WO2009047279A2 - Rack and pinion rotary drive - Google Patents

Rack and pinion rotary drive Download PDF

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Publication number
WO2009047279A2
WO2009047279A2 PCT/EP2008/063497 EP2008063497W WO2009047279A2 WO 2009047279 A2 WO2009047279 A2 WO 2009047279A2 EP 2008063497 W EP2008063497 W EP 2008063497W WO 2009047279 A2 WO2009047279 A2 WO 2009047279A2
Authority
WO
WIPO (PCT)
Prior art keywords
rack
pinion
engaging member
rotary drive
teeth
Prior art date
Application number
PCT/EP2008/063497
Other languages
French (fr)
Other versions
WO2009047279A3 (en
Inventor
Andrew Forbes-Buthlay
Original Assignee
Andrew Forbes-Buthlay
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Andrew Forbes-Buthlay filed Critical Andrew Forbes-Buthlay
Publication of WO2009047279A2 publication Critical patent/WO2009047279A2/en
Publication of WO2009047279A3 publication Critical patent/WO2009047279A3/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H19/00—Gearings comprising essentially only toothed gears or friction members and not capable of conveying indefinitely-continuing rotary motion
    • F16H19/02—Gearings comprising essentially only toothed gears or friction members and not capable of conveying indefinitely-continuing rotary motion for interconverting rotary or oscillating motion and reciprocating motion
    • F16H19/04—Gearings comprising essentially only toothed gears or friction members and not capable of conveying indefinitely-continuing rotary motion for interconverting rotary or oscillating motion and reciprocating motion comprising a rack

Definitions

  • the present invention relates to a rack and pinion rotary drive.
  • Rotary motion is obtained by applying fluid or air under pressure to a piston(s) located inside a cylinder. Movement of the piston drives a linear gear rack, which in turn drives a pinion gear mated to it, imparting rotary motion to the output shaft.
  • the output shaft is located and supported between two bearings and is connected either directly to the load, or via a coupling or by linkage.
  • rack and pinion rotary actuators are known. These rotary actuators are available in various sizes and torque outputs and may be powered by either air or hydraulic fluid under pressure.
  • One limiting factor which rack and pinion rotary actuators have in common is a limited degree of rotation. This degree of rotation is determined by rack length and pinion diameter. Typical standard degrees of rotation offered are 90, 180, 360 and 720 degrees.
  • a rack and pinion rotary drive comprising: a) at least two racks adapted to reciprocate linearly between first and second position, b) a pinion having at least one rack engaging member over an arcuate part of the periphery of the pinion and at least one non- rack engaging member over the other arcuate part of the periphery of the pinion, in use the racks being aligned around the pinion such that each rack sequentially is adjacent with and engages a rack engaging member to rotate the pinion as the rack moves from the first to the second position, and disengages from the rack engaging member as the pinion rotates and is adjacent a non-rack engaging member as the rack moves from the second to the first position.
  • the or each rack engaging member may be teeth on the periphery of the pinion which engage with teeth on a rack, the non-rack engaging member may be a toothless periphery of the pinion.
  • another rack engages with the rack engaging member so providing continuous rotational drive to the pinion.
  • each rack may be driven from the first to the second position and vice versa hydraulically, pneumatically, mechanically or electrically, or combinations thereof.
  • a pinion 1 having a rack engaging member in the form of an array of teeth 2 over a first semi-circular arc of the pinion, and a non-rack engaging member in the form of a toothless periphery 3 over the remaining semicircular arc of the pinion.
  • a first rack 10 with teeth 1OA is driven linearly by an actuator 11 from a first withdrawn position (see Figure ID) to a second expanded position (see Figure 1C), and back to a first withdrawn position (see Figure ID).
  • a second rack 20 with teeth 2OA is driven linearly by an actuator 21 from a first withdrawn position (see Figure IB) to a second expanded position (see Figure IA), and back to a first withdrawn position (see Figure IB).
  • rack 10 is in the first position with its teeth 1OA adjacent and just coming into engagement with the teeth 2 on pinion 1.
  • rack 21 is in the second position with its teeth 2OA just disengaging from teeth 2 on pinion 1.
  • actuator 11 starts to expand rack 10 towards its second position with its teeth 1OA adjacent and engaging teeth 2 on pinion 1, so rotating pinion 1.
  • Meantime actuator 21 withdraws rack 20 to its first position with its teeth 2OA adjacent toothless periphery 3 of pinion 1, so its does not rotate pinion 1.
  • rack 20 is in the first position with its teeth 2OA adjacent and just coming into engagement with the teeth 2 on pinion 1.
  • rack 10 is in the second position with its teeth 1OA just disengaging from teeth 2 on pinion 1.
  • actuator 21 starts to expand rack 20 towards its second position with its teeth 2OA adjacent and engaging teeth 2 on pinion 1, so rotating pinion 1.
  • Meantime actuator 11 withdraws rack 10 to its first position with its teeth 1OA adjacent toothless periphery 3 of pinion 1, so its does not rotate pinion 1.
  • rack 10 is back again in the first position with its teeth 1OA adjacent and just coming into engagement with the teeth 2 on pinion 1.
  • rack 21 is back again in the second position with its teeth 2OA just disengaging from teeth 2 on pinion 1.
  • Racks 10,20 may be driven by actuators from the first to the second position and vice versa hydraulically or pneumatically. Alternatively racks 10,20 may be driven mechanically or electrically. Combinations of hydraulic, pneumatic, mechanical and electrical movement are also possible.
  • the invention may take a form different to that specifically described above.
  • more than two racks may be used to drive the pinion.
  • four rack could drive a rack engaging member over a quarter of the periphery of the pinion.
  • the pinion may have more than one rack engaging member and have more than one rack non-engaging member.
  • Such multiple rack engaging members may be axially spaced over the pinion.
  • the rack and pinion may engage by means other than teeth, e.g. engaging friction surfaces, like rubber.
  • the racks could be used to brake a rotating pinion either in terms of slowing down its rotation or preventing rotation altogether.
  • the actuators were hydraulic, reduction of fluid flow through the actuator could slow pinion rotation, or prevention of fluid flow through the actuator could prevent pinion rotation. Further modifications will be apparent to those skilled in the art without departing from the scope of the present invention.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transmission Devices (AREA)

Abstract

The invention relates to a rack and pinion rotary drive. The drive comprises at least two racks 10,20 adapted to reciprocate linearly between first and second position. A pinion 1 is provided having at least one rack engaging member 2 over an arcuate part of the periphery of the pinion and at least one non- rack engaging member 3 over the other arcuate part of the periphery of the pinion. In use the racks being aligned around the pinion such that each rack sequentially is adjacent with and engages a rack engaging member to rotate the pinion as the rack moves from the first to the second position, and disengages from the rack engaging member as the pinion rotates and is adjacent a non-rack engaging member as the rack moves from the second to the first position.

Description

Title: Rack and Pinion Rotary Drive
The present invention relates to a rack and pinion rotary drive.
Rack and pinion rotary actuators are well known for converting linear motion into rotary motion. Rotary motion is obtained by applying fluid or air under pressure to a piston(s) located inside a cylinder. Movement of the piston drives a linear gear rack, which in turn drives a pinion gear mated to it, imparting rotary motion to the output shaft. The output shaft is located and supported between two bearings and is connected either directly to the load, or via a coupling or by linkage.
Various types of rack and pinion rotary actuators are known. These rotary actuators are available in various sizes and torque outputs and may be powered by either air or hydraulic fluid under pressure. One limiting factor which rack and pinion rotary actuators have in common is a limited degree of rotation. This degree of rotation is determined by rack length and pinion diameter. Typical standard degrees of rotation offered are 90, 180, 360 and 720 degrees.
It has been known provide continuous rotation of a pinion by driving the pinion with a pair of reciprocating racks which are mechanically engaged and disengaged with the pinion such that a rack only drives the pinion in one direction. A problem with this construction is that the mechanism for engagement and disengagement is complicated. The invention seeks to provide a solution.
According to the present invention there is provided a rack and pinion rotary drive comprising: a) at least two racks adapted to reciprocate linearly between first and second position, b) a pinion having at least one rack engaging member over an arcuate part of the periphery of the pinion and at least one non- rack engaging member over the other arcuate part of the periphery of the pinion, in use the racks being aligned around the pinion such that each rack sequentially is adjacent with and engages a rack engaging member to rotate the pinion as the rack moves from the first to the second position, and disengages from the rack engaging member as the pinion rotates and is adjacent a non-rack engaging member as the rack moves from the second to the first position.
The or each rack engaging member may be teeth on the periphery of the pinion which engage with teeth on a rack, the non-rack engaging member may be a toothless periphery of the pinion.
Preferably as one rack disengages from the rack engaging member, another rack engages with the rack engaging member so providing continuous rotational drive to the pinion.
In one embodiment there are two racks and one rack engaging member over a first semicircular arc of the pinion, and said pinion having a non- rack engaging member over the remaining semicircular arc of the pinion. The or each rack may be driven from the first to the second position and vice versa hydraulically, pneumatically, mechanically or electrically, or combinations thereof.
An embodiment of the invention will now be described with reference to Figures IA to IE showing schematic sequential views of the mechanism.
Referring to the drawings there is shown a pinion 1 having a rack engaging member in the form of an array of teeth 2 over a first semi-circular arc of the pinion, and a non-rack engaging member in the form of a toothless periphery 3 over the remaining semicircular arc of the pinion.
A first rack 10 with teeth 1OA is driven linearly by an actuator 11 from a first withdrawn position (see Figure ID) to a second expanded position (see Figure 1C), and back to a first withdrawn position (see Figure ID).
A second rack 20 with teeth 2OA is driven linearly by an actuator 21 from a first withdrawn position (see Figure IB) to a second expanded position (see Figure IA), and back to a first withdrawn position (see Figure IB).
The invention operates as follows. As shown in Figure IA, rack 10 is in the first position with its teeth 1OA adjacent and just coming into engagement with the teeth 2 on pinion 1. At the same time rack 21 is in the second position with its teeth 2OA just disengaging from teeth 2 on pinion 1.
As shown in Figure IB, actuator 11 starts to expand rack 10 towards its second position with its teeth 1OA adjacent and engaging teeth 2 on pinion 1, so rotating pinion 1. Meantime actuator 21 withdraws rack 20 to its first position with its teeth 2OA adjacent toothless periphery 3 of pinion 1, so its does not rotate pinion 1.
As shown in Figure 1C, rack 20 is in the first position with its teeth 2OA adjacent and just coming into engagement with the teeth 2 on pinion 1. At the same time rack 10 is in the second position with its teeth 1OA just disengaging from teeth 2 on pinion 1.
As shown in Figure ID, actuator 21 starts to expand rack 20 towards its second position with its teeth 2OA adjacent and engaging teeth 2 on pinion 1, so rotating pinion 1. Meantime actuator 11 withdraws rack 10 to its first position with its teeth 1OA adjacent toothless periphery 3 of pinion 1, so its does not rotate pinion 1.
As shown in Figure IE, rack 10 is back again in the first position with its teeth 1OA adjacent and just coming into engagement with the teeth 2 on pinion 1. At the same time rack 21 is back again in the second position with its teeth 2OA just disengaging from teeth 2 on pinion 1. From the above it will be seen that each rack sequentially is adjacent with and engages a rack engaging member to rotate the pinion as the rack moves from the first to the second position, and disengages from the rack engaging member as the pinion rotates and is adjacent a non- rack engaging member as the rack moves from the second to the first position.
Racks 10,20 may be driven by actuators from the first to the second position and vice versa hydraulically or pneumatically. Alternatively racks 10,20 may be driven mechanically or electrically. Combinations of hydraulic, pneumatic, mechanical and electrical movement are also possible.
The invention may take a form different to that specifically described above. For example more than two racks may be used to drive the pinion. For example four rack could drive a rack engaging member over a quarter of the periphery of the pinion. Also the pinion may have more than one rack engaging member and have more than one rack non-engaging member. Such multiple rack engaging members may be axially spaced over the pinion. The rack and pinion may engage by means other than teeth, e.g. engaging friction surfaces, like rubber.
It will also be appreciated that the racks could be used to brake a rotating pinion either in terms of slowing down its rotation or preventing rotation altogether. For example if the actuators were hydraulic, reduction of fluid flow through the actuator could slow pinion rotation, or prevention of fluid flow through the actuator could prevent pinion rotation. Further modifications will be apparent to those skilled in the art without departing from the scope of the present invention.

Claims

1. A rack and pinion rotary drive comprising: a) at least two racks adapted to reciprocate linearly between first and second position, b) a pinion having at least one rack engaging member over an arcuate part of the periphery of the pinion and at least one non- rack engaging member over the other arcuate part of the periphery of the pinion, in use the racks being aligned around the pinion such that each rack sequentially is adjacent with and engages a rack engaging member to rotate the pinion as the rack moves from the first to the second position, and disengages from the rack engaging member as the pinion rotates and is adjacent a non-rack engaging member as the rack moves from the second to the first position.
2. A rack and pinion rotary drive according to claim 1, wherein the or each rack engaging member is teeth on the periphery of the pinion which engage with teeth on a rack, and the non-rack engaging member is a toothless periphery of the pinion.
3. A rack and pinion rotary drive according to claim 1 or 2, wherein as one rack disengages from the rack engaging member, another rack engages with the rack engaging member so providing continuous rotational drive to the pinion.
4. A rack and pinion rotary drive according to any preceding claim, wherein there are two racks and one rack engaging member over a first semicircular arc of the pinion, and said pinion having a non- rack engaging member over the remaining semicircular arc of the pinion.
5. A rack and pinion rotary drive according to any preceding claim, wherein the or each rack is driven from the first to the second position and vice versa hydraulically, pneumatically, mechanically or electrically, or combinations thereof.
6. A rack and pinion rotary drive substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
PCT/EP2008/063497 2007-10-12 2008-10-08 Rack and pinion rotary drive WO2009047279A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0719947A GB0719947D0 (en) 2007-10-12 2007-10-12 Rack and pinion rotary drive
GB0719947.4 2007-10-12

Publications (2)

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WO2009047279A2 true WO2009047279A2 (en) 2009-04-16
WO2009047279A3 WO2009047279A3 (en) 2009-12-30

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WO (1) WO2009047279A2 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015107107A1 (en) * 2014-01-16 2015-07-23 MAQUET GmbH Device for linearly moving a patient support surface using a hydraulic cylinder and a gear arrangement
CN106514695A (en) * 2016-11-30 2017-03-22 合肥瑞硕科技有限公司 Device used for driving robot joint to rotate

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2608711A1 (en) * 1986-12-17 1988-06-24 Goulet Michel Device for converting a reciprocating linear movement into a rotational movement
US4941396A (en) * 1987-11-27 1990-07-17 Mccabe Peter J Reciprocating double-ended piston
CN1061073A (en) * 1990-10-31 1992-05-13 王军 Internal-combustion engine
CA2149999C (en) * 1995-05-23 1999-02-16 Pierre Charbonneau Rack and pinion mechanism for the conversion of reciprocating motion to rotational motion

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2608711A1 (en) * 1986-12-17 1988-06-24 Goulet Michel Device for converting a reciprocating linear movement into a rotational movement
US4941396A (en) * 1987-11-27 1990-07-17 Mccabe Peter J Reciprocating double-ended piston
CN1061073A (en) * 1990-10-31 1992-05-13 王军 Internal-combustion engine
CA2149999C (en) * 1995-05-23 1999-02-16 Pierre Charbonneau Rack and pinion mechanism for the conversion of reciprocating motion to rotational motion

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015107107A1 (en) * 2014-01-16 2015-07-23 MAQUET GmbH Device for linearly moving a patient support surface using a hydraulic cylinder and a gear arrangement
CN105848622A (en) * 2014-01-16 2016-08-10 迈柯唯有限公司 Device for linearly moving a patient support surface using a hydraulic cylinder and a gear arrangement
US10912696B2 (en) 2014-01-16 2021-02-09 MAQUET GmbH Device for linearly moving a patient support surface using a hydraulic cylinder and a gear arrangement
CN106514695A (en) * 2016-11-30 2017-03-22 合肥瑞硕科技有限公司 Device used for driving robot joint to rotate

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Publication number Publication date
WO2009047279A3 (en) 2009-12-30
GB0719947D0 (en) 2007-11-21

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