GB2151705A - Variable-delivery sliding-vane rotary pump - Google Patents
Variable-delivery sliding-vane rotary pump Download PDFInfo
- Publication number
- GB2151705A GB2151705A GB08430974A GB8430974A GB2151705A GB 2151705 A GB2151705 A GB 2151705A GB 08430974 A GB08430974 A GB 08430974A GB 8430974 A GB8430974 A GB 8430974A GB 2151705 A GB2151705 A GB 2151705A
- Authority
- GB
- United Kingdom
- Prior art keywords
- pressure
- relief valve
- control apparatus
- valve
- pump
- 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
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C14/00—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations
- F04C14/18—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by varying the volume of the working chamber
- F04C14/22—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by varying the volume of the working chamber by changing the eccentricity between cooperating members
- F04C14/223—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by varying the volume of the working chamber by changing the eccentricity between cooperating members using a movable cam
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Details And Applications Of Rotary Liquid Pumps (AREA)
- Rotary Pumps (AREA)
- Reciprocating Pumps (AREA)
Abstract
The pump (1) is furnished with a movable cam-ring (4), a positioning piston-and-cylinder unit (7) on one side of said ring and a control piston-and-cylinder unit (9) on the opposite side, the pressure chambers of these units being linked to the pressure line (12) of the pump via lines (13 and 14). A flow-restricting orifice (15) is provided in the line (14) and a pressure-relief valve (18) is connected between the latter and an unpressurised tank (17). The pressure-relief valve is controlled by a pressure-responsive electric sensor (19) in accordance with a desired pressure- relief valve characteristic-curve, preferably having a descending slope. A comparator (21) may be disposed between the sensor and the pressure- relief valve in order that control is initiated only when a given pressure has been reached. <IMAGE>
Description
SPECIFICATION
Pressure control apparatus for a hydraulic pump, in particular for a vane pump
The present invention is related to a pressure control apparatus for a hydraulic pump, in particular for a vane pump, with a positioning piston-and-cylinder unit and a control piston-and-cylinder unit whose cylinder chambers are linked to a consumer pressure line of the hydraulic pump and whose pistons engage on opposite sides of an adjusting element, in particular a stroke ring of a vane pump, influencing the delivery rate of the pump, the positioning piston having an area smaller than that of the control piston which is spring-loaded in the direction of the maximum delivery rate of the hydraulic pump, and with an orifice configured in a section of the pressure line leading to the control piston-and-cylinder unit, a pressure relief valve furnished with a port toward an unpressurised tank being connected between the orifice and the control piston-and-cylinder unit.
In a known pressure control apparatus for a hydraulic pump, in particular for a vane pump, of this kind (German printed and published patent application 3,214,212), the pressure relief valve behaves in such a way that the valve opens at a given hydraulic pressure (control pressure) and hydraulic fluid is delivered to the unpressurised tank. That pressure relief valve whose opening and closing pressure is controlled by a spring force, respectively by an electro-hydraulic valve force, has the disadvantage that although the pressure relief valve opens as soon as the set control pressure of the pump is reached, the pump pressure nevertheless continues to rise for the time being, since only slightly afterwards, that is after the pressure relief valve has opened and hydraulic fluid is running off to the unpressurised tank, a pressure difference can be built up at the orifice.This pressure difference then leads, with a time lag, to a pressure drop in the pressure chamber of the control piston as a consequence of which, again with a time lag, the pump is controlled down or throttled. Now, if the consumer suddenly requires an elevated delivery flow the control sequence of the pump is inverse to that mentioned above, again with a time lag existing until the demanded delivery flow is actually supplied. Such a pressure control apparatus leads to an undesirable extent of hysteresis of the family of pressure characteristics of the pump.
It is,therefore, an object of the invention to create a pressure control apparatus for a hydraulic pump, in particular for a vane pump, which with the aid of simple means and minor constructional efforts results in a low amount of hysteresis at the hydraulic pump.
