DK201570578A1

DK201570578A1 - Double acting hydraulic actuator

Info

Publication number: DK201570578A1
Application number: DKPA201570578A
Authority: DK
Inventors: Jørgen Lambæk
Original assignee: Thor-Lem As
Priority date: 2015-09-07
Filing date: 2015-09-07
Publication date: 2017-03-20
Also published as: DK178959B1

Abstract

The invention relates to a double acting hydraulic actuator unit with manual pumping means, the actuator comprising a valve housing in fluid connection with the manual pumping means, a hydraulic cylinder with a piston having a piston rod extending from the cylinder and a reservoir for hydraulic fluid in connection with the manual pumping means and the valve housing, where the respective cavities of the cylinder on either sides of the piston being in fluid connection with the valve housing, where the valve housing comprises a main direction valve system controlling flow between the pump and the respective sides of the piston, and where a fluid flow channel between the respective sides of the piston towards the fluid reservoir is provided in dependence of the main valve position when no pressure is applied from the manual pumping means.

Description

Double acting hydraulic actuator Field of the Invention

The present invention relates to hydraulic actuators, more specifically to double acting hydraulic actuators with manual pumping devices for creating pressure on one side of a piston in a hydraulic cylinder.

Background of the Invention

Hydraulic actuators are well-known devices for a number of purposes. A single acting hydraulic actuator will, as the name indicates, be able to create pressure in one direction and will need an external force to allow the piston to travel in an opposite direction.

Double acting hydraulic actuators will allow a hydraulically forced movement of a piston in two directions of the cylinder.

The present invention relates to the area of double acting hydraulic actuators of the type with manual pumping devices.

Both the single acting and the double acting hydraulic actuators have advantages and disadvantages, directly connected with their mode of operation as explained above.

If a double acting hydraulic actuator is used in a context where an external load is applied to the actuator piston and the load is relieved the piston will revert to its position prior to the load application and hence potentially create damage or danger to nearby property, goods or individuals.

Object of the Invention

The objective of the present invention is to provide a double acting hydraulic actuator of the type comprising a manual pumping device, which actuator shows an increased flexibility and safety in the operation.

Description of the Invention

According to the invention the objective is achieved through a double acting hydraulic actuator unit with manual pumping means, the actuator comprising a valve housing in fluid connection with the manual pumping means, a hydraulic cylinder with a piston having a piston rod extending from the cylinder and a reservoir for hydraulic fluid in connection with the manual pumping means and the valve housing, where the respective cavities of the cylinder on either sides of the piston being in fluid connection with the valve housing, where the valve housing comprises a main direction valve system controlling flow between the pump and the respective sides of the piston, and where a fluid flow channel between the respective sides of the piston towards the fluid reservoir is provided in dependence of the main valve position when no pressure is applied from the manual pumping means.

By means of such construction it is possible to maintain pressure equilibrium on both sides of the hydraulic piston when applying a force or load to the piston rod and moving this with respect to the longitudinal direction of the cylinder, and hence the risk of any damage or injury following the returning of the piston to original position will be eliminated.

The objective is further achieved through a valve housing for a double acting hydraulic actuator comprising a pressurized fluid inlet, a main direction valve system, fluid flow outlets towards a first side and a second side, respectively, of a piston, where a fluid flow channel between the respective sides of the piston towards the fluid reservoir in dependence of the main valve position in the event where no pressure is applied from the manual pumping means.

Such valve housing may be utilized in a double acting hydraulic actuator according to the invention, either as a separate unit connected to other elements of such hydraulic actuator or as an integrated element in a combined unit.

Finally the objective is achieved through a vehicle comprising a frame and a load carrier mounted pivotably on the frame, where a double acting hydraulic actuator accord ing to any of the preceding claims is mounted in connection with the frame and in connection with the load carrier to allow raising or lowering of the load carrier.

Such vehicles are often using manually operated hydraulic actuator for pivoting a load carrier part. A car trailer or similar is a well-known example. Often only one person is available to operate the actuator and move for example a car, which obviously is a difficult task. By setting the control valve in a position for neutral operation, moving the mass center of the load, e.g. a car, will allow for an attenuated pivoting of the load carrier and allow the user of moving the car without further assistance. The same may happen during loading of the vehicle, just in an opposite direction

Description of the Drawing FIG. 1 is a side view of a double acting hydraulic actuator with a valve housing; FIG. 2 is a detailed exploded view of the hydraulic actuator; FIG. 3 is a detailed exploded view of the valve housing; FIG. 4 is a sectional view of a valve housing; FIG. 5 is a side view and end views of a valve housing: FIG. 6 is a top view of a valve housing; FIG. 7 shows three side views of a valve element; FIG. 8A-8C are sectional views of a valve housing depicting flow directions for pumping mode; FIG. 9A and 9B are sectional views of a valve housing depicting flow directions for manual piston displacement mode modes.

