GB2375805A - Electric motor actuator having an eccentric double pinion gear - Google Patents
Electric motor actuator having an eccentric double pinion gear Download PDFInfo
- Publication number
- GB2375805A GB2375805A GB0112534A GB0112534A GB2375805A GB 2375805 A GB2375805 A GB 2375805A GB 0112534 A GB0112534 A GB 0112534A GB 0112534 A GB0112534 A GB 0112534A GB 2375805 A GB2375805 A GB 2375805A
- Authority
- GB
- United Kingdom
- Prior art keywords
- electric motor
- teeth
- double pinion
- actuator according
- output member
- Prior art date
- Legal status (The legal status 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 status listed.)
- Withdrawn
Links
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
- F16H1/00—Toothed gearings for conveying rotary motion
- F16H1/28—Toothed gearings for conveying rotary motion with gears having orbital motion
- F16H1/32—Toothed gearings for conveying rotary motion with gears having orbital motion in which the central axis of the gearing lies inside the periphery of an orbital gear
-
- 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
- F16H1/00—Toothed gearings for conveying rotary motion
- F16H1/28—Toothed gearings for conveying rotary motion with gears having orbital motion
- F16H2001/2881—Toothed gearings for conveying rotary motion with gears having orbital motion comprising two axially spaced central gears, i.e. ring or sun gear, engaged by at least one common orbital gear wherein one of the central gears is forming the output
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
Abstract
An electric motor actuator includes an electric motor 14 having an output shaft 12, and a drive mechanism comprising a double pinion 10 mounted eccentrically on the output shaft 12. The double pinion 10 having first and second sets of teeth 16,18, the number of teeth in one set 18 being greater than the number of teeth in the other set 16, the first set of teeth 16 meshes with a fixed internal gear 20, the second set of teeth meshes with an output member 22. The number of teeth on the fixed internal gear 20 and the internal gear 24 being equal to the number of teeth on the first and second sets of teeth 16,18 of the double pinion 10, respectively, plus 2 e k teeth where " e " is the eccentricity of rotation of the double pinion 10 and "k" is a constant proportional to the pitch of the teeth on the double pinion.
Description
<Desc/Clms Page number 1>
CLUTCH AND GEAR ACTUATORS The present invention relates to clutch and gear actuators and in particular electric motor actuators for control of a clutch or a gear selector mechanism of an automated transmission systems for a motor vehicle.
Electric motor actuators which are used to control the clutches and gear shifter mechanisms of automated transmission systems typically utilize a worm and worm gear drive mechanism to provide a high ratio reduction, for example as disclosed in GB2325036, GB2313885 and GB2309761 the disclosure of which explicit reference is made and whose content is expressly incorporated in the disclosure content of the present application, in order to convert the high speed, relatively low torque drive of the electric motor into a slow speed relatively high torque required to actuate a clutch or gear shifter mechanism. Typically the drive ratios of such mechanisms are of the order of 50: 1 to 60: 1.
The worm gear drives utilized hitherto have the disadvantage that they are relatively large and present serious difficulties with regard to the packaging constraints encountered in automated transmission systems for motor vehicles.
The present invention utilizes a high ratio drive of concentric construction to overcome the disadvantages of the worm drive used hitherto.
In accordance with one aspect of the present invention an electric motor actuator for control of a clutch or gear selector mechanism of a motor vehicle; includes an electric motor, an output shaft of the electric motor, and a drive mechanism comprising a double pinion mounted eccentrically on the output shaft of the electric motor and rotatable relative thereto, the double pinion having first and second sets of teeth, the number of teeth in
<Desc/Clms Page number 2>
one set being greater than the number of teeth in the other set, the first set of teeth meshing with the teeth of a fixed internal gear, the second set of teeth meshing with the teeth of an internal gear mounted for rotation with an output member which is mounted for rotation coaxially of the output shaft of the electric motor, the number of teeth on the fixed internal gear and the internal gear on the output member being equal to the number of teeth on the first and second sets of teeth of the double pinion, respectively, plus 2sk teeth where"E"is the eccentricity of rotation of the double pinion and"k"is a constant inversely proportional to the pitch of the teeth.
With the drive mechanism described above ;
the drive ratio i = N (M + n) n (N-M)
where M = the number of teeth in the first set of teeth of the double pinion ;
N = the number of teeth in the first set of teeth of the double pinion; and n = 2eu.
The values of M, N and n must consequently be selected to provide the required drive ratio which will typically be from 50: 1 to 60: 1.
The drive used in the present invention is particularly advantageous for use with shift drums for example as disclosed in GB2308874 and GB2311829 the disclosures of which explicit reference is made and whose content is expressly incorporated in the disclosure content of the present application, in which the electric motor and drive mechanism may be mounted coaxially within the shift drum. The drive mechanism
<Desc/Clms Page number 3>
described above may alternatively be used with linear actuators, for example ball and screw actuators or rack and pinion mechanisms.