According to the present invention, there is provided a pressure control apparatus for a hydraulic pump, in particular for a vane pump, with a positioning piston-and-cylinder unit and a control piston-and cylinder unit whose cylinder chambers are linked to a consumer pressure line of the hydraulic pump and whose pistons engage on opposite sides of an adjusting element, in particular a stroke ring of a vane pump, influencing the delivery rate of the pump, the positioning piston having an area smaller than that of the control piston which is spring-loaded in the direction of the maximum delivery rate of the hydraulic pump, and with an orifice configured in a section of the pressure line leading to the said control piston-and-cylinder unit, a pressure relief valve furnished with a port toward an unpressurised tank being connected between the said orifice and the said control piston-and-cylinder unit, characterised in that the pressure at the said pressure relief valve varies depending on the delivery flow in accordance with a desired characteristic curve of the valve device.
At the same time, the properties of the pressure relief valve attained by the characteristic accelerate the pressure decrease, respectively the pressure build up, in the control pressure circuit of the control piston-and-cylinder unit. In this way, a more sensitive control with shorter times of response of the hydraulic pump is obtained.
A particularly good control of the hydraulic pump results when the characteristic curve of the pressure relief valve has a descending slope. This has already been verified by practical tests, and results in a pump distinguished by a low amount of hysteresis.
A pressure relief valve featuring a descending characteristic is obtained in that there exists a flow deflection at the closing element for the generation of forces of flow. While a valve having these features is already described in the Swiss patent No.
390,017, this valve does not serve, within the scope of that patent, to control a hydraulic pump as is, indeed, expressly intended by the present invention. In order to obtain a characteristic curve with a descending slope in a pressure relief valve of this kind, the valve seat and the valve closing member must be given such a shape that the flow is deflected by the shut-off body less than 90 relative to the direction in which the sealing body moves during opening.
In a further advantageous version of the present invention, it is envisaged that the pressure relief valve is a proportional valve in which the range of the valve force decreasing at constant flow from a determined amount of valve travel onwards is utilised for the P-Q characteristic with a descending slope. With this variant of the present invention, a control behaviour of the hydraulic pump as that already described above is achieved.
A further pressure control apparatus allows to be obtained in that the pressure relief valve is a proportional valve which is controlled by an electric signal depending on the consumer pressure. In an arrangement of this type, the hydraulic pressure existing in the pressure line is transduced by a sensor into an electric signal which serves to control the pressure relief valve. In this context, the sensor must be configured such that the electric signal controls the proportional valve in a way so as to give rise to a characteristic curve with a descending slope which, in its turn, leads to the desired control of the hydraulic pump.
In order that the proportional valve receives a signal from the pressure-responsive electric sensor only from a determined control pressure onwards, provision is made according to the present invention to configure a measuring arrangement comparing the consumer pressure with a rated pressure between the sensor and the pressure relief valve, which measuring arrangement furnishes an electric signal to open or close to the pressure relief valve after a given rated pressure has been exceeded or fallen short of. A measuring arrangement of this type, as for example a comparator, compares a given rated pressure with the actual pressure existing in the pressure line.As soon as the actual pressure exceeds the rated pressure, the threshold value of the comparator is also exceeded and impulses are transmitted to the proportional electro-hydraulic valve which result in a descending P-Q characteristic at the valve.
The level of the control pressure is rendered variable by the rated value of the measuring arrangement being adjustable. In this manner, the pressure control apparatus permits being set to different control pressures.
An especially simple pressure-responsive electric sensor, which is proven practically in a variety of applications, is a resistive or piezo-resistive pressure pick-up. Using such an arrangement a particularly good control behaviour of the pressure control apparatus is achieved. In lieu of the pressure pick-ups described above, also a quartz pickup may be utilised.
An embodiment of the present invention will now be described by way of example with reference to the accompanying drawing.
The drawing is a diagrammatic representation of a pressure control apparatus for a controllable vane pump 1 which is shown in non-throttled or controlled-down condition with maximum delivery rate. The vane pump 1 is furnished with a slotted rotor 2 which is supported in a casing (not shown in the drawing) and in which vanes 3 are radially slidably arranged. The external ends of these vanes 3 slide on the inner surface of a cylindrical stroke ring 4 forming cells 5 in conjunction with it.
