Hybrid clamp force control for lift truck attachment

Patent metadata

Field	Value
Publication number	US-11220417-B2
Application number	US-201916420000-A
Country	US
Kind code	B2
Filing date	May 22, 2019
Priority date	May 22, 2019
Publication date	Jan 11, 2022
Grant date	Jan 11, 2022

Abstract

A hydraulic control circuit operable to selectively hydraulically link first and second hydraulic actuators and to bypass that hydraulic link.

First claim

The invention claimed is:

1. A hydraulic control circuit comprising:
an input port configured to receive pressurized fluid from a pump and return unpressurized fluid to a reservoir
a first output port connectable to a first hydraulic actuator and a second output port connectable to second hydraulic actuator, each of the first output port and the second output port configured to receive pressurized fluid from the input port and also configured to simultaneously deliver said pressurized fluid to its respectively connected hydraulic actuator and receive fluid discharged therefrom;
a selector capable of selectively using fluid discharged from the first hydraulic actuator to pressurize fluid delivered into the second hydraulic actuator; wherein
the first output port and the second output port are each configured to deliver said pressurized fluid from the input port to its respectively connected hydraulic actuator regardless of whether the selector is in the first position or the second position.

2. The hydraulic control circuit of claim 1 where the selector selectively uses fluid discharged from the first hydraulic actuator to pressurize fluid delivered into the second hydraulic actuator automatically based upon the magnitude of fluid pressure provided to the hydraulic control circuit.

3. The hydraulic control circuit of claim 1 where the selector selectively uses fluid discharged from the first hydraulic actuator to pressurize fluid delivered into the second hydraulic actuator automatically based upon which connection of an input port receives pressurized fluid.

4. The hydraulic control circuit of claim 1 selectively connectable to a lift truck attachment having opposed clamps, where the selector is configured to selectively use fluid discharged from the first hydraulic actuator to pressurize fluid delivered into the second hydraulic actuator automatically when the clamps engage a load.

5. The hydraulic control circuit of claim 1 where the selector selectively uses fluid discharged from the first hydraulic actuator to pressurize fluid delivered into the second hydraulic actuator automatically during an opening movement of the hydraulic actuators.

6. The hydraulic control circuit of claim 1 where the selector selectively uses fluid discharged from the first hydraulic actuator to pressurize fluid delivered into the second hydraulic actuator automatically during a portion of a closing movement of the hydraulic actuators and during an opening movement of the hydraulic actuators.

7. The hydraulic control circuit of claim 1 where the selector alternates the control circuit between a first mode where the hydraulic actuators are linked in series and a second mode where the hydraulic actuators are not linked in series.

8. The hydraulic control circuit of claim 7 where in the second mode, the hydraulic actuators are driven in parallel.

9. The hydraulic control circuit of claim 8 including a second selector that controls the flow from a flow divider.

10. The hydraulic control circuit of claim 7 where in the second mode, one hydraulic actuator is moved by the control circuit while the other hydraulic actuator is prevented from moving by the control circuit.

11. A hydraulic control circuit configured to receive pressurized fluid from a pump and return unpressurized fluid to a reservoir, the hydraulic control circuit comprising a selector alternately operable between a first state and a second state during each of which the control circuit pressurizes a first hydraulic actuator and a second hydraulic actuator using pressurized fluid from the pump, wherein in the first state the first hydraulic actuator and the second hydraulic actuator are hydraulically linked and in the second state the first hydraulic actuator and the second hydraulic actuator are not hydraulically linked.

12. The hydraulic control circuit of claim 11 where the selector automatically alternates between the first state and the second state based upon the magnitude of fluid pressure provided to the hydraulic control circuit.

13. The hydraulic control circuit of claim 11 where the selector automatically alternates between the first state and the second state based upon which connection of an input port receives pressurized fluid.

14. The hydraulic control circuit of claim 11 including a resynchronizing valve operable to resynchronize the first hydraulic cylinder with the second hydraulic cylinder.

15. The hydraulic control circuit of claim 11 included in a lift truck attachment having the first hydraulic actuator and the second hydraulic actuator.

16. The hydraulic control circuit of claim 15 where at least one of the first hydraulic actuator and the second hydraulic actuator operates as a valve that selectively permits fluid to pass between a rod side and a head side of the respective hydraulic actuator.

17. The hydraulic control circuit of claim 16 where the valve is a resynchronizing valve configured to resynchronize the first hydraulic actuator with the second hydraulic actuator.

18. The hydraulic control circuit of claim 16 where the valve permits fluid to pass between a rod side and a head side of the respective hydraulic actuator at an end-of-stroke of a closing movement.

19. The hydraulic control circuit of claim 18 where the valve permits fluid to pass between a rod side and a head side of the respective hydraulic actuator at an end-of-stroke of a closing movement.

20. The hydraulic control circuit of claim 16 where the valve permits fluid to pass between a rod side and a head side of the respective hydraulic actuator at an end-of-stroke of a closing movement.

Assignees

• Cascade Corp

Inventors

• Walthers Christopher M

Classifications

• B23Q1/28

  Means for securing sliding members in any desired position · CPC title

• B66F9/184

  Roll clamps · CPC title

• B25B5/16

  Details, e.g. jaws, jaw attachments · CPC title

• B66F9/22 Primary

  Hydraulic devices or systems · CPC title

• B66F9/183

  Coplanar side clamps · CPC title