GB2152196A - Fluid control valve unit - Google Patents
Fluid control valve unit Download PDFInfo
- Publication number
- GB2152196A GB2152196A GB08432226A GB8432226A GB2152196A GB 2152196 A GB2152196 A GB 2152196A GB 08432226 A GB08432226 A GB 08432226A GB 8432226 A GB8432226 A GB 8432226A GB 2152196 A GB2152196 A GB 2152196A
- Authority
- GB
- United Kingdom
- Prior art keywords
- control plate
- cover plates
- pieces
- valve unit
- distance
- 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
- 239000012530 fluid Substances 0.000 title claims description 10
- 239000004568 cement Substances 0.000 claims description 15
- 238000003475 lamination Methods 0.000 claims description 13
- 239000000853 adhesive Substances 0.000 claims description 8
- 230000001070 adhesive effect Effects 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 238000000576 coating method Methods 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 5
- 229910010293 ceramic material Inorganic materials 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 2
- 239000002659 electrodeposit Substances 0.000 claims 1
- 238000005507 spraying Methods 0.000 claims 1
- 238000010276 construction Methods 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 2
- 238000003698 laser cutting Methods 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K3/00—Gate valves or sliding valves, i.e. cut-off apparatus with closing members having a sliding movement along the seat for opening and closing
- F16K3/02—Gate valves or sliding valves, i.e. cut-off apparatus with closing members having a sliding movement along the seat for opening and closing with flat sealing faces; Packings therefor
-
- 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
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K11/00—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves
- F16K11/02—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit
- F16K11/06—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements
-
- 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
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K11/00—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves
- F16K11/02—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit
- F16K11/06—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements
- F16K11/065—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements with linearly sliding closure members
- F16K11/0655—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements with linearly sliding closure members with flat slides
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Sliding Valves (AREA)
- Valve Housings (AREA)
- Multiple-Way Valves (AREA)
Description
SPECIFICATION
A fluid control valve unit
The subject matter of this invention is a fluid control valve unit comprising at least two stationary external cover plates between which are located one or several distance pieces for creating a receptacle chamber for a movable control plate, movement of which controls at least one fluid passageway.
In such a valve unit, the fluid passageway may be formed by one or several ports in the control plate and/or in one or both cover plates, which can be either completely or partially closed off or completely connected to overlap with each other by means of the control plate.
Valves of this kind are preferentially employed in oil and water hydraulic systems. The function of these valves can also be carried out by valves of the piston design in which the control piston is located in a bore allowing for a small clearance. As the control plates or pistons move with a clearance between themselves and the stationary valve components, whereby the danger of leakage caused by this clearnace must be kept as small as possible, the quality of valves of this kind depends on compliance with the requirement for the narrowest of gaps, and consequently on the closest of manufacturing tolerances, while at the same time ensuring that the ease of motion of the moving control components remains unimpaired.
Compliance with these extremely close manufacturing tolerances has, however, meant relatively high manufacturing costs up to now.
In the case of the known multi-directional control valves of wafer or plate construction, the gap between the control plate and one of the cover plates is created by distance pieces which are thicker than the control plate so that the cover plate thickness is less than the clear distance between the cover plates by the requisite gap dimension. Compliance with these thickness dimensions in the micron range is, as can be easily appreciated, reiatively expensive.
The invention is based on the technical problem of removing this disadvantage and creating a control valve unit, suitable for example for a straightway or multi-directional control valve, of the type mentioned in the introduction, which is easy to manufacture, simple in design and reliable in operation.
According to a first aspect of the present invention there is provided a control valve unit comprising at least two stationary external cover plates between which one or several distance pieces are located in order to create a receptacle chamber for a movable control plate, movement of which controls at least one fluid passageway, in which the distance piece or pieces and the control plate are plane-parallel and are of the same thickness as each other, and between the distance piece or pieces and at least one of the cover plates there is located a lamination so that the thickness of the control plate is less than the clear distance between the cover plates whereby there is formed a defined gap between the control plate and one of the cover plates.
Thus, the distance pieces and the control plate are plane-parallel and each of the same thickness as the other(s), and between the distance pieces and the cover plates there is located a lamination for forming a defined gap between the control plate and the cover plates.