The stroke ring 4 constitutes the adjusting element of pump 1 and is arranged radially slidably relative to the rotor 2 for this purpose so that the excentricity is variable during operation of pump 1.
For adjustment of the stroke ring 4, a positioning piston 6, forming part of a positioning piston-andcylinder unit 7, engages on one side of the stroke ring 4, and a control piston 8, of a control pistonand-cylinder unit 9, engages on the other side. The control piston 8 is provided with a piston area larger than that of the positioning piston 6 and is loaded by a spring 11 located in the inner space of the cylinder 10 of the control piston-and-cylinder unit 9. Two pressure lines 13 and 14 lead from the consumer pressure line 12 of the vane pump 1 to the piston-and cylinder units 7 and 9. The consumer pressure line 12 leads to one or several consumers, for example to a cylinder or a motor.
A point with a constricted cross section, for example an orifice 15, is arranged in the pressure line 14 going from the pressure line 12 to the control piston and-cylinder unit 9. From the orifice 15 to the control piston-and-cylinder unit 9, there runs a pressure line 24 to which a pressure relief valve 18 is connected. A return line 16 leads from the pressure relief valve 18 to an unpressurised tank 17. The pressure relief valve is configured as a proportional electro-hydraulic pressure valve in this embodiment. In the drawing, the pressure relief valve 18 is shown in closed condition since the pump 1 is set to the maximum delivery rate.
A pressure-responsive sensor 19 transducing the hydraulic pressure into an electric signal and transmitting it via an electric line 20 to a comparator 21 is connected to the consumer pressure line 12.
From the comparator 21, an electric line 22 leads to the electro-hydraulically actuatable proportional pressure valve 18.
The mode of operation of the pressure control apparatus is described in more detail in the following.
Under the action of the spring 11 arranged in the control piston-and-cylinder unit 9, the stroke ring 4 is set to maximum excentricity and, consequently, to the maximum flow rate when the vane pump 1 is not running. This condition is shown in the drawing. The level of the control pressure is adjusted by a rated value (rated pressure) 23 at the comparator 21.
If, for example on account of a low volume flow or no volume flow at all of a consumer, the pressure in the system rises up to short of the control pressure, the signal emitted by the sensor 19 does not yet suffice to transmit an opening signal to the proportional valve because the rated value 23 of the comparator 21 which is set to the control pressure is still higher than the actual value of the sensor 19. Already in the event of a minor excess pressure in the pressure line, the actual value of the sensor 19 will exceed the rated value 23 of the comparator 21 and upon exceeding of this threshold an electric signal will be transmitted to the proportional pressure valve 18. The proportional pressure valve 18 then opens, and a control oil stream will flow off from the consumer pressure line 12 of the pump 1 via the proportional pressure valve 18 to the unpressurised tank 17. The pressure drop brought about at the orifice 15 by the flow of the hydraulic fluid causes a pressure decrease at the orifice 15 and in the pressure line 14 going to the control piston-and-cylinder unit 9, as an effect of which a particularly quick control takes place due to the slide to the right of the control piston 8 and of the positioning piston 6. As a consequence of the slide of the positioning piston 6 and of the control piston 8, the stroke ring 4 is also shifted to the right as viewing the drawing so that pump 1 assumes a position of lower flow rate. In the event of an extreme shift to the right of the stroke ring 4 which comes about, for example, when the consumer is switched off, only the pump leakage is balanced and the flow through the proportional valve 18 conserved in order to maintain the pressure.
When there is a sudden increase of the volume flow at the consumer, the pressure will decrease both in the proportional valve 18 and at the sensor 19, and this will cause the proportional valve 18 quickly to close. The control sequence now proceeds in the inverse order relative to the one already described above.