A further advantage of the present invention is that the actuators may be made self locking with minimal increase in the internal friction of the drive mechanism.
The invention is now described by way of example only, with reference to the accompany drawings, in which: Figure 1 illustrates diagramatically a drive mechanism utilized in clutch or gear actuators according to the present invention; Figure 2 shows in sectional side elevation a shift drum actuator in accordance with the present invention; Figure 3 shows in sectional side elevation a ball and screw actuator in accordance with the present invention; and Figure 4 shows in sectional side elevation a rack and pinion actuator in accordance with the present invention.
As illustrated in figure 1, a double pinion 10 is mounted on the output shaft 12 of an electric motor 14. The double pinion 10 is mounted rotatably on the shaft 12 eccentrically thereof, the axis of rotation of the pinion 10 being offset from the axis of rotation of the shaft by the eccentricity s.
The double pinion 10 defines a primary pinion 16 having N teeth and a secondary pinion 18 having M teeth. The primary pinion 16 meshes with an internal gear ring 20 mounted in fixed relationship coaxially of the electric motor 14. The internal gear ring 20 has N + n teeth, where
<Desc/Clms Page number 4>
n = 2sk, where"k"is a constant depending on the pitch of the teeth.
An output member 22 is mounted for rotation coaxially of the output shaft 10 of the electric motor 14. The secondary pinion 18 meshes with an internal gear 24 on the output member 22, the internal gear 24 having M + n teeth.
The drive ratio i for the gear mechanism described above;
The values of M, N and n are selected to provide and appropriate gear ratio which is preferably of the order of 40: 1 to 60: 1, for example as illustrated in table 1 below.
Table 1
Number of Teeth Drive M N n ratio i 22 20 5 -54. 0* 24 22 5 -63. 8 * 29 35 3 62. 2 23 29 3 41. 9 18 22 3 38. 5 18 22 2 55. 0 * negative value signifies rotation of output member in opposite direction to motor shaft.
The drive mechanism described above also has the advantage that friction in the drive mechanism will prevent loads applied to the output member from reversing the drive, so that the drive mechanism may be self locking.
<Desc/Clms Page number 5>
This is particularly advantageous with clutch actuators where the actuator must, for example, hold members of the clutch apart while the clutch is disengaged, against the'spring load urging the members into engagement.
According to a preferred embodiment as described in detail below, an eccentric is mounted on the output shaft of the electric motor 14, the double pinion 12 being mounted on the eccentric by means of a sliding bearing. With this construction:
the minimum coefficient of friction for self locking Il = s\ (N-R) R (N + s) where R = the radius of the eccentric.
From the above it follows that the smaller the eccentricity the smaller the friction required for self locking. Moreover for clutch and gear actuators a small eccentricity is required in order to provide the drive ratios required.
Figure 2 illustrates a gear shift drum assembly utilizing the drive mechanism described above. The electric motor 14 is mounted on a cylindrical housing 30, the motor 14 being secured to an internal flange 32 located adjacent one end 34 of the housing 30. An external flange 35 at the other end of housing 30, is adapted to be secured to, for example, a gear box housing. The fixed internal gear ring 20 is provided at end 34 of housing 30.
An eccentric 36 is mounted on the output shaft 1 2 of the electric motor 14, the double pinion 10 being rotatably mounted on the eccentric 36 by means of a rolling bearing 38. The primary pinion 16 of double pinion 10 meshes with the internal gear ring 20, so that upon rotation if shaft 12, the double pinion 10 will roll around the internal gear ring 20.
A shift drum 40 is rotatably mounted on the outer diameter of the cylindrical housing 30 by means of rolling bearings 42. The end of the
<Desc/Clms Page number 6>
shift drum 40 remote from flange 36 of housing 30 is closed, the closed end of the shift drum 40 being rotatably mounted on the output shaft 12 of electric motor 14, by'rolling bearing 44. The internal gear ring 24 is provided on the shift drum 40 adjacent the closed end there of, the internal gear ring 24 meshing with the secondary pinion 18 of the double pinion 10.
When the electric motor 14 drives shaft 12, so that the double pinion 10 rolls around the internal gear 20, engagement of the secondary pinion 18 with the internal gear 24 will cause the shift drum 40 to rotate, the drive ratio typically being of the order of 40: 1 to 60: 1.
The linear drive illustrated in figure 3 may typically be used to control movement of a piston of an hydraulic master cylinder of the type disclosed in GB2325036, GB2313885 and GB2309761, which in turn will supply hydraulic pressure to a clutch slave cylinder to control engagement and disengagement of a clutch. Alternatively linear actuators of this type may be used to control engagement and disengagement of a clutch, or selection of a gear ratio, via a suitable mechanical linkage mechanism or cable drive.