According to one construction of the invention, the lamination consists of an adhesive or a cement, the components thus cemented together, and the control plate, forming a constructional element, ready for example for testing and/or assembly in a valve housing.
Advantageously, the adhesive or cement incorporates particles of a defined size which correspond to the requisite size of the gap between the control plate and one of the cover plates.
According to a further development of the invention, the cover plates, the distance piece(s) and the control plate are all manufactured from a ceramic material.
Preferably, the distance piece(s) and the control plate are formed from one single piece processed such that it is plane-parallel and thus of uniform thickness, the distance pieces and the control plate being subsequently separated from one another.
According to a second aspect of the present invention, there is provided a method of manufacturing a valve unit comprising at least two stationary external cover plates between which one or several distance pieces are located in order to create a receptacle chamber for a movable control plate movement of which controls at least one fluid passageway, wherein a work-piece of material from which the distance piece(s) and the control plate can be formed is processed for plane-parallelity between its faces and of uniform thickness, the distance piece or pieces and the control plate are then separated from the work-piece and/or from one another, and those parts are assembled with the cover plates with a lamination between the distance piece or pieces and at least one of the cover plates.
The lamination which forms the gap can be produced in various ways. Coatings on the distance pieces and/or the cover plates are conceivable. In the case of a coating on the cover plates, one or more masks will be required in the operating region of the control plate so that no coating is applied in those areas.
In the alternative case of coating means for the distance pieces, correlation between the control plate and the distance pieces which come from a common processed piece must be ensured because the distance pieces or control plates from other workpieces may differ considerably in dimension, something which, incidentally, is quite permissible. A combination of distance pieces and control plates which were not subjected to this common process must, therefore, be avoided for the reasons mentioned.
A cement layer in accordance with the one feature of the invention, which cements the distance pieces and the cover plates together, has proved particularly advantageous. The cement lamination, once set, absorbs the forces resulting from the subsequent pressure loading on the cover plates. The resistance to pressure of these cement laminations is quite considerable as they are kept within the range of 0.5-2 microns, producing a total gap at the control plate of appox. 1-4 microns depending upon the defined size of the particles added to the cement. The components thus cemented together can, if the cover plates are metallic and where they also constitute the valve body, be bolted together after the cement has set.During the setting process, only moderate force may be applied for displacing the excess cement, otherwise there is the danger of the particles being crushed.
In cases where the cover plates do not also constitute the valve body, the cemented and proper constructional unit can be easily inserted into a housing.
The layer forming the gap could, of course, also be manufactured by some other method.
Coatings on the distance pieces or on the cover plates are also conceivable in the form of chemical or electro-plating deposits, and also deposits formed in the so-called PVD and
CVD processes.
A valve unit in accordance with the invention, of wafer or plate construction can, in contrast to piston valves, be simply manufactured owing to the flat, undercut-free shape of the plates and distance pieces, employing sintered materials which can be processed by pressing, firing and subsequent flat working.
Of particular interest in this connection is the applicability of aluminium oxide ceramics or other ceramics. These materials undergo little or no wear owing to their considerable hardness, and can be manufactured cheaply with flat surfaces of very low peak-to-valley values.
The surface quality depends upon the required gap tolerance. Where tolerances are close, the peak-to-valley height can be easily maintained below Ra = 0.1 ,um.
In the event that the distance pieces and the control plate are, in accordance with a preferred feature of the invention, manufactured from a single piece which has been processed for plane-parallelity with uniform thickness throughout, the subsequent separation of the components from one another can be carried out by means of saws or laser cutting. No distortion of the components will take place owing to the sintered structure which is completely stress-free.
A valve unit in accordance with the invention is, of course, suitable for other applications apart from the hydraulics sector. For example, applications in pneumatic systems, and particularly high-pressure pneumatic systems is quite conceivable. Likewise, a valve unit of this kind can also be employed as a mixer valve unit for sanitary valves and other sanitary fitting applications.