Claims (11)
1. A pressure control apparatus for a hydraulic pump, in particular for a vane pump, with a positioning piston-and-cylinder unit and a control piston-and cylinder unit whose cylinder chambers are linked to a consumer pressure line of the hydraulic pump and whose pistons engage on opposite sides of an adjusting element, in particular a stroke ring of a vane pump, influencing the delivery rate of the pump, the positioning piston having an area smaller than that of the control piston which is spring-loaded in the direction of the maximum delivery rate of the hydraulic pump, and with an orifice configured in a section of the pressure line leading to the said control piston-and-cylinder unit, a pressure relief valve furnished with a port toward an unpressurised tank being connected between the said orifice and the said control piston-and-cylinder unit, characterised in that the pressure at the said pressure relief valve (18) varies depending on the delivery flow in accordance with a desired characteristic curve of the valve device.
2. A pressure control apparatus as claimed in claim 1, characterised in that the characteristic curve of the said pressure relief valve (18) has a descending slope.
3. A pressure control apparatus as claimed in claim 2, characterised in that means are provided at the valve seat or at the valve closing member of the said pressure relief valve (18) which bring about a flow deflection at the closing element for the generation of forces of flow.
4. A pressure control apparatus as claimed in claim 2, characterised in that the said pressure relief valve (18) is a proportional valve in which the range of the valve force decreasing at constant flow from a determined amount of valve travel onwards is utilised for the P-Q characteristic with a descending slope.
5. A pressure control apparatus as claimed in claim 2, characterised in that the said pressure relief valve (18) is a proportional valve which is controlled by an electric signal (19) depending on the consumer pressure.
6. A pressure control apparatus as claimed in claim 5, characterised in that a measuring arrangement (21) comparing the consumer pressure with a
rated pressure is configured between the said pressure-responsive electric signal (19) and the said pressure relief valve (18), which said measuring arrangement (21) furnishes an electric signal to open or close to the said pressure relief valve (18) after a given rated pressure has been exceeded or fallen short of.
7. A pressure control apparatus as claimed in claim 6, characterised in that the rated value of the said measuring arrangement (21) is adjustable.
8. A pressure control apparatus as claimed in claim 6, characterised in that the said pressure-responsive electric signal (19) is generated by a resistive pressure pick-up.
9. A pressure control apparatus as claimed in claim 6, characterised in that the said pressure-responsive electric signal (19) is generated by a piezo-resistive pressure pick-up.
10. A pressure control apparatus as claimed in claim 6, characterised in that the said pressure-responsive electric signal (19) is a quartz pick-up.
11. A pressure control apparatus for a hydraulic pump substantiaily as herein described with reference to and as illustrated in the accompanying drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19833347015 DE3347015A1 (en) | 1983-12-24 | 1983-12-24 | PRESSURE CONTROL DEVICE FOR A HYDRAULIC PUMP, IN PARTICULAR A LEAF CELL PUMP |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8430974D0 GB8430974D0 (en) | 1985-01-16 |
| GB2151705A true GB2151705A (en) | 1985-07-24 |
| GB2151705B GB2151705B (en) | 1988-02-03 |
Family