In the linear actuator illustrated in figure 3, the double pinion 10 is rotatably mounted on an eccentric 36 mounted on the output shaft 12 of the electric motor 14, in similar manner to that described with reference to figure 3. The pinion 10 is however mounted on the eccentric 36 by means of a sliding bearing, in order to provide sufficient friction in the drive to prevent wind back of the linear actuator when a load is applied thereto.
The motor 14 is secured to a concentric housing 50 which defines the fixed internal gear ring 20 which meshes with the primary pinion 16 of double pinion 10. An annular output member 22 is rotatably mounted to
<Desc/Clms Page number 7>
the housing 50 and output shaft 12 of motor 14 by means of rolling bearings 52,54. The output member 50 defines the internal gear ring 24 which meshes with the secondary pinion 18.
The end 56 of output member 50 remote from motor 14 defines the internal threaded portion of a ball screw actuator 58. An outer threaded portion 60 of the ball screw actuator 58 is mounted coaxially of the inner portion 56, with a series of balls 62 located therebetween, in the thread formation defined by the inner and outer portions 56,60. The outer portion 60 of the ball screw actuator 58 has a plunger formation 64 which extends through an end wall 66 of housing 50, the plunger formation 64 being moveable axially of the housing 50 but constrained from rotation relative thereto. The plunger formation 64, which may be connected directly or indirectly to the piston of an hydraulic master cylinder, will thereby be moved axially by rotation of the output member 22, when driven by the electric motor 14.
A compensating spring 68 acts between the output member 22 and outer portion 60 of the ball screw actuator 58, urging the outer portion 60 towards the end wall 66 of housing 50. The compensating spring 68 will thereby oppose the load applied by the clutch spring. Typically, the compensating spring 68 will be arranged to be under compression when the clutch is fully engaged and the ball screw actuator 58 is at a limit of its movement away from the closed end of housing 50. The load applied by compensating spring 68 will thereby assist the electric motor 14 as the ball screw actuator 58 is driven to disengage the clutch. In this manner a smaller electric motor 14 may be used, than would be required if a compensating spring 68 were not present.
Figure 4 illustrates a rack and pinion drive actuator, similar to the actuator illustrated in figure 3, in which the output member 22 defines a pinion 70 which engages a rack 72 which extends transversely of the housing 50.
<Desc/Clms Page number 8>
Various modifications may be made without departing from the invention.
For example while in the above embodiments the double pinion is rotatably mounted in the output shaft of the electric motor on an eccentric, alternatively, the output shaft may be cranked.
Also with regard to the ball screw actuator described with reference to figure 3, the output member of the drive mechanism may define to outer threaded portion of the ball screw rather than the inner portion.
The patent claims submitted with the application are proposed formulations without prejudice to the achievement of further patent protection. The applicant reserves the right to submit claims for further combinations of characteristics, previously only disclosed in the description and/or drawings.
References back used in sub-claims refer to the further development of the subject of the main claim by the characteristics of the respective subclaim ; they are not to be understood as a waiver with regard to achieving independent item protection for the combination of characteristics in the related sub-claims.
Since the subject of the sub-claims can form separate and independent inventions with reference to the prior art on the priority date, the applicant reserves the right to make them the subject of independent claims or of division declarations. Furthermore, they may also contain independent inventions which demonstrate a design which is independent of one of the objects of the preceding sub-claims.
The embodiments are not to be considered a restriction of the invention.
Rather, a wide range of amendments and modifications is possible within the scope of the current disclosure, especially those variations, elements
<Desc/Clms Page number 9>
and combinations and/or materials which, for example, the expert can learn by combining individual ones together with those in the general description and embodiments in addition to characteristics and/or elements or process stages described in the claims and contained in the drawings with the aim of solving a task thus leading to a new object or new process stages or sequences of process stages via combinable characteristics, even where they concern manufacturing, testing and work processes.
Claims (14)
- CLAiMS 1. An electric motor actuator for control of a clutch or gear selector mechanism of a motor vehicle including; an electric motor, an output shaft of the electric motor, and a drive mechanism comprising a double pinion mounted eccentrically on the output shaft of the electric motor and rotatable relative thereto, the double pinion having first and second sets of teeth, the number of teeth in one set being greater than the number of teeth in the other set, the first set of teeth meshing with the teeth of a fixed internal gear, the second set of teeth meshing with the teeth of an internal gear mounted for rotation with an output member which is mounted for rotation coaxially of the output shaft of the electric motor, the number of teeth on the fixed internal gear and the internal gear on the output member being equal to the number of teeth on the first and second sets of teeth of the double pinion, respectively, plus 2ek teeth where"" is the eccentricity of rotation of the double pinion and"k"is a constant inversely proportional to the pitch of the teeth.