The invention may be put into practice in many ways but one specific embodiment will now be described by way of example with reference to the drawings which illustrate an embodiment of a control unit for a multidirectional high-pressure gate valve. In the drawings:
Figure 1 shows a longitudinal section of the valve unit;
Figures 2 and 2A show an enlarged illustration of a constructional unit consisting of cover plates, distance pieces and the control plate, with Figure 2A showing a larger-scale detail of the region marked X;
Figure 3 shows a section taken on the line
B-B of Figure 2; and
Figure 4 shows a section in accordance with the line A-A of Fig. 2.
The stationary external cover plates are designated in the Figures by reference 3, and the distance pieces by reference 4. As can be seen, the cover plates 3 and the distance pieces 4 together form a receptacle chamber for a moving control plate 5. As is particularly shown in the detail enlargement in Figure 2A, a lamination 6 is located between the distance pieces 4 and the cover plates 3 in order to form a defined gap 7 between the control plate 5 and the cover plates 3.
The distance pieces 4 and the control plate 5 were formed integrally together in a common workpiece processed for plane-parallelity between its faces, so that each is of exactly the same thickness.
The lamination 6 comprises a cement with particles 8 of a defined size, this size corresponding to the gap 7 (1.5-2 m). The components 3 and 4 thus cemented together form, with the control plate, a proper construction unit ready for testing and assembly.
As is further demonstrated, the cover plates 3 and the distance pieces 4 are additionally connected together by means of centering pins 9.
The distance pieces 4 and the control plate 5 were manufactured from one single planeparallel piece of sintered ceramic material of uniform thickness. Between the distance pieces and the control plate, separating grooves were preformed on the single-piece sintered material, and the subsequent cutting process could be carried out without great expense by means of saws or laser cutting.
The mode of operation of the embodiment shown in Figure 1 is as follows:- The valve unit shown by way of example is for a threeway brake fluid valve, whereby the third connection is located at the flange face 10 on the right hand side. With the control plate 5 in its mid-position, both the high-pressure side P and the return from the valve chamber to the tank are shut off. If the control plate 5 is moved to the right, the pressure medium flows into the chamber and passes from there to the consumer. If, on the other hand, the control plate is moved to the left, the oil received by the consumer can be fed back into the tank.
The cover plates 3 may be made of metal and may be designed to form or constitute part of the valve body. The unit may be held together by bolts or reliance may be had on the adhesive fixing. Adhesive or cement may be used between the distance pieces and one of the cover plates or at each end of the distance pieces to secure both cover plates. It would be conceivable to use adhesive or cement without particles, for some applications.
In other embodiments, a single distance piece suitably shaped, may be used.
Claims (11)
1. A control valve unit comprising at least two stationary external cover plates between which one or several distance pieces are located in order to create a receptacle chamber for a movable control plate, movement of which controls at least one fluid passageway, in which the distance piece or pieces and the control plate are plane-parallel and are of the same thickness as each other, and between the distance piece or pieces and at least one of the cover plates there is located a lamination so that the thickness of the control plate is less than the clear distance between the cover plates whereby there is formed a defined gap between the control plate and one of the cover plates.
2. A valve unit in accordance with claim 1, in which the lamination consists of an adhesive or a cement, the components thus cemented together forming, together with the movable control plate, a constructional unit.
3. A valve unit as claimed in claim 2, in which the cement or adhesive incorporates particles of a defined size which corresponds to the required size of the gap between the control plate and one of the cover plates.
4. A valve in accordance with any one of claims 1 to 3, in which the cover plates, the distance piece or pieces, and the control plate are manufactured from a ceramic material.
5. A valve unit in accordance with any one of the preceding claims, in which the distance piece or pieces and the control plate are formed from a comnon work-piece processed for plane-parallelity and of uniform thickness throughout.
6. A valve unit as claimed in any one of the preceding claims, adapted to form the control unit of a straightway or a multi-directional valve.
7. A method of manufacturing a valve unit comprising at least two stationary external cover plates between which one or several distance pieces are located in order to create a receptacle chamber for a movable control plate movement of which controls at least one fluid passageway, wherein a work-piece of material from which the distance pieces and the control plate can be formed is processed for plane-parallelity between its faces and of uniform thicknesses, the distance piece or pieces and the control plate are then separated from the work-piece and/or from one another, and those parts are assembled with the cover plates with a lamination between the distance piece or pieces and at least one of the cover plates.
