WO2012159153A1

WO2012159153A1 - Force conversion mechanism

Info

Publication number: WO2012159153A1
Application number: PCT/AU2012/000560
Authority: WO
Inventors: Ralph Tony Sarich
Original assignee: Linear Technologies Pty Ltd
Priority date: 2011-05-20
Filing date: 2012-05-18
Publication date: 2012-11-29

Abstract

A force conversion mechanism comprising a transfer member disposed about an anchor point, the transfer member including first and second spaced apart annular bearing surfaces having different diameters, a smaller diameter one of said bearing surfaces being configured to extend loosely around the anchor point so that an input force urging the larger bearing surface toward the anchor point causes the transfer member to rotate, thereby advancing the smaller bearing surface along the anchor point to provide an output force in a direction generally perpendicular to the input force.

Description

FORCE CONVERSION MECHANISM

FIELD OF THE INVENTION The present invention relates to a force conversion mechanism. More particularly, but not exclusively, the invention relates to a mechanism for converting a force in a first direction to one which acts in a second direction which is generally perpendicular to the first direction. BACKGROUND OF THE INVENTION

Machines commonly require an input force acting in one direction to be translated or converted so that it acts in another direction so that it may be utilised. Previous mechanisms for achieving such a conversion can be complicated and ineffective.

Examples of the invention seek to solve, or at least ameliorate, one or more disadvantages of previous force conversion mechanisms.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a force conversion mechanism comprising a transfer member disposed about an anchor point, the transfer member including first and second spaced apart annular bearing surfaces having different diameters, a smaller diameter one of said bearing surfaces being configured to extend loosely around the anchor point so that an input force urging the larger bearing surface toward the anchor point causes the transfer member to rotate, thereby advancing the smaller bearing surface along the anchor point to provide an output force in a direction generally perpendicular to the input force. Preferably, the anchor point is a shaft around which the transfer member is disposed. The shaft can be circular. The shaft can be truncated so that one of the bearing surfaces can pass over the truncated end of the shaft Preferably, the transfer member is integrally formed. Preferably, the transfer member is in the form a conical shaped element.

Preferably, the transfer member is housed within an expandable chamber which surrounds the anchor point.

According to the present invention, there is also provided a force conversion mechanism comprising: a plunger, the plunger including a sliding element at one end and a lateral member at an end opposite to the sliding element; a sleeve; and an insert, wherein the sliding element is slidably received in the sleeve and the lateral member is received in a recess formed in the insert, the insert and the sleeve being configured so that the sleeve can move laterally with respect to the insert thereby causing the lateral member to bear against an edge of the recess and pivot so that an end of the lateral member moves away from the sleeve in response to a lateral input force acting on the sleeve, thereby providing an output force which acts in a direction generally perpendicular to the input force.

Preferably, the lateral member is a planar disc. Preferably, the sliding element is a ball. Preferably, the mechanism further includes a ring for housing the insert and restraining the sleeve. BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further described, by way of non-limiting example only, with reference to the accompanying drawings in which:

Figure 1A is a sectional side view of a mechanism of one embodiment of the invention in a first condition of use;

Figure 1 B is a side view of the mechanism of Figure 1 A; Figure 1C is a plan view of the mechanism of Figure 1 A;

Figure 2A is a sectional side view of the mechanism of Figure 1 in a second condition of use;

Figure 2B is a side view of the mechanism of Figure 2A;

Figure 2C is a plan view of the mechanism of Figure 2A;

Figure 3A is a sectional side view of a mechanism of another embodiment of the invention in a first condition of use;

Figure 3B is a sectional side view of the mechanism of Figure 3 A in a second condition of use;

Figure 4 A is a plan view of the mechanism of Figure 3 A when used in connection with an actuator; and

Figure 4B is a sectional side view of the arrangement of Figure 4A.

