AU2018204599A1 - A novel mechanism to convert single-direction or oscillating rotational motion into reciprocating motion. - Google Patents

Abstract

WAVE THRUST BEARING USED FOR THE CONVERSION OF ROTARY TO RECIPROCAL MOTION The following mechanism is a novel design of a thrust bearing that transfers motion from a rotary to reciprocal form. The raceway of the bearing rings (1, 3) is projected over three dimensions and conforms to a Sine wave to enable up and down movements while the bearing rings rotate relative to each other. A rebound device (4) maintains contact between the bearing rings and rolling elements. Drawings 1- Fixed bearing ring 2- Rolling element cage 3- Floating bearing ring 4- Rebound device 5- Reciprocating mechanical linkage 4 6- Rotary mechanical linkage 7- Bore 8- Peak 9- Trough (E9 - 7 8 Figure 1 Figure 2 7

Description

WAVE THRUST BEARING USED FOR THE CONVERSION OF ROTARY TO

RECIPROCAL MOTION

DESCRIPTION [001] The present invention relates to a novel mechanism for transferring motion from a rotary input to a reciprocating output without the need for a crankshaft.

[002] Current mechanisms that convert rotary to reciprocating motion typically rely on the use of a crankshaft and flywheel, rotating cam or swashplate device. It is a common aim of engineers to reduce physical volume and mass of these devices to improve the properties of pumps, power tools, linear actuators and other products where these mechanisms are applied.

[003] For a crankshaft or rotating cam to produce work, the orientation of the source of rotation must be orthogonal to the desired direction of reciprocating motion. The changes in orientation required by these designs to achieve the desired form of output leads them to occupy a relatively large volume for a given stroke length.

[004] A swashplate is capable of transferring energy from a rotating driveshaft oriented parallel to the linear output of motion. While compact, the main disadvantage of the swashplate is the requirement for multiple reciprocating elements, to maximise displacement in pumps, for example, and make effective use of the rotation.

[005] The Wave Thrust Bearing addresses these limitations by forming a rolling element raceway of a thrust bearing that conforms to a Sine waveform wrapped around an axis. The invention is comprised of four main components; a fixed bearing ring (1) that is constrained to the mechanism’s case, a rolling element cage (2) that is attached to the fixed bearing ring (1) and contains rolling elements such as ball bearings, a floating bearing ring (3) and a rebound device (4).

[006] Rotational motion becomes linear as the wave of the floating bearing ring (3) moves along the path of the fixed bearing ring (1). Bottom Dead Centre positioning, when the unit is in a contracted state (Figure 3) occurs when the peaks (8) of one bearing ring coincide with the troughs (9) of the other bearing ring. Top Dead Centre positioning, when the unit is in an expanded state (Figure 4) occurs when the peaks of both bearing rings align.

2018204599 25 Jun 2018 [007] The reciprocating element and rotating driveshaft are both connected via mechanical linkages (5, 6 respectively) to the floating bearing ring (3) with access through the bore (7) of the fixed bearing ring (1). The bore (7) can be slotted to prevent rotation of the reciprocating mechanical linkage (5) being transferred to the attached reciprocating element. Otherwise, the reciprocating element will simultaneously rotate and move laterally. The dual motions can be advantageous for certain applications in power tools such as rotary hammers. The rotary mechanical linkage (6) prevents linear forces generated within the Wave Thrust Bearing from being applied to the source of rotation while allowing the floating bearing ring (3) to rotate and reciprocate freely.

[008] A rebound device such as a spring (4) is located on the outside surface of the floating bearing ring (3) to maintain contact between the floating bearing ring (3) and the rolling elements. The rebound device (4) ensures that after reaching Top Dead Centre the floating bearing ring (3) proceeds towards Bottom Dead Centre of the adjacent trough (9) in either a clockwise or counter-clockwise direction and allows the cycle to continue.

[009] The reciprocating output stroke length is equal to the amplitude of the wave and the ratio of strokes per revolution is determined by the number of peaks (8) and troughs (9) in the raceway. This feature can be utilised to extract energy from an oscillating axle such as in wave energy converters where complete rotations in a single direction do not occur.

[010] The materials used in the bearing can be based on existing practice with low friction, hard and temperature stable chrome steels, stainless steel, ceramics and various polymers presenting desirable properties. The type of rolling element used can vary based on application with ball bearings, cylindrical or tapered rollers as existing options.

[011] Figure 1 is an exploded view of all components within the Wave Thrust Bearing. An alternative configuration is possible where the fixed bearing ring (1) is located closer to the source of rotation than the floating bearing ring (3). The rebound mechanism (4) and rotating mechanical linkage (6) in that configuration can be housed between bearing rings to further reduce form factor.

2018204599 25 Jun 2018 [012] Figure 2 is a sectional view of a fixed bearing ring (1) with a distinct difference in height between the peak (8) and trough (9) of the wave-shaped raceway depicted.

[013] Figures 3 and 4 depict the bearing rings positioned at Bottom Dead Centre and Top Dead Centre respectively. The rolling element cage (2) has been omitted for the drawing and only the fixed (1) and floating bearing rings (3) are visible. Dimensions presented are examples to demonstrate stroke length.

[014] The main advantages of the Wave Thrust Bearing are the physical compactness of the mechanism as the reciprocating element and rotary driveshaft are situated along the same axis and the ability to derive complete strokes of the reciprocating element from partial rotations of the driveshaft.

2018204599 25 Jun 2018

Editorial Note

There is one page of claims only

2018204599 25 Jun 2018

WAVE THRUST BEARING USED FOR THE CONVERSION OF ROTARY TO

RECIPROCAL MOTION

Claims (11)

1. THE CLAIMS OF THE INVENTION ARE AS FOLLOWS

   1. A thrust bearing with the raceways of the bearing rings shaped like a sine wave wrapped around an axis allows for the transformation of an input of rotational motion to an output of linear motion as the alignment of the peaks and troughs of the bearing rings changes.
2. 2. One of the bearing rings from the thrust bearing in Claim 1 is fixed to the mechanism’s case.
3. 3. One of the bearing rings from the thrust bearing in Claim 1 is not constrained to the mechanism’s case.
4. 4. The amplitude and wavelength of the bearing rings in Claim 2 and Claim 3 are identical.
5. 5. A rebound device maintains contact between the bearing ring of Claim 3 and the rolling element cage.
6. 6. The rolling element cage that contains low friction balls or rollers is constrained to the bearing ring of Claim 2.
7. 7. A mechanical linkage between the bearing ring of Claim 3 and the rotary input restricts linear forces from being applied to the source of the rotation.
8. 8. A mechanical linkage can be included between the bearing ring of Claim 3 and the reciprocating output to prevent the output from experiencing rotational forces.
9. 9. The bearing ring of Claim 2 has a bore that enables access for the mechanical linkages in Claim 7 and Claim 8 to be attached to the bearing ring of Claim 3.
10. 10. The input of Claim 1 can be in the form of a single-direction or oscillating rotation.
11. 11 .The ratio of reciprocating strokes per rotation of the thrust bearing in Claim 1 is equal to the sum of the number of wave peaks and troughs of the bearing ring in Claim 2.