8. A method as claimed in claim 7, in which the lamination is formed by adhesive or cement applied to the distance piece or pieces or to one or both cover plates, or it is formed by spraying, electro-deposit, chemical or other coating process.
9. A valve unit substantially as specifically described herein with reference to the drawings.
1 0. A method of manufacturing a valve unit substantially as specifically described herein with reference to the drawings.
11. A valve having a valve unit as claimed in any one of claims 1 to 6 or 9 or as made by a method of claims 7, 8 or 10.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3347135A DE3347135C2 (en) | 1983-12-27 | 1983-12-27 | Straight or multi-way valve in plate design |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8432226D0 GB8432226D0 (en) | 1985-01-30 |
| GB2152196A true GB2152196A (en) | 1985-07-31 |
| GB2152196B GB2152196B (en) | 1986-10-15 |
Family
ID=6218190
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08432226A Expired GB2152196B (en) | 1983-12-27 | 1984-12-20 | Fluid control valve unit |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0147562B1 (en) |
| JP (1) | JPS60139978A (en) |
| KR (1) | KR850005080A (en) |
| AU (1) | AU3262284A (en) |
| BR (1) | BR8405185A (en) |
| CA (1) | CA1254107A (en) |
| DE (2) | DE3347135C2 (en) |
| GB (1) | GB2152196B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8931516B2 (en) | 2007-07-27 | 2015-01-13 | Knorr-Bremse Systeme Fuer Nutzfahrzeuge Gmbh | Pilot-controlled valve having a ceramic control piston |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3620818A1 (en) * | 1986-06-21 | 1987-12-23 | Asys Gmbh Ges Fuer Die Herstel | SOLENOID VALVE FOR LIQUID AND GASEOUS MEDIA |
| DE3731754A1 (en) * | 1987-09-22 | 1989-04-20 | B & S Metalpraecis Gmbh | THREE-WAY FITTING |
| DE3890961T1 (en) * | 1987-11-10 | 1989-12-21 | Masco Corp | A PAIR OF SEALING BODIES MADE OF HARD MATERIAL WITH A LOW FRICTION COEFFICIENT |
| IT1211509B (en) * | 1987-11-10 | 1989-11-03 | Gevipi Ag | PAIR OF SEALING BODIES IN HARD MATERIAL WITH LOW FRICTION COEFFICIENT |
| DE3926846A1 (en) * | 1989-08-15 | 1991-02-21 | Hauhinco Maschf | Piston slide valve for water hydraulics - makes use of ceramic for piston and housing bush |
| DE102005042040B3 (en) | 2005-09-02 | 2007-05-16 | Fresenius Medical Care De Gmbh | gear pump |
| DE102012108711A1 (en) * | 2012-09-17 | 2014-03-20 | Samson Ag | Fluid technical flat slide valve |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB923730A (en) * | 1959-07-31 | 1963-04-18 | Marvin Henry Grove | Improvements in gate valves for fluids |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2893684A (en) * | 1957-06-11 | 1959-07-07 | John L Williams | Corrosion resistant gate valve |
| GB911436A (en) * | 1958-11-27 | 1962-11-28 | Wilmot Breeden Ltd | Fluid control slide valves |
| DE1211452B (en) * | 1964-01-15 | 1966-02-24 | Erich Herion | Control or multi-way spool driven by a piston |
| FR1554564A (en) * | 1965-11-24 | 1969-01-24 | ||
| DE2130773A1 (en) * | 1970-07-02 | 1972-04-13 | Iskra Zd Za Avtomatizacijo V Z | Adhesive for gluing with a precisely determined distance |
| DE2633443A1 (en) * | 1976-07-24 | 1978-01-26 | Festo Maschf Stoll G | SLIDE VALVE |
| JPS53149476A (en) * | 1977-05-31 | 1978-12-26 | Tokyo Shibaura Electric Co | Method of and device for extracting coffee or like |
| DE3150844A1 (en) * | 1981-12-22 | 1983-06-30 | Max Planck Gesellschaft zur Förderung der Wissenschaften e.V., 3400 Göttingen | Process and adhesive for bonding components |
-
1983
- 1983-12-27 DE DE3347135A patent/DE3347135C2/en not_active Expired
-
1984
- 1984-08-31 AU AU32622/84A patent/AU3262284A/en not_active Abandoned
- 1984-09-13 KR KR1019840005575A patent/KR850005080A/en not_active Ceased
- 1984-09-26 CA CA000464033A patent/CA1254107A/en not_active Expired
- 1984-10-03 JP JP59206456A patent/JPS60139978A/en active Pending
- 1984-10-15 BR BR8405185A patent/BR8405185A/en not_active IP Right Cessation
- 1984-10-25 DE DE8484112872T patent/DE3480108D1/en not_active Expired
- 1984-10-25 EP EP84112872A patent/EP0147562B1/en not_active Expired
- 1984-12-20 GB GB08432226A patent/GB2152196B/en not_active Expired
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB923730A (en) * | 1959-07-31 | 1963-04-18 | Marvin Henry Grove | Improvements in gate valves for fluids |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8931516B2 (en) | 2007-07-27 | 2015-01-13 | Knorr-Bremse Systeme Fuer Nutzfahrzeuge Gmbh | Pilot-controlled valve having a ceramic control piston |
Also Published As
| Publication number | Publication date |
|---|---|
| KR850005080A (en) | 1985-08-21 |
| EP0147562A2 (en) | 1985-07-10 |
| EP0147562A3 (en) | 1987-05-27 |
| BR8405185A (en) | 1985-08-13 |
| AU3262284A (en) | 1985-07-04 |
| GB2152196B (en) | 1986-10-15 |
| JPS60139978A (en) | 1985-07-24 |
| CA1254107A (en) | 1989-05-16 |
| DE3347135A1 (en) | 1985-07-11 |
| DE3347135C2 (en) | 1986-04-03 |
| EP0147562B1 (en) | 1989-10-11 |
| GB8432226D0 (en) | 1985-01-30 |
| DE3480108D1 (en) | 1989-11-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| FI82538C (en) | Shutter member of hard material with low coefficient of friction | |
| DE3213378C2 (en) | Multi-layer sliding body and process for its manufacture | |
| GB2152196A (en) | Fluid control valve unit | |
| EP2985497B1 (en) | Closuring element for a vacuum valve with pressed, vulcanised seal | |
| CN102213247B (en) | Be used in the cover of fluid pressure device and the fixation method of this cover | |
| CN108603521B (en) | Synchronous cylinder for continuous pressing equipment | |
| EP4172491B1 (en) | Axial piston machine having a seal ring which is spherical in sections | |
| US3584833A (en) | Sheet metal two-part valve housing | |
| US4277544A (en) | Powder metallurgical articles and method of bonding the articles to ferrous base materials | |
| EP3600731A1 (en) | Composite part | |
| DE20116898U1 (en) | microvalve | |
| EP0946780A1 (en) | Vacuum treatment equipment | |
| DE4414243B4 (en) | ball valve | |
| US5024075A (en) | Method of deforming two opposite edges of a single workpiece by machining, and apparatus for implementing the method | |
| US4983355A (en) | Seal element of hard material sintered from a semi-finished form with organic binder | |
| DE102018127573A1 (en) | Solenoid valve device for a pressure balanced solenoid valve, a pressure balanced solenoid valve, solenoid valve system and method with the solenoid valve device | |
| US4968004A (en) | Shutoff and control valve | |
| EP0803037A1 (en) | Metal valve housing | |
| US6005214A (en) | Method of making wear resistant material lined housings | |
| EP4367418B1 (en) | Compression ring with abutting ends and method | |
| US6254982B1 (en) | Graphite bursting disc | |
| DE3926846A1 (en) | Piston slide valve for water hydraulics - makes use of ceramic for piston and housing bush | |
| DE19725195A1 (en) | Cellular flywheel pump | |
| DE19954456A1 (en) | Water feed valve has housing formed as thin-walled pipe-form component made of stainless steel or copper alloy, and with inlet connector with connection thread formed by non-cutting process | |
| US7401588B1 (en) | Cylinder block with unlined piston bores |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |