AU668717B2 - Motion conversion assembly - Google Patents

Description

P P/00/011 Regulation 3.2 6~8 4 1,7

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant: Actual Inventor: Address for Service: FIREBELT PTY LIMITED Idwall Charles Richards TREVOR DREDGE ASSOCIATES Patent Trade Mark Attorneys 13th Floor, 379 Queen Street BRISBANE, QLD, 4000 (GPO Box 1339, BRISBANE, 4001) "Motion Conversion Assembly" Invention Title: Details of Associated Provisional Application No: Australian Patent Application No. PL2254 filed 5 May, 1992.

The following statement is a full description of this invention, including the best method of performing it known to me: a. I It- 2 THIS INVENTION relates to a motion conversion assembly for converting linear motion of a push-pull means to rotation of a shaft or the like and in particular, but not limited to conversion of linear push-pull motion to oscillation.

It is known to employ a pair of double acting hydraulic cylinder assemblies which are coupled to a drive shaft so that the shaft oscillates. In this arrangement, the linear motion of the double acting hydraulic cylinder assemblies is converted to rotation of the shaft. One application of this arrangement is in collection and compaction of garbage in a compaction assembly. In the known compaction assemblies, a blade is mounted on the shaft and sweeps back and forth within a hopper as the hydraulic cylinder assemblies extend and retract in predetermined timed relationship.

While the present compaction assemblies operate satisfactorily, they do not operate to an optimum due to deficiencies in current control arrangements for operating the cylinder assemblies.

15 It is an object of the present invention to alleviate at least to some degree the aforementioned problems of the prior art.

*In one aspect therefore, the present invention resides in a motion conversion assembly comprising a rotatable shaft, a fluid actuated linearly moveable push-pull means being coupled to the shaft so that as the push-pull means moves, the shaft rotates, a drive fluid circuit for supplying drive fluid to the fluid actuated push-pull means to bring about linear motion thereof, the circuit having a rotary valve S: assembly coupled to the shaft and being operable in response to rotation of the shaft to control operation of said push-pull means.

The push-pull means can be any linear motion device including rack and 25 pinion assemblies or fluid driven cylinder assemblies or any other functional equivalent thereof. Preferably, the push-pull means comprises a pair of fluid driven cylinder assemblies having respective cylinders, moveable pistons within the cylinders and respective retractable cylinder rods coupled to the pistons and protruding from the cylinders, the cylinder assemblies being coupled to the shaft so that as the cylinder rods extend or retract, the shaft rotates, the rotary valve being operable in response to rotation of the shaft to selectively divert drive fluid to the respective cylinders. Typically, double acting cylinder assemblies are employed.

3 The rotary valve assembly typically includes a fixed valve member and one or more rotary valve members which typically rotate(s) in predetermined relationship with the shaft. The rotary valve member(s) and shaft typically rotate in concert.

Where the push-pull means comprises a pair of cylinder assemblies, a pair of rotary valve members are employed, a first valve member of said pair controlling fluid to a first one of said cylinder assemblies and a second rotary valve member controlling fluid to a second one of said cylinder assemblies. One form of rotary motion envisaged by the present invention is oscillation of the shaft and to this end, the rotary valve includes a shaft reversal valve member which periodically brings about reverse rotation of the shaft.

The rotary valve typically includes a fixed reference member and as the shaft is typically journalled in bearings. It is preferable therefore that the relationship between the fixed reference member and the shaft be such that at all times the rotary valve maintain a predetermined physical position relative to the shaft independent of variations in shaft position. To this end, the fixed reference member, which is typically an outer casing of the rotary valve, is flexibly or semi-rigidly mounted to i a rigid support. In this way, account can be taken of bearing wear or other circumstances which bring about slight movement of the shaft or the rigid support in order to maintain the predetermined relationship for consistent operation of the rotary valve.

The cylinder assemblies are preferably pivotly mounted to opposite ends of a fixed cross-beam member which can withstand torsion arising from action of the compaction assembly. Typically, the cross-beam comprises a channel with pivotal ends of the respective cylinder assemblies being coupled to opposite ends of the 25 channel.

The blade of the compaction assembly is typically of hollow construction having three spaced plates interconnected by upper and lower webs to form a twotiered structure. The blade is preferably connected to the shaft by wrap around Ushaped plate means which are co-extensive with the upper and lower web sections.

