Controlled cylinder retraction with a closed hydraulic system

Patent metadata

Field	Value
Publication number	US-12084134-B2
Application number	US-201917312520-A
Country	US
Kind code	B2
Filing date	Oct 29, 2019
Priority date	Dec 13, 2018
Publication date	Sep 10, 2024
Grant date	Sep 10, 2024

Abstract

An apparatus having an accumulator fluidly coupled to a cylinder having a moveable rod and a pressure relief valve, the cylinder configured to produce an increase in resistance to retraction of the cylinder by re-routing fluid flow to the accumulator through the pressure relief valve after the rod has reached a defined retraction distance.

First claim

At least the following is claimed:

1. An apparatus, comprising:
an accumulator; and
a cylinder fluidly coupled to the accumulator, the cylinder comprising:
a first portion comprising a first port, a second port, and a pressure relief valve, the pressure relief valve configured to regulate fluid flow from the second port to the accumulator;
a ram in slidable relation to the first portion, the ram comprising an internal recess and a predefined stroke length;
a spring disposed in the internal recess; and
a rod moveable by the spring relative to the first port while permitting fluid flow, wherein the cylinder is configured to increase resistance to retraction of the ram by re-routing fluid flow to the accumulator through the pressure relief valve after the rod has reached a defined retraction distance.

2. The apparatus of claim 1 , wherein the first portion comprises a cylinder head and a rod guide, the cylinder head comprising the first port, the second port, and the pressure relief valve.

3. The apparatus of claim 2 , wherein the rod is disposed between the spring and the cylinder head.

4. The apparatus of claim 1 , wherein the accumulator comprises a port and the first portion comprises plural fluid passageways, the plural fluid passageways comprising a first fluid passageway that fluidly couples the first port to the accumulator and a second fluid passageway that fluidly couples the second port to the first fluid passageway.

5. The apparatus of claim 4 , wherein the pressure relief valve is configured to regulate flow from the second port to the first fluid passageway through the second fluid passageway.

6. The apparatus of claim 4 , wherein the pressure relief valve is configured upon activation to permit fluid flow from the second port to the first fluid passageway when the rod prevents fluid flow from the first port to the accumulator.

7. The apparatus of claim 4 , wherein the pressure relief valve is configured to prevent fluid flow from the second port to the first fluid passageway when the rod permits fluid flow from the first port to the accumulator.

8. An endless track system comprising:
an endless track frame comprising a drive wheel, an idler wheel, and an endless track belt; and
a track tensioning system configured to control tension of the endless track belt, the track tensioning system comprising an apparatus coupled to the idler wheel by a linkage, the apparatus comprising an accumulator and a cylinder comprising a moveable rod and a pressure relief valve, the cylinder fluidly coupled to the accumulator and configured to regulate fluid flow through a first of plural fluid passageways fluidly coupling the cylinder and the accumulator, wherein the apparatus is configured to control tension between the endless track belt and the drive wheel by producing an increase in cylinder pressure by re-routing of the fluid flow to the accumulator through a second of the plural fluid passageways comprising the pressure relief valve after the rod has reached a defined retraction distance.

9. The system of claim 8 , wherein the cylinder comprises:
a first portion comprising a first port, a second port, and the pressure relief valve, the pressure relief valve configured to regulate fluid flow from the second port to the accumulator;
a ram in slidable relation to the first portion according to a predefined stroke length, the ram comprising an internal recess;
a spring disposed in the internal recess;
a rod moveable by the spring and configured to regulate fluid flow to the accumulator from the first port to the accumulator, the movement of the rod relative to the first port causing the re-routing of the fluid flow through the pressure relief valve.

10. The system of claim 9 , wherein the first portion comprises a cylinder head and a rod guide, the cylinder head comprising the first port, the second port, and the pressure relief valve.

11. The system of claim 10 , wherein the rod is disposed between the spring and the cylinder head.

12. The system of claim 9 , wherein the accumulator comprises a port and the first portion comprises the plural fluid passageways, the plural fluid passageways comprising the first of plural fluid passageways that fluidly couples the first port to the port and the second of the plural fluid passageways that fluidly couples the second port to the first of the plural fluid passageways.

13. The system of claim 12 , wherein the pressure relief valve is configured to regulate flow from the second port to the first of the plural fluid passageways through the second of the plural fluid passageways.

14. The system of claim 12 , wherein the pressure relief valve is configured to permit fluid flow from the second port to the first of the plural fluid passageways when the rod prevents fluid flow from the first port to the accumulator.

15. The system of claim 12 , wherein the pressure relief valve is configured to prevent fluid flow from the second port to the first of the plural fluid passageways when the rod permits fluid flow from the first port to the accumulator.

16. A track tensioning method for controlling track tension for an endless track system for a vehicle, the endless track system comprising a drive wheel, an idler wheel, and an endless track belt, the method comprising:
responsive to application of a braking force of the vehicle, adjusting the track tension using an apparatus comprising an accumulator, a cylinder comprising a moveable rod and a pressure relief valve, and a linkage coupling the apparatus and the idler wheel; and
during retraction of the idler wheel and the cylinder, controlling tension between the endless track belt and the drive wheel by producing an increase in cylinder pressure by re-routing fluid flow to the accumulator from a first of plural fluid passageways to a second of the plural fluid passageways comprising the pressure relief valve after the rod has reached a defined retraction distance.

17. The method of claim 16 , further comprising regulating flow from one port of the cylinder to the first of the plural fluid passageways.

18. The method of claim 16 , further comprising permitting fluid flow from one port of the cylinder to the first of the plural fluid passageways when fluid flow through another port of the cylinder is prevented by the rod.

19. The method of claim 16 , further comprising preventing fluid flow from one port of the cylinder to the first of the plural fluid passageways when the fluid flow through another port of the cylinder is not prevented by the rod.

20. The method of claim 16 , wherein the adjustment includes moving a ram of the cylinder through a predefined stroke length.

Assignees

• Agco Corp

Inventors

• Smith Evan Thomas
• Hruska Derek D
• Gustafson Alan D

Classifications

• F15B15/1423

  Component parts; Constructional details · CPC title

• F15B1/04

  Accumulators · CPC title

• B62D55/30

  Track-tensioning means · CPC title

• B62D55/305 Primary

  acting on pivotably mounted idlers · CPC title