ID=6218099
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08430974A Expired GB2151705B (en) | 1983-12-24 | 1984-12-07 | Variable-delivery sliding-vane rotary pump |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS60153480A (en) |
| DE (1) | DE3347015A1 (en) |
| ES (1) | ES283592Y (en) |
| FR (1) | FR2557215A1 (en) |
| GB (1) | GB2151705B (en) |
| IT (1) | IT1181930B (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4655689A (en) * | 1985-09-20 | 1987-04-07 | General Signal Corporation | Electronic control system for a variable displacement pump |
| GB2202006A (en) * | 1987-02-18 | 1988-09-14 | Eaton Corp | Rotary fluid pressure device |
| US4790214A (en) * | 1985-08-02 | 1988-12-13 | Kabushiki Kaisha Toyota Chuo Kenkyusho | Revolution speed ratio control system for a continuously variable transmission |
| FR2764336A1 (en) * | 1997-06-05 | 1998-12-11 | Hydraulique Chateaudun L | Fuel feed control mechanism for aircraft turbines |
| WO2005026553A1 (en) * | 2003-09-12 | 2005-03-24 | Pierburg S.P.A. | Pumping system employing a variable-displacement vane pump |
| US7108493B2 (en) | 2002-03-27 | 2006-09-19 | Argo-Tech Corporation | Variable displacement pump having rotating cam ring |
| WO2007015135A1 (en) * | 2005-08-02 | 2007-02-08 | Pierburg Pump Technology Italy S.P.A. | Two-setting variable-eccentricity vane pump |
| CN100462552C (en) * | 2004-09-22 | 2009-02-18 | 山东交通学院 | Mono-active blade type secondary component |
| WO2012149929A2 (en) * | 2011-05-05 | 2012-11-08 | Ixetic Bad Homburg Gmbh | Variable displacement pump |
| WO2015074700A1 (en) * | 2013-11-21 | 2015-05-28 | Pierburg Pump Technology Gmbh | Variable displacement lubricant pump |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3538643A1 (en) * | 1985-10-30 | 1987-05-14 | Rexroth Mannesmann Gmbh | Device for controlling the pressure of a hydrostatic drive |
| CH671435A5 (en) * | 1986-07-16 | 1989-08-31 | Denise Meneguz | |
| DE3840549A1 (en) * | 1988-12-01 | 1990-06-07 | Rexroth Mannesmann Gmbh | Device for driving a variable delivery (displacement, volume) pump |
| DE4222644C2 (en) * | 1992-07-10 | 1998-10-29 | Wilhelm Hoevecke | Rotary disc machine that can be operated as a motor or pump |
| DE19722495B4 (en) * | 1996-06-07 | 2005-09-29 | Volkswagen Ag | Pump with adjustable delivery volume |
| EP1130262B1 (en) * | 2000-03-02 | 2007-12-19 | Volkswagen Aktiengesellschaft | Gear pump with flow capacity changing sliding unit |
| DE102004002062A1 (en) * | 2004-01-15 | 2005-08-04 | Volkswagen Ag | Gear pump with flow control |
| DE102005016181B4 (en) * | 2005-04-08 | 2018-05-09 | Robert Bosch Automotive Steering Gmbh | Regulating device for a hydraulic conveyor |
| CN105697368B (en) * | 2014-11-27 | 2018-11-30 | 上海汽车集团股份有限公司 | Variable delivery pump and oil pump |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1245197A (en) * | 1959-02-28 | 1960-11-04 | Teves Kg Alfred | Hydraulic shut-off, pressure limiting, flow control or bypass valve |
| DE2141722A1 (en) * | 1971-08-20 | 1973-03-01 | Bosch Gmbh Robert | PRESSURE REGULATOR FOR AN ADJUSTABLE PUMP |
| DE2214013A1 (en) * | 1972-03-23 | 1973-09-27 | Siegfried Leverberg | PRESSURE CONTROL DEVICE |
| FR2195271A1 (en) * | 1972-08-04 | 1974-03-01 | Peugeot & Renault | |
| DE2302047C3 (en) * | 1973-01-17 | 1979-09-20 | Demag Drucklufttechnik Verwaltungsgesellschaft Mbh, 6000 Frankfurt | Control device for adjusting the control element influencing a drive motor of a compressor or a pump |
| US3924970A (en) * | 1973-11-28 | 1975-12-09 | Gen Motors Corp | Electrically controlled fuel pump |
| GB1483396A (en) * | 1975-02-14 | 1977-08-17 | Coal Ind | Methods of and apparatus for controlling hydraulic equipment |