It will be appreciated from the foregoing that the present invention involves a rotary valve which responds to the angular position of the shaft to alter the operation of the push-pull means and thereby motion of the shaft. The push-pull 4 means is preferably indirectly coupled to the shaft via a crank. In the case of a pair of cylinder assemblies, a pair of opposed cranks are preferably employed. The opposed cranks can be formed as a single crank plate coupled to the shaft. Other mechanically equivalent means coupling the cylinder assemblies to the shaft can be employed.

One typical application of the present invention is to a compaction assembly where a blade is coupled to a shaft so that the blade is made to oscillate back and forth within a hopper to compact garbage at each end of the blade's travel. In this arrangement, the blade motion is reversed at the end of respective compaction strokes. The initial reversal is herein termed a return stroke. Thus, motion of the blade involves completion of a compaction stroke followed by a return stroke, a changeover stage and a compaction stroke and on completion of the compaction stroke, the process is reversed in the opposite direction and so forth. Where double acting cylinder assemblies are employed, it is desirable that both cylinder assemblies are extending during completion of the compaction stroke.

Thus, in one typical operation sequence, the rotary valve supplies fluid to the cylinder assemblies to complete a compaction stroke, fluid is delivered to both cylinder assemblies so they extend, after the compaction stroke the return stroke is then initiated and both cylinder assemblies retract until just prior to the changeover 20 stage which occurs between the return stroke to the next compaction stroke. At the changeover stage, the rotary valve causes the first cylinder assembly to float, that is, the first cylinder assembly neither pushes nor pulls but has both sides of its piston at equal pressure thus enabling the second cylinder assembly to continue pulling during its retraction, the rotary valve then operates so that the second cylinder assembly floats while controlling the first cylinder assembly to push by extending, then the rotary valve operates the second cylinder assembly so it also begins to push and the changeover stage is completed. The next compaction stroke is thus initiated and underway. After completion of the next compaction stroke, the rotary valve operates in the opposite sense where both cylinder assemblies retract and another return stroke is commenced and the change over is repeated in the reverse direction with the second cylinder assembly floating initially and so forth.

In a preferred operation, the cylinder assemblies share a common fluid source and the rotary valve functions so that one of the cylinder assemblies floats during a major portion of the return stroke while a higher proportion of fluid is diverted to the other cylinder assembly which can then operate at higher speed during that portion of the return stroke. Thus, in this embodiment, more compaction strokes can be achieved during any given time period.

The rotary valve gives instantaneous response to shaft position and thereby minimises delays which could increase the duration of the changeover stage so that there is a rapid transition from the return stroke to the compaction stroke and therefore the duration of the compaction stroke can be maximised and therefore, the overall force applied during the compaction stroke can be increased.

In order that the present invention can be more readily understood and be put into practical effect, reference will now be made to the accompanying drawings which illustrate one application of the present invention to a compaction assembly and wherein:- Figures 1 and 2 are respective cut-away plan and elevation views illustrating I one embodiment of the present invention; Figure 3 is a schematic fluid control circuit suitable for the compaction assembly of Figures 1 and 2; Figures 4 to 7 are plan views illustrating operation of the compaction 1 20 assembly of Figures 1 and 2 using a fluid control circuit operating as described with reference to Figure 3; and Figures 8 and 9 are respective elevation and plan views of a preferred blade S suitable for the compaction assembly of Figures 1 to 7.

Referring to the drawings and initially to Figure 1, there is illustrated a 25 motion conversion assembly in the form of a compaction assembly 10 including a rotatable shaft 11 journalled in bearings 12 and 13 and driven by push-pull means in the form of a pair of double acting hydraulic cylinder assemblies 14 and 15 so that as the hydraulic cylinder assemblies extend and retract, the shaft 11 rotates to sweep a paddle 16 through a hopper 17. The hydraulic cylinder assemblies are controlled using a rotary valve 17 which shares a common axis with shaft 11 and includes a central shaft 18 which rotates in concert with the shaft 11. In the illustrated embodiment, the rotary valve assembly is operable in response to rotation 6 of the shaft to control operation of the double acting hydraulic cylinder assemblies 14 and As can be seen in Figure 1, the cylinder assemblies 14 and 15 are pivotly coupled to a channel beam 19 which extends across the hopper 17. The cylinder assemblies 14 and 15 are mounted beneath the beam 19 by brackets 20 and 21. The rotary valve 17 is shown in section and includes an outer casing 22 which is fixed relative to the rotation of shaft 18 and is coupled to a mounting tray 22 which is caintilevered from a Y-bracket 23. The tray 22 has a bearing 22a so that the shafts 11I and 18 can rotate relative to the tray 22. The tray 22 is therefore elastically and pivotally mounted to float so that motion of the shaft 11I caused say, by wear in bearings 12 and 13 is taken into account by elastic response and movement of the tray 22 thereby maintaining the proper operational relationship between the moveable parts of the valve 17 and the fixed casing 21. As can be seen, the valve 17 includes in this embodiment four rotary valve members shown at 23, 24, 25 and 26 and in emergency reversal valve shown at 27 which is operable manually using handle 28. Thus, in the case of an emergency, an operator can hit the handle 28 to reverse motion of the blade 16.

The cylinder assemblies 14 and 15 include cylinders 29 and 30 respectively and protruding cylinder rods 31 and 32 which are coupled to a crank 33 which is mounted to the shaft 11. The rotary valve is secured in place on the tray 22 using a atie rod 34.

Referring to Figure 3, there is illustrated the hydraulic circuit by which the blade 16 is driven in its oscillating motion within the hopper 17. As can be seen, the shaft 18 rotates directly in response to rotation of the shaft 11. The moveable 25 part or parts of the rotary valve 17 which in this case includes four respective valve members represented at 23, 24, 25 and 26 with the valve member 23 controlling delivery of fluid to double acting hydraulic cylinder assembly 14, the valve member 24 controlling delivery of fluid to the hydraulic cylinder assembly 15, the rotary valve member 25 controlling reversal of the blade 16 at the end of a compaction stroke and the valve member 26 controlling delivery of fluid to the respective valve members 23 and 24 along pilot lines 35 and 36 and 37 and 38 respectively. The rotary valve member 26 is operable to alternately cause floating of one of the 7 cylinder assemblies 14 or 15 during alternate return strokes and to increase the fluid delivered to the other hydraulic cylinder assembly so that during that portion of the return stroke, the blade travels at higher than normal speed. The valve member 26 also responds to the blade reaching the completion of a compaction stroke to cause a high pressure squeezing action at the end of a compaction stroke by adjusting the bleed rate of fluid from the rams 14 and 15 so that the compaction force is increased just adjacent the end of a compaction stroke.

Referring to Figures 4 to 7, operation of the compaction assembly of Figures 1 to 3 will be described. As can be seen in Figure 4, the rams 14 and 15 are fully extended and are beginning to retract so that the blade 16 is shown at the commencement of its return stroke. During the return stroke, one of the cylinders 14 or 15 is free floating while a greater than normal amount of hydraulic fluid is delivered to the other hydraulic cylinder assembly so that during the return stroke, the blade 16 moves at higher speed until it reaches a position just prior to the position illustrated in Figure 6. The position illustrated in Figure 6 is part way through the changeover whereat the cylinder assemblies 14 and 15 alternate from floating to pushing. The cylinder assembly 14 initially floats while the cylinder I assembly 15 continues to retract after which the cylinder assembly 15 floats while the cylinder assembly 14 begins to extend, the cylinder assembly 15 then begins to 20 extend so that the blade 16 moves into the compaction stroke where it finishes at the position illustrated in Figure 7. This is the opposite position illustrated in Figure 4.

The process then repeats itself and further cycles are repeated in the same way.

As will be seen from Figure 3, the valve members 23 and 24 come into play at the changeover stage between the return stroke and the compaction stroke, the 25 valve member 26 operates to free float the cylinders in alternating fashion via the valve members 23 and 24 while just prior to the end of each compaction stroke, the valve 26 brings about a higher pressure final compaction phase of motion over the last several degrees of movement of the blade during its compaction stroke.

Referring to Figures 8 and 9, the blade 16 is illustrated in more detail and as can be seen, the blade employs three plates 39, 40 and 41 with plate 40 being an intermediate plate, each of the plates 39, 40 and 41 being of the same shape as illustrated in plan in Figure 9. Respective webs 42 and 43 are welded in place between the plates to maintain them in spaced relationship and U-shaped web sections 44 and 45 extend around the shaft and include apertures 46 which take into account the folding of the U-shaped web sections 44 and 45. The U-shaped web sections are welded together with the web sections 42 and 43 at 47 and 48. A pair of strengthening plates 49 and 50 are also welded in place, the neck 51 dividing the body portion 52 from the head section 53. It will be appreciated that the web sections 42 and 43 are each made from a single sheet of material extending around the head portion of the body section 52 and around the head portion 53 and back to the welds 47 and 48.

Whilst the above has been given by way of illustrative example of the present invention, many variations and modifications thereto will be apparent to those skilled in the art without departing from the broad ambit and scope of the invention as set forth in the appended claims.

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Claims (7)

1. A motion conversion assembly comprising a rotatable shaft, a fluid actuated linearly moveable push-pull means being coupled to the shaft so that as the push-pull means moves, the shaft rotates, a drive fluid circuit for supplying drive fluid to the fluid actuated push-pull means to bring about linear motion thereof, the circuit having a rotary valve assembly coupled directly to the shaft and being operable in response to rotation of the shaft to control operation of said push-pull means.

2. The motion conversion assembly according to claim 1 wherein the push-pull means comprises a pair of fluid driven cylinder assemblies having respective cylinders, moveable pistons within the cylinders and respective retractable cylinder rods coupled to the pistons and protruding from the cylinders, the cylinder assemblies being coupled to the shaft so that as the cylinder rods extend or retract, the shaft rotates, the rotary valve assembly being operable in response to rotation of the shaft to selectively divert drive fluid to the respective cylinders.

3. The motion conversion assembly according to claim 1 or claim 2 wherein the j rotary valve assembly includes a fixed valve member and one or more rotary valve members which rotate(s) in predetermined relationship or in concert with the shaft.

4. The motion conversion assembly according to any one of the preceding claims wherein the push-pull means comprises a pair of cylinder assemblies and the rotatary 4 valve assembly employing a pair of rotary valve members, a first valve member of said pair controlling fluid to a first one of said cylinder assemblies and a second rotary valve member: controlling fluid to a second one of said cylinder assemblies. The motion conversion assembly according to any one of the preceding claims wherein the form of rotary motion is oscillation of the shaft and to this end, the rotary S.valve assembly includes a shaft reversal valve member which periodically brings about reverse rotation of the shaft. The motion conversion assembly according to any one of the preceding claims wherein the rotary valve assembly includes a fixed reference member, the relationship between the fixed reference member and the shaft being such that at all times the rotary valve maintains a predetermined physical position relative to the shaft independent of variations in shaft position.

7. The motion conversion assembly according to claim 6 wherein the fixed V .0 reference member is flexibly or semi-rigidly mounted to a rigid support to allow for slight movement of the shaft or the rigid support in order to maintain the predetermined relationship for consistent operation of the rotary valve assembly.

8. The motion conversion assembly according to any one of the preceding claims wherein the cylinder assemblies are pivotly mounted to opposite ends of a fixed cross- beam member which can withstand torsion aris3ing from action of the compaction assembly.

9. A compaction assembly including a motion conversion assembly according to any one of the preceding claims where a blade is coupled to the shaft so that the blade is made to oscillate back and forth within a hopper to compact garbage at each end of the blade's travel, the blade motion being reversed at the end of respective compaction. strokes, the initial reversal being herein termed a return stroke, motion of the blade involving completion of a compaction stroke followed by a return stroke, a changeover stage and a comnction stroke and on completion of the compaction stroke, the process is reversed in the opposite direction, the rotary valve assembly S" minimising delays in the changeovc: stage so that there is a rapid transition from the return stroke to the compaction stroke and therefore the duration of the compaction stroke is maximised and therefore, the overall duration of the compaction stroke is S maximised. 'i 10. A compaction assembly substantially as described with reference to the accompanying drawings. DATED this 2nd day of February, 1996 FIREBELT PTY LIMITED By its Patent Attorneys INTELLPRO i 1 ABSTRACT A motion conversion assembly in the form of a compaction assembly including a rotatable shaft 11 journalled in bearings 12 and 13 and driven by push- pull means in the form of a pair of double acting hydraulic cylinder assemblies 14 and 15 so that as the hydraulic cylinder assemblies extend and retract, the shaft 11 rotates to sweep a paddle 16 through a hopper 17. The hydraulic cylinder assemblies are controlled using a rotary valve 17 which shares a common axis with shaft 11 and includes a central shaft 18 which rotates in concert with the shaft 11. I: tfhe illustrated embodiment, the rotary valve assembly is operable in response to rotation of the shaft to control operation of the double acting hydraulic cylinder assemblies 14 and I ii I r j sebisae otolduig oayvle17wihsae cmo xswt j shaf 11adicue eta hf 8wih oae ncne•wt h hf 1 L.deilutae ebdmnth otr aveasmlyi pral nrepnet i_ i