Portable self-locking lift system

Patent metadata

Field	Value
Publication number	US-10173872-B2
Application number	US-201514856681-A
Country	US
Kind code	B2
Filing date	Sep 17, 2015
Priority date	Sep 17, 2014
Publication date	Jan 8, 2019
Grant date	Jan 8, 2019

Abstract

A lift system includes a cylinder having an end surface, a threaded member supported for movement with a piston, and a nut threadedly engaging the threaded member and selectively engageable with the end surface. Engagement of the nut and the end surface limits axial movement of the piston relative to the cylinder in at least one direction. A drive mechanism rotates the nut relative to the threaded member, and a control valve controls movement of the piston relative to the cylinder. A drive control mechanism controls operation of the drive mechanism and rotation of the nut. A nut sensor senses a portion of the nut. The nut sensor is in communication with at least one of the control valve and the drive control mechanism. When the nut sensor detects a portion of the nut, the control valve stops movement of the piston or the drive control mechanism stops rotation of the nut.

First claim

What is claimed is:

1. A lift system comprising:
a cylinder having an end surface;
a piston movably supported in the cylinder;
a threaded member supported for movement with the piston;
a nut threadedly engaging the threaded member, the nut being selectively engageable with the end surface, engagement of the nut and the end surface limiting axial movement of the piston relative to the cylinder in at least one direction, the nut defining an outer perimeter and including an external annular groove extending substantially around the outer perimeter;
a drive mechanism including a flexible member operable to rotate the nut relative to the threaded member;
a tension device operable to maintain a predetermined tension in the flexible member;
a control valve operable to control movement of the piston relative to the cylinder;
a drive control mechanism operable to control operation of the drive mechanism and rotation of the nut; and
a nut sensor operable to sense a portion of the nut, the nut sensor being in communication with at least one of the control valve and the drive control mechanism, wherein, when the nut sensor detects the portion of the nut, the control valve stops movement of the piston or the drive control mechanism stops rotation of the nut.

2. The lift system of claim 1 , further comprising a piston sensor operable to sense an end portion of the piston, the piston sensor being in communication with the control valve to stop extension of the piston when the piston sensor detects the end portion of the piston.

3. The lift system of claim 1 , wherein the nut sensor transmits a signal to the drive control mechanism, and wherein, when the nut sensor detects the portion of the nut, the signal is interrupted and the drive control mechanism stops rotation of the nut.

4. The lift system of claim 1 , wherein, when the nut engages the end surface of the cylinder, the nut sensor is aligned with the external annular groove and the control valve permits extension of the piston relative to the cylinder.

5. The lift system of claim 1 , wherein the portion of the nut is positioned between the external annular groove and the end surface of the cylinder, wherein when the portion of the nut is positioned adjacent the nut sensor, the drive control mechanism stops rotation of the nut.

6. The lift system of claim 5 , wherein the nut sensor is a first nut sensor, and wherein the lift system further comprises a second nut sensor operable to sense the nut, wherein, when the annular groove is aligned with the second nut sensor, the nut drive controller stops rotation of the nut when the piston is being retracted.

7. The lift system of claim 6 , wherein the portion of the nut is a first portion, the nut further including a second portion, the external annular groove being positioned between the first portion of the nut and the second portion of the nut, and wherein the second nut sensor is aligned with the second portion of the nut when the nut engages the end surface of the cylinder.

8. The lift system of claim 6 , wherein the first nut sensor is positioned between the end surface of the cylinder and the second nut sensor.

9. The lift system of claim 1 , wherein, during extension and retraction of the piston relative to the cylinder, the nut is driven along the threaded member to alternately abut and be spaced from the end surface of the cylinder.

10. The lift system of claim 1 , wherein the control valve is configured to control at least one of a direction and a speed of fluid flow into the cylinder to control movement of the piston relative to the cylinder.

11. The lift system of claim 1 , wherein the flexible member is a continuous chain, the chain engaging sprocket teeth coupled to the nut.

12. The lift system of claim 1 , wherein the tension device includes at least one roller and a biasing member, the roller engaging a portion of the flexible member, the biasing member biasing the roller into engagement with the flexible member.

13. The lift system of claim 1 , wherein the flexible member extends in an endless loop around the nut and a drive member, wherein the drive member rotates about a drive axis, wherein a line extends between the axis of the threaded member and the drive axis, wherein the tension device includes a first tension device engaging a first portion of the flexible member on a first side of the line, and a second tension mechanism engaging a second portion of the flexible member on a second side of the line.

14. A lift system comprising:
a cylinder having an end surface and extending along a cylinder axis;
a piston supported for movement relative to the cylinder along the cylinder axis;
a threaded member supported for movement with the piston;
a nut threadedly engaging the threaded member, at least a portion of the nut being selectively engageable with the end surface, engagement of the nut and the end surface limiting movement of the piston relative to the cylinder along the cylinder axis in at least one direction; and
a sensor assembly operable to sense a position of the nut relative to the end surface, the sensor assembly being supported for movement relative to the cylinder in a direction transverse to the cylinder axis.

15. The lift system of claim 14 , further comprising a shoe supported for movement relative to the cylinder in the direction transverse to the cylinder axis, and wherein the sensor assembly is coupled to the shoe.

16. The lift system of claim 15 , wherein the sensor assembly includes a first sensor and a second sensor, the second sensor being positioned between the end surface and the first sensor.

17. The lift system of claim 15 , wherein the shoe is engageable with the nut.

18. The lift system of claim 15 , further comprising a biasing member biasing the shoe towards the nut.

19. The lift system of claim 18 , wherein, when the threaded member pivots such that the nut moves away from the sensor assembly, the biasing member biases the sensor assembly toward the cylinder axis.

20. The lift system of claim 19 , wherein, when the threaded member pivots such that the nut moves towards the sensor assembly, the sensor assembly moves away from the cylinder axis.

Assignees

• Actuant Corp

Inventors

• Decker Arnold

Classifications

• B66F3/30 Primary

  with positive brakes or locks · CPC title

• B66F3/24

  fluid-pressure operated (water-pressure machines F03B; hydraulic gearings F16H; cylinders, pistons F16J; fluid-pressure servomotors F15B) · CPC title

• B66F3/08

  screw operated (B66F3/44 takes precedence; gearings F16H) · CPC title