| US4116002A (en) * | 1977-08-22 | 1978-09-26 | Eaton Corporation | Control for a variable displacement pump or motor |
| DE3016609A1 (en) * | 1980-04-30 | 1981-11-05 | G.L. Rexroth Gmbh, 8770 Lohr | Radial vane type pump - has throughput controlled by positioning valve energised by signal from discharge flow meter |
| DE3143074A1 (en) * | 1981-10-30 | 1983-05-11 | Robert Bosch Gmbh, 7000 Stuttgart | Device for controlling the pressure and flow of an adjustable pump |
| DE3200126A1 (en) * | 1982-01-05 | 1983-07-14 | Mannesmann Rexroth GmbH, 8770 Lohr | Control device for a variable displacement pump |
| DE3214212A1 (en) * | 1982-04-17 | 1983-10-20 | Alfred Teves Gmbh, 6000 Frankfurt | Pressure control device for pumps, especially vane cell pumps |
-
1983
- 1983-12-24 DE DE19833347015 patent/DE3347015A1/en not_active Withdrawn
-
1984
- 1984-12-07 GB GB08430974A patent/GB2151705B/en not_active Expired
- 1984-12-18 JP JP59265489A patent/JPS60153480A/en active Pending
- 1984-12-21 IT IT24205/84A patent/IT1181930B/en active
- 1984-12-21 ES ES1984283592U patent/ES283592Y/en not_active Expired
- 1984-12-24 FR FR8419779A patent/FR2557215A1/en active Pending
Cited By (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4790214A (en) * | 1985-08-02 | 1988-12-13 | Kabushiki Kaisha Toyota Chuo Kenkyusho | Revolution speed ratio control system for a continuously variable transmission |
| US4655689A (en) * | 1985-09-20 | 1987-04-07 | General Signal Corporation | Electronic control system for a variable displacement pump |
| GB2202006A (en) * | 1987-02-18 | 1988-09-14 | Eaton Corp | Rotary fluid pressure device |
| FR2764336A1 (en) * | 1997-06-05 | 1998-12-11 | Hydraulique Chateaudun L | Fuel feed control mechanism for aircraft turbines |
| US8740593B2 (en) | 2001-04-05 | 2014-06-03 | Eaton Industrial Corporation | Variable displacement pump having a rotating cam ring |
| US9435338B2 (en) | 2001-04-05 | 2016-09-06 | Eaton Industrial Corporation | Variable displacement pump having rotating cam ring |
| US7491043B2 (en) | 2001-04-05 | 2009-02-17 | Argo-Tech Corporation | Variable displacement pump having a rotating cam ring |
| US7108493B2 (en) | 2002-03-27 | 2006-09-19 | Argo-Tech Corporation | Variable displacement pump having rotating cam ring |
| WO2005026553A1 (en) * | 2003-09-12 | 2005-03-24 | Pierburg S.P.A. | Pumping system employing a variable-displacement vane pump |
| CN100462552C (en) * | 2004-09-22 | 2009-02-18 | 山东交通学院 | Mono-active blade type secondary component |
| US8425210B2 (en) | 2005-08-02 | 2013-04-23 | Pierburg Pump Technology Italy S.P.A. | Two-setting variable-eccentricity vane pump |
| CN101341339B (en) * | 2005-08-02 | 2010-05-26 | 皮尔博泵技术意大利公司 | Double-adjustment variable-eccentricity impeller pump |
| WO2007015135A1 (en) * | 2005-08-02 | 2007-02-08 | Pierburg Pump Technology Italy S.P.A. | Two-setting variable-eccentricity vane pump |
| WO2012149929A2 (en) * | 2011-05-05 | 2012-11-08 | Ixetic Bad Homburg Gmbh | Variable displacement pump |
| WO2012149929A3 (en) * | 2011-05-05 | 2013-09-19 | Ixetic Bad Homburg Gmbh | Variable displacement pump |
| WO2015074700A1 (en) * | 2013-11-21 | 2015-05-28 | Pierburg Pump Technology Gmbh | Variable displacement lubricant pump |
Also Published As
| Publication number | Publication date |
|---|---|
| IT1181930B (en) | 1987-09-30 |
| DE3347015A1 (en) | 1985-07-04 |
| ES283592U (en) | 1985-05-16 |
| FR2557215A1 (en) | 1985-06-28 |
| IT8424205A0 (en) | 1984-12-21 |
| GB2151705B (en) | 1988-02-03 |
| GB8430974D0 (en) | 1985-01-16 |
| ES283592Y (en) | 1986-01-01 |
| JPS60153480A (en) | 1985-08-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |