-section of the sealing ring cup 6 has the form of a horizontally arranged U, the open end being directed towards a spring plate 31. The radially outer peripheral surface 19 of the outer sealing lip 18 is slidingly guided on the wall of the cylinder bore 3.The left-hand end face 21 at the end of the radially outer sealng lip 18, as shown in the drawing, bears against the edge of the spring plate 31 in the axial direction.
The radially inner peripheral surface 22 of the radially inner sealing lip 17 is running parallel to and at a small distance from the cylindrical peripheral surface 20 of the annular step 5. During the recuperation process, the chamber 23 formed by the radially inner sealing lip 17 and the cylindrical peripheral surface 20 of the annular step 5 is connected with the supply chamber 12 via the channels 10. The supply chamber 12, the channels 10 and the chamber 23 constitute the supply connection of the master cylinder 1.
A peripheral surface 24 inwardly extending in a conical manner adjoins the radially inner peripheral surface 22 on the left, as shown in the drawing, the sealing edge of said peripheral surface 24 abutting pressure-tightly on the cylindrical peripheral surface 20 of the annular step 5. Adjacent the sealing edge 28 of the peripheral surface 24 is a side face 25 running at an angle of approximately 90 to the peripheral surface 24, the surface portion of said side face being part of a cone. The side face 25 is confined by means of a peripheral surface 26 also running in a conical manner, whose extension 37 running substantially parallel to the cylindrical peripheral surface ends in a circumferential groove 27 provided on the end face 38 of the sealing ring cup 6, which end face is directed towards the pressure chamber 29.
On the side directed towards the supply chamber 12 and/or the side wall 7 formed at the annular collar 9 of the piston 4, the end face 15 of the sealing ring cup 6 is provided with a circular recess 33 which serves to receive the backing washer 13. In order to guarantee a free flow of the hydraulic fluid from the supply chamber 12 into the pressure chamber 29, the axial displaceability of the backing washer 13 is achieved in that both the diameter and the depth of the recess 33 are larger than the outside diameter and the thickness of the backing washer 13.
In the depicted initial position of the master cylinder, the end face 21 at the end of the radially outer sealing lip 18 is arranged at a small distance 34 from the left edge of a compensation port 36, as shown in the drawing, said distance corresponding to the idle travel which enters into the actuating travel of the master cylinder 1 and must be as small as possible. In the initial positon of the master cylinder 1, the compensation port 36 connects the supply reservoir with the pressure chamber 29 arranged on the left-hand side of the end face 21 of the outer sealing lip 18, as shown in the drawing. The radially outer sealing lip 18 abuts pressure-tightly on the wall of the cylinder bore 3.
A smaller-diameter step 30, bearing against which is the spring plate 31, is shaped at the piston 4 on the left-hand side of the radially inner sealing lip 17, as shown in the drawing.
The spring plate 31, which is provided with a plurality of passages 39 in order to improve the recuperation process, is urged against the step 30 by means of a piston return spring 32 which abuts on the end face 40 on the side of the pressure chamber. The piston return spring 32 penetrates the pressure chamber 29 and abuts with its left end, which is not depicted in the drawing, on a closed end of the cylinder bore 3, which is also not depicted in the drawing. In the case of a tandem master cylinder, the piston return spring 32 bears against a floating piston, which is not depicted in the drawing, in a primary circuit.
The pressure chamber 29 is connected via a pressure fluid conduit, which is not depicted in the drawing, with one or a plurality of hydraulic brake cylinders, for instance, slave cylinders of brakes or a slave cylinder of a clutch actuating mechanism.
The mode of operation of the seal arrangement according to the invention is as follows:
When the master cylinder is in the initial position, the compensation port 36 connects the pressure chamber 29 with the supply reservoir mentioned above. By this means, the pressure chamber 29 is unpressurised when the piston 4 is in its initial position, and pressure fluid may flow from the supply reservoir into the pressure chamber 29.
On actuating the piston 4 to the left, as shown in the drawing, the radially outer sealing lip 18 covers the compensation port 36.
When the piston 4 is further actuated, a pressure can only be built up in the pressure chamber 29, said pressure being transmitted to one or a plurality of slave cylinders via a pressure conduit. The pressure built up in the pressure chamber 29 urges the radially inner sealing lip 17 into the chamber 23, the pressing power depending on the amount of the hydraulic pressure. The higher the hydraulic pressure is in the pressure chamber 29, the stronger the radially outer sealing lip 18 is pressed against the wall of the cylinder bore 3 and the radially inner sealing lip 17 against the peripheral surface 20 of the annular step 5 at the piston 4.
On releasing the master cylinder 1, i.e.
when the piston 4 moves to the right, as shown in the drawing, the pressure in the pressure chamber 29 is reduced according to the movement of the piston 4. In the event that a vacuum is created in the pressure chamber 29 during a bleeding operation or due to an increased travel or wear at the wheel brakes or at the clutch before the compensation port 36 has been covered by the end face 21 of the outer sealing lip 18, the radially inner sealing lip 17 of the sealing ring cup 6 can move in radial direction, as shown in the drawing. The backing washer 13 then lifts off the side wall 7 of the annular collar 9.
A pressure fluid connection now exists from the supply chamber 12 via the channels 10 and the annular gap formed between the backing washer 13 and the side wall 7 to the chamber 23. The drop of pressure exerts a force on the radially inner sealing lip 17, which force is directed perpendicularly to the longitudinal axis 11 of the piston 4 and causes the inner sealing lip 17 to swing radially inwards about a hypothetical centre of rotation which is determined by the circumferential groove 23. Hereby, the radially inner sealing lip 17 lifts off the peripheral surface 20 of the annular step 5, thus generating a supply connection from the supply chamber 12 to the pressure chamber 29.Upon completion of the recuperation process, the radially outer sealing lip 18 again covers the compensation port 36, and additional pressure fluid can flow into the pressure chamber 29 via the compensation port 36 if the recuperation process has yet not been completed.
Due to the fact that in the seal arrangement according to the invention, an axial movability of the sealing ring cup 6 which is entrained by the movements of the piston 4 is not required, the piston 4 must thus not perform an idle travel in order to return the sealing ring cup 6 to its initial posiiton. During a subsequent actuation of the master cylinder 1, a pressure can thus be built up in the pressure chamber 29 immediately after the compensation port 36 has been covered. The idle travel existing in the master cylinder 1 is determined both by the thermal expansion behaviour of the master cylinder assembly and by the sum of all axial work tolerances of cups, piston and housing.
Claims (7)
1. a piston and cylinder assembly including a seal arrangement, in particular for hydraulic actuating mechanisms in automotive vehicles, the assembly comprising a piston disposed in a cylinder housing in a cylinder bore, which piston is provided with a sealing ring cup, for sealing a pressure chamber relative to a supply chamber, in an annular groove on its peripheral surface, said sealing ring cup comprising a radially inner sealing lip abutting on the bottom of the annular groove and a radially outer sealing lip sliding in the cylinder bore, and abutting on which piston is a backing washer located on the piston's side wall di rected away from the supply chamber, a supply connection leading from the supply chamber to the pressure chamber, which supply connection permits a recuperation of pressure fluid into the pressure chamber in the event that there is a drop of pressure from the supply chamber to the pressure chamber, and a spring plate which is pressed against a stop provided at the piston, characterised in that the radially outer sealing lip (18) of the sealing ring cup (6) is guided in the cylinder bore (3) and bears against the spring plate (31) in the axial direction, in that the sealing ring cup (6) is provided with a circular recess (33) receiving the backing washer (13) on its side directed away from the pressure chamber (29), and in that the supply connection is constituted by radially inner channels (10) running axially.
2. An assembly according to claim 1, characterised in that the diameter and the depth of the circular recess (33) are larger than the diameter and the thickness of the backing washer (13).
3. An assembly according to claim 1, characterised in that the axial length of the inner sealing lip (17) is smaller than that of the radially outer sealing lip (18).
4. An assembly according to any one of the preceding claims, characterised in that the spring plate (31) is provided with a plurality of axial projections (35) which are directed towards the sealing ring cup (6).
5. An assembly according to any one of the preceding claims, characterised in that the backing washer (13) is provided with a plurality of radial cutouts (14) situated on its radially inner edge.
6. A piston and cylinder assembly including a seal arrangement substantially as herein described with reference to and as illustrated in the accompanying drawing.
7. A seal arrangement, for use with a piston and cylinder assembly, comprising a sealing ring cup, for sealing pressure chamber relative to a supply chamber, said sealing ring cup having a radially inner sealing lip, which in use slides in a bore of the cylinder, a backing washer which in use abuts on the bottom of an annular groove provided on the peripheral surface of the piston, and a radially outer sealng lip which in use is located on a side wall of the piston directed away from the supply chamber, and a spring plate which in use is pressed against a step provided at the piston, characterised in that the radially outer sealing lip (18) of the sealing ring cup (6) bears against the spring plate (31) in the axial direction, in that the sealing ring cup (6) is provided with a circular recess (33), on its side which in use is directed away from the pressure chamber (29), for receiving the backing washer (13).
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19853542825 DE3542825A1 (en) | 1985-12-04 | 1985-12-04 | GASKET ARRANGEMENT FOR A PISTON CYLINDER UNIT |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8627626D0 GB8627626D0 (en) | 1986-12-17 |
| GB2183747A true GB2183747A (en) | 1987-06-10 |
| GB2183747B GB2183747B (en) | 1989-01-11 |
Family
ID=6287571
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08627626A Expired GB2183747B (en) | 1985-12-04 | 1986-11-19 | Piston and cylinder assembly including a seal arrangement |
Country Status (3)
| Country | Link |
|---|---|
| DE (1) | DE3542825A1 (en) |
| FR (1) | FR2590957B1 (en) |
| GB (1) | GB2183747B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0416753A1 (en) * | 1989-08-25 | 1991-03-13 | Wabco Automotive U.K. Limited | Recuperation in master cylinder |
| WO1996015371A1 (en) * | 1994-11-11 | 1996-05-23 | Zimmer Vorhaus Klaus | Pump piston |
| FR2848961A1 (en) * | 2002-12-20 | 2004-06-25 | Bosch Gmbh Robert | Clutch master cylinder for vehicle e.g. automobile, has secondary tight joint cutting communication between tube and reservoir and backlash device disposed in tube by fixing cylinder surface to cover joint |
| EP2165897A1 (en) * | 2008-09-19 | 2010-03-24 | Nissin Kogyo Co., Ltd. | Cylinder apparatus |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4128470A1 (en) * | 1991-08-28 | 1993-03-04 | Teves Gmbh Alfred | Piston for master cylinder of vehicle brake - has integration of filter carrier and sleeve seal support into single component |
| DE4445859A1 (en) * | 1994-12-22 | 1996-06-27 | Teves Gmbh Alfred | Piston-casing unit with pressure chamber in casing recess |
| DE19603870A1 (en) * | 1996-02-03 | 1997-08-07 | Teves Gmbh Alfred | Actuator for hydraulic brake system of motor vehicle |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2254937A (en) * | 1939-05-20 | 1941-09-02 | Wagner Electric Corp | Master cylinder piston construction |
| US2973231A (en) * | 1958-05-26 | 1961-02-28 | Noel S Reynolds | Piston assembly for hydraulic brake master cylinder |
| FR1324762A (en) * | 1961-06-09 | 1963-04-19 | Dunlop Sa | Improvements to master cylinders, in particular for motor vehicles |
| DE1655353B2 (en) * | 1967-02-03 | 1973-10-18 | Alfred Teves Gmbh, 6000 Frankfurt | Piston for a master cylinder of a hydraulic brake system, in particular a motor vehicle brake system |
| FR1583844A (en) * | 1968-05-03 | 1969-12-05 | ||
| GB1467640A (en) * | 1973-11-07 | 1977-03-16 | Girling Ltd | Piston and seal assemblies |
| IT1034812B (en) * | 1975-04-03 | 1979-10-10 | Benditalia Spa | MASTER CYLINDER |
| DE2644571C2 (en) * | 1976-10-02 | 1983-03-17 | Alfred Teves Gmbh, 6000 Frankfurt | Sealing sleeve |
| IT1129546B (en) * | 1980-01-17 | 1986-06-04 | Benditalia Spa | MASTER CYLINDER, PARTICULARLY FOR BRAKING SYSTEMS FOR VEHICLES |
| DE8009474U1 (en) * | 1980-04-05 | 1980-07-03 | Fag Kugelfischer Georg Schaefer & Co, 8720 Schweinfurt | PISTON AND GASKET ARRANGEMENT FOR BRAKE HYDRAULIC UNITS |
| DE3241881A1 (en) * | 1982-11-12 | 1984-05-17 | Alfred Teves Gmbh, 6000 Frankfurt | TANDEM MAIN CYLINDERS FOR HYDRAULICALLY ACTUATED VEHICLE BRAKES |
| DE3244180A1 (en) * | 1982-11-30 | 1984-05-30 | Alfred Teves Gmbh, 6000 Frankfurt | Sealing sleeve |
| DE3533731A1 (en) * | 1985-09-21 | 1987-03-26 | Teves Gmbh Alfred | Sealing arrangement for a piston/cylinder unit |
-
1985
- 1985-12-04 DE DE19853542825 patent/DE3542825A1/en active Granted
-
1986
- 1986-11-19 GB GB08627626A patent/GB2183747B/en not_active Expired
- 1986-12-03 FR FR8616879A patent/FR2590957B1/en not_active Expired - Lifetime
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0416753A1 (en) * | 1989-08-25 | 1991-03-13 | Wabco Automotive U.K. Limited | Recuperation in master cylinder |
| WO1996015371A1 (en) * | 1994-11-11 | 1996-05-23 | Zimmer Vorhaus Klaus | Pump piston |
| FR2848961A1 (en) * | 2002-12-20 | 2004-06-25 | Bosch Gmbh Robert | Clutch master cylinder for vehicle e.g. automobile, has secondary tight joint cutting communication between tube and reservoir and backlash device disposed in tube by fixing cylinder surface to cover joint |
| WO2004056634A1 (en) * | 2002-12-20 | 2004-07-08 | Robert Bosch Gmbh | Master cylinder for a vehicle comprising a free-play reduction device |
| EP2165897A1 (en) * | 2008-09-19 | 2010-03-24 | Nissin Kogyo Co., Ltd. | Cylinder apparatus |
| CN101676586B (en) * | 2008-09-19 | 2012-07-18 | 日信工业株式会社 | Cylinder apparatus |
| US8347623B2 (en) | 2008-09-19 | 2013-01-08 | Nissin Kogyo Co., Ltd. | Cylinder apparatus |
| US8646269B2 (en) | 2008-09-19 | 2014-02-11 | Nissin Kogyo Co., Ltd. | Cylinder apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3542825A1 (en) | 1987-06-11 |
| FR2590957B1 (en) | 1990-06-15 |
| GB8627626D0 (en) | 1986-12-17 |
| FR2590957A1 (en) | 1987-06-05 |
| DE3542825C2 (en) | 1993-04-22 |
| GB2183747B (en) | 1989-01-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20001119 |