Detailed Description of the Invention FIG. 1 shows an example of an actuator unit according to the invention. The actuator unit comprises valve housing with an integrated manual pumping device, a hydraulic cylinder connected with the valve housing, a piston movable within the cylinder and a piston rod extending from the cylinder. A fluid reservoir is provided as a mantle around the hydraulic cylinder and is connected with the valve housing through fluid conduits.

The pumping device comprises a handle pivotably connected to the pumping piston and to the valve housing. FIG. 2 shows all details of an actuator according to the invention. A sectional view of a hydraulic actuator is shown as well as the piston and piston rod construction together with associated sealing means. The cylinder housing inner surface constitutes the hydraulic cylinder and the piston is sliding in the longitudinal direction of this in dependence of an applied force or load, either directly fluid pressure onto the piston surface or an external load onto the piston rod extending from the cylinder housing. FIG. 3 shows the valve and pumping arrangement with all details in an exploded view. The main valve element 18 is explained in more details in connection with FIG. 7. The valve housing 4 and the flow passages creating the improved function are explained further in connection with FIGS. 4,5,6,8 and 9. FIG. 4 shows a sectional view of the housing 4. The valve housing 4 comprises the pumping device as an integrated part and the pumping cylinder 10 appears from the top view. A fluid conduit is shown at the bottom of the cylinder. Two fluid conduits are shown, which serve the purpose of allowing fluid to flow to and from the fluid reservoir when a pressure is applied on the piston rod and the main control valve is positioned to allow flow from a desired side of the piston to the fluid reservoir. One of the conduits serve the purpose of returning fluid on a first side, when the piston is pulled towards the outer end of the cylinder and the other conduit serves the purpose of returning fluid when the piston is pushed toward the inner end of the cylinder. The cavity 11 is the main control valve housing, where the main control valve 18 is inserted and when turned is capable of leading fluid flow in a desired direction. The capability of leading the flow is obtained from fluid conduits or channel openings 14,15,16,17 in the housing and corresponding openings and channels 20,21 in a valve body 18 inserted in the valve housing FIG. 5 shows an end view as well as side views of the valve housing 4. The area 3 indicates the wall of the fluid reservoir and the area 1 indicates the hydraulic cylinder housing. The opening 15 is a fluid inlet/outlet from the valve housing towards the inner end of the cylinder. The opening 14 is a fluid inlet/outlet from the valve housing 4 towards the outer end of the cylinder. The openings 12 and 13 are outlet openings from the fluid reservoir 3. FIG. 6 shows a top view of the valve housing 4. The pumping cylinder 10 appears and the conduit at the bottom as well. The conduit is connected with a fluid inlet conduit connecting the fluid reservoir with the pumping cylinder. The main control valve cylinder is indicated by 11. FIG. 7 shows the valve body 18 seen from different angles. Three circumferential incisions are provided for accommodating O-ring sealing elements. The valve body has a hollow interior area 22 from which channels extend to the surface of the valve body and partly around the valve body. FIGS. 8A-8C shows the direction of fluid flow in various modes of operation. In FIG. 8A it is shown how the hydraulic fluid is flowing into the pump housing when moving the pump piston upwards and, when pressing the piston downwards again, is flowing into the hydraulic cylinder on the near side of the actuator piston, also designated the plus side of the piston and forcing the piston outwards. The far side of the actuator piston forces hydraulic fluid out of the hydraulic cylinder and into the fluid reservoir. In FIG. 8B it is shown how the hydraulic fluid is flowing into the pump housing when moving the pump piston upwards and, when pressing the piston downwards again, is flowing into the hydraulic cylinder on the far side of the actuator piston, and forcing the piston inwards. The near side of the actuator piston forces hydraulic fluid out of the hydraulic cylinder and into the fluid reservoir. In FIG. 8C it is shown how the hydraulic fluid is flowing into the pump housing when moving the pump piston upwards and flowing into fluid reservoir when pushing the pump piston downwards. The drawings 8A and 8B show normal operational mode of the hydraulic actuator using the pump. FIG. 8C is a neutral mode of the pump.

In FIG. 9A it is shown how the hydraulic fluid is flowing from the fluid reservoir and into the near side of the hydraulic cylinder and how hydraulic fluid is flowing from far side of the hydraulic cylinder and into the fluid reservoir. In FIG. 9B it is shown how the hydraulic fluid is flowing from the fluid reservoir and into the far side of the hydraulic cylinder and how hydraulic fluid is flowing from near side of the hydraulic cylinder and into the fluid reservoir . In the FIGS. 9A and 9B it is possible to apply a force onto the piston via the piston rod and move the piston and piston rod in a longitudinal direction of the cylinder and by the fluid flow described, obtain pressure equilibrium on the two sides, the near side and the far side of the hydraulic cylinder. The equilibrium ensures that the position of the piston is maintained after releasing the applied force and thereby ensures that no damage or harm is done on nearby objects or individuals. To enable this function the main valve must be positioned to allow the flow in the respective directions, i.e. when achieving the flow indicated in FIG. 9A the valve must be positioned corresponding to the position to obtain the pumping flow shown in FIG. 8A, and when achieving the flow indicated in FIG. 9B the valve must be positioned corresponding to the position to obtain the pumping flow shown in FIG. 8B.

Although explained by use of a specific example and a specific configuration of the flow channels it should be appreciated that other configurations of flow channels and arrangement of the elements of the hydraulic actuator unit will be covered by the definition of the invention. For example the various elements of the hydraulic actuator unit may be separate elements connected through hydraulic hoses or tubes.

Claims

1. A double acting hydraulic actuator unit with manual pumping means, the actuator comprising a valve housing in fluid connection with the manual pumping means, a hydraulic cylinder with a piston having a piston rod extending from the cylinder and a reservoir for hydraulic fluid in connection with the manual pumping means and the valve housing, where the respective cavities of the cylinder on either sides of the piston being in fluid connection with the valve housing, where the valve housing comprises a main direction valve system controlling flow between the pump and the respective sides of the piston, and where a fluid flow channel between the respective sides of the piston towards the fluid reservoir is provided in dependence of the main valve position when no pressure is applied from the manual pumping means.

2. A double acting hydraulic actuator according to claim 1, where the actuator comprises a housing comprising pump unit and valve arrangement with fluid reservoir inlet to the pump and a valve opening when pump creates vacuum.

3. A double acting hydraulic actuator according to claim 1 or 2, where a channel is extending from the pump to the near side of the hydraulic cylinder, a channel is extending from the pump to the far side of the hydraulic cylinder, a valve closing the one channel while keeping the other open.

4. A double acting hydraulic actuator according to any of the preceding claims, the housing comprising a channel leading fluid from the near side of the hydraulic cylinder to the fluid reservoir and further a channel leading fluid to the far side of the hydraulic cylinder when applying a load onto the piston in a direction towards the near side of the hydraulic cylinder and the housing comprising a channel leading fluid from the far side of the hydraulic cylinder to the fluid reservoir and further a channel leading fluid to the near side of the hydraulic cylinder when applying a load onto the piston in a direction towards the near side of the hydraulic cylinder.

5. A valve housing for a double acting hydraulic actuator comprising a pressurized fluid inlet, a main direction valve system, fluid flow outlets towards a first side and a second side, respectively, of a piston, where a fluid flow channel between the respective sides of the piston towards the fluid reservoir in dependence of the main valve position in the event where no pressure is applied from the manual pumping means.

6. A valve housing according to claim 5, the housing comprising a channel leading fluid from the near side of the hydraulic cylinder to the fluid reservoir and further a channel leading fluid to the far side of the hydraulic cylinder when applying a load onto the piston in a direction towards the near side of the hydraulic cylinder and the housing comprising a channel leading fluid from the far side of the hydraulic cylinder to the fluid reservoir and further a channel leading fluid to the near side of the hydraulic cylinder when applying a load onto the piston in a direction towards the near side of the hydraulic cylinder.

7. A vehicle comprising a frame and a load carrier mounted pivotably on the frame, where a double acting hydraulic actuator according to any of the preceding claims is mounted in connection with the frame and in connection with the load carrier to allow raising or lowering of the load carrier.