DETAILED DESCRIPTION

With reference to Figure 1, there is shown a force conversion mechanism 10. The mechanism 10 comprises a transfer member in the form of a conical element 12 which is disposed about an anchor point, which in the described example is a sleeve 26, The conical element 12 is a hollow truncated cone or frustoconical element. The conical element 12 has first and second spaced apart annular bearing surfaces 13 and 15 respectively which have different diameters. Each of the bearing surfaces are configured so that a force bears against it so that the force may be converted using the transfer member 12. A smaller of said surfaces, which in the described example is the first bearing surface 13, is configured to extend loosely around the sleeve 26 so that an input force urging the larger surface 15 toward the sleeve 26 causes the conical element 12 to rotate or tilt, thereby advancing the smaller bearing surface 12 along the sleeve 26 to provide an output force in a direction generally perpendicular to the input force.

The conical element 12 is disposed within a housing 14 which is in the form of a cylinder with one end generally closed and other open. In a resting state a lower surface 16 of the conical element 12 rests squarely on an internal surface of the closed end of the housing 14.

Disposed adjacent the open end of the housing 14 is a circular cam head 20. The cam head 20 forms an upper part of a plunger 22, a shaft 24 of which is restrained for linear movement within a fixed sleeve 26. Sleeve 26 is fixed to ground plate 17 and the housing 14 is free to move laterally with respect to the sleeve until the conical element has rotated a predetermined amount and locks. An open upper end 18 of the conical element 12 is arranged to fit loosely around the sleeve 26. The open upper end 18 of the conical element 12 is disposed proximal to the open end of the housing 14. The plunger 22 and the housing 14 together define an expandable chamber.

With reference to Figure 2A, it can be seen that the application of a force A, in a direction which is toward the sleeve 26 or generally radially inward with regard to the conical element 12, to an external surface of the housing 14 causes the conical element 12 to rotate or tilt within the housing 14 in a direction which is clockwise with respect to Figure 2A, resulting in the first bearing surface 13 of the conical element 12 being forced upward, thereby converting the direction of input force A perpendicularly to a new direction shown by arrow B. Sleeve 26 is truncated so that as the open upper end 18 of the conical element 12 moves upward, it passes over the end of sleeve 26, allowing it to rotate further. The open upper end 18 may be configured so that, after a predetermined amount of rotation, it locks onto shaft 24 to limit the amount of movement of the cam head 20. Alternatively, the open upper end 18 may be configured so as to allow full rotation of the conical element 12, as shown in Figure 2B.

Depending on the application for which the mechanism 10 is used, internal friction within the mechanism may occur. Friction reducing coatings may be used to address these issues or ball bearings may be incorporated into the housing 14.

Depending on the application for which the mechanism 10 is used, a return spring may be required to ensure that the mechanism returns to a neutral position. If a constant load is applied to the plunger 22, the mechanism may return to its neutral state without the need for a return spring. In one example, a return spring may be fixed to the base 17 and pass around at least a portion of the circumference of the housing 14 so that movement of the housing 14 relative to the base 17 encounters some resistance, thereby causing the mechanism to return to its neutral position. In another example, a leaf spring fixed to the base 17 may act upon the housing 14 to urge it to a neutral position.

In the described example, a conical element 12 is used, though it will be appreciated that this element may be replaced with a rigid part having two rings fixed together with a coupling element. It will also be appreciated that two rigid forks, each of which pass around the shaft, also fixed together with a coupling element, may alternatively be used.

Figure 3 A illustrates another force translation mechanism 1 10. This mechanism 110 comprises a plunger 112 which includes a circular head 114, a stem 116 and a slider, which is shown in the form of a ball 118. The ball 118 is slidably received in sleeve 120. Use of a ball 1 18 for the slider allows the shaft to pivot with respect to a longitudinal axis of the sleeve 120. The mechanism 110 includes a ring 122 and an insert 124. The insert 124 is generally annular and an outermost surface is configured to fit inside the ring 122. The insert 124 may be held fixed to an inside surface of the ring 122 using a fastener such as a grub screw for example. The insert 124 has an inner recess 126 which is configured to receive . head 114. In the example shown, the head 114 is in the form of a planar circular disc, though other shapes are also possible if the recess 126 in the recess 126 of the insert 124 is configured to match the shape of the head.

The ring 122 is fixed to the insert 124 in such a manner so as to maintain a gap 127 in which a flange 128 of the sleeve 120 can be received. The diameter of the flange 128 is larger than aperture 130 of the ring 122 so that the sleeve 120 is coupled to the ring 122 ' and the insert 124, though lateral movement between the ring 122/insert 124 and the sleeve 120 is still possible.

With reference to Figure 3B, it can be seen that lateral movement of the sleeve 120 with respect to ring 122, under the action of force A, causes the head 114 of the plunger 112 to tilt or rotate. Due to this rotation, a tip 132 of the plunger 112 is forced upwards, thereby converting the direction of force A to that of force B. This conversion provides an output force which acts in a direction generally perpendicular to a lateral input force acting on the sleeve 120. This output force is generally parallel to a longitudinal axis of the sleeve 120. Depending on the application for which the mechanism 110 is used, internal friction within the mechanism may occur. Friction reducing coatings may be used to address these issues or ball bearings may be incorporated into the flange 128 to improve sliding movement.

Depending on the application for which the mechanism 110 is used, a return spring may be required to ensure that the mechanism returns to a neutral position. If a constant load is applied to the head 114, the mechanism may return to its neutral state without the need for a return spring. In one example, a return compression spring may be fitted between the ball 118 and the insert 124 to urge the ball to a resting position. Alternatively, a return spring may be fitted between the sleeve 120 and the ring 122 to urge these parts to a neutral position relative to each other.

In the described example, a circular head 114 is used, though it will be appreciated that this may be replaced with an elongate member which is configured to pivot in only two dimensions with respect to the insert 122.

Figures 4A and 4B illustrate an example of the mechanism 110 in use. The mechanism 110 is fixed to an actuator 150 having a platform 152 which is required to be lifted along direction B. Input force A is available though acts in a direction generally perpendicular to that in which it is needed, direction B, and is thus required to be converted so that it can be utilised. Installing mechanism 110 in communication with force A and actuator 150 provides the required force conversion. When the sleeve 120 is acted upon by the force A, the sleeve moves laterally with respect to the ring 122 and the insert 124. By the engagement of the flange 128 within the gap 127, the movement of the sleeve 120 is restrained so as to be only in a lateral direction. The movement of the sleeve 120 causes the head 1 14 of the plunger 112 to rotate, thereby lifting tip 132 and platform 152.

It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims.

Claims

1. A force conversion mechanism comprising a transfer member disposed about an anchor point, the transfer member including first and second spaced apart annular bearing surfaces having different diameters, a smaller diameter one of said bearing surfaces being configured to extend loosely around the anchor point so that an input force urging the larger bearing surface toward the anchor point causes the transfer member to rotate, thereby advancing the smaller bearing surface along the anchor point to provide an output force in a direction generally perpendicular to the input force.

2. A mechanism according to claim 1 , wherein the anchor point is a shaft around which the transfer member is disposed.

3. A mechanism according to claim 2, wherein the shaft is circular.

4. A mechanism according to claim 2 or claim 3, wherein the shaft is truncated so that one of the bearing surfaces can pass over the truncated end of the shaft

5. A mechanism according to any one of the preceding claims, wherein the transfer member is integrally formed.

6. A mechanism according to any one of the preceding claims, wherein the transfer member is in the form a conical shaped element.

7. A mechanism according to any one of the preceding claims, wherein the transfer member is housed within an expandable chamber which surrounds the anchor point.

8. A force conversion mechanism comprising:

a plunger, the plunger including a sliding element at one end and a lateral member at an end opposite to the sliding element;

a sleeve; and

an insert,

wherein the sliding element is slidably received in the sleeve and the lateral member is received in a recess formed in the insert, the insert and the sleeve being configured so that the sleeve can move laterally with respect to the insert thereby causing the lateral member to bear against an edge of the recess and pivot so that an end of the lateral member moves away from the sleeve in response to a lateral input force acting on the sleeve, thereby providing an output force which acts in a direction generally perpendicular to the input force.

9. A mechanism according to claim 8, wherein the lateral member is a planar disc.

10. A mechanism according to claim 8 or claim 9, wherein the sliding element is a ball.

1 1. A mechanism according to any one of claims 8 to 10, further including a ring for housing the insert and restraining the sleeve.