- 2. An electric motor actuator according to claim 1 in which the drive mechanism has a drive ratio of from 40: 1 to 60: 1.
- 3. An electric motor actuator according to claim 1 or 2 in which the double pinion is rotatably mounted on an eccentric which is mounted for rotation with the output shaft of the electric motor.
- 4. An electric motor actuator according to any one of the preceding claims in which the double pinion is rotatably mounted eccentrically of the input shaft by means of a rolling bearing.
- 5. An electric motor actuator according to any one of the preceding claims in which the actuator is self locking.<Desc/Clms Page number 11>
- 6. An electric motor actuator according to claim 5 in which the double pinion is rotatably mounted eccentrically of the input shaft by means of a sliding bearing.
- 7. An electric motor actuator according to any one of the preceding claims in which the output member is a shift drum which is adapted to control movement of a gear shift mechanism.
- 8. An electric motor actuator according to claim 7 in which the electric motor is mounted inside a cylindrical housing, the cylindrical housing defining the fixed internal gear ring, the shift drum being rotatably mounted on the external diameter of the cylindrical housing, the relatively rotatable internal gear ring being provided on an internal diameter of the shift drum.
- 9. An electric motor actuator according to any one of claims 1 to 6 in which the output member drives a screw actuator.
- 10. An electric motor actuator according to claim 9 in which the output member drives ball screw actuator, the ball screw actuator comprising an inner and an outer threaded portion with a series of balls located in the thread formation defined therebetween, the output member defining one of the threaded portions of the ball screw actuator, the other threaded portion if the ball screw actuator being moveable axially but constrained rotationally with regard to the output member.
- 11. An electric motor actuator according to claim 9 or 10 in which a compensating spring is provided between inner and outer threaded portions of the screw actuator.
- 12. An electric motor actuator according to any one of claims 1 to 6 in which the output member drives a rack and pinion mechanism.<Desc/Clms Page number 12>
- 13. An electric motor actuator according to claim 12 in which the output member defines a pinion, said pinion meshing with a rack mounted transversely of the axis of rotation of said pinion.
- 14. An electric motor actuator substantially as described herein with reference to and as shown in figures 1 to 4 of the accompanying drawings.
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0112534A GB2375805A (en) | 2001-05-23 | 2001-05-23 | Electric motor actuator having an eccentric double pinion gear |
PCT/DE2002/001817 WO2002095261A2 (en) | 2001-05-23 | 2002-05-21 | Clutch and shift actuators |
FR0206157A FR2825130B1 (en) | 2001-05-23 | 2002-05-21 | CLUTCH AND GEARBOX ACTUATORS |
DE10222339A DE10222339A1 (en) | 2001-05-23 | 2002-05-21 | Reduction gear for electric motor actuator element has numbers of teeth on fixed inner gear wheel and output element inner gear wheel differing from pinion sets depending on rotation eccentricity |
DE10292233T DE10292233D2 (en) | 2001-05-23 | 2002-05-21 | Clutch and shift actuators |
IT2002MI001110A ITMI20021110A1 (en) | 2001-05-23 | 2002-05-22 | CLUTCH ACTUATORS AND GEAR CHANGE OF A TRANSMISSION SYSTEM OR AUTOMATIC GEARBOX FOR A VEHICLE |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0112534A GB2375805A (en) | 2001-05-23 | 2001-05-23 | Electric motor actuator having an eccentric double pinion gear |
Publications (2)
Publication Number | Publication Date |
---|---|
GB0112534D0 GB0112534D0 (en) | 2001-07-11 |
GB2375805A true GB2375805A (en) | 2002-11-27 |
Family
ID=9915137
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB0112534A Withdrawn GB2375805A (en) | 2001-05-23 | 2001-05-23 | Electric motor actuator having an eccentric double pinion gear |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2375805A (en) |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4014224A (en) * | 1973-10-12 | 1977-03-29 | Pitts Drive, Inc. | Speed differential planetary gear train |
US4016780A (en) * | 1975-03-03 | 1977-04-12 | Trochoidal Gear Technology, Inc. | Hypotrochoidal cluster gear drives |
GB2107424A (en) * | 1981-10-05 | 1983-04-27 | Metal Box Co Ltd | Power-operated can opener having epicyclic reduction gearing |
US4446752A (en) * | 1981-04-23 | 1984-05-08 | Advanced Energy Concepts '81, Ltd. | Epicycloidal gears and gear tooth arrangement therefor |
GB2229509A (en) * | 1989-02-07 | 1990-09-26 | James * Hickey Dennis | Epicyclic friction gearing |
-
2001
- 2001-05-23 GB GB0112534A patent/GB2375805A/en not_active Withdrawn
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4014224A (en) * | 1973-10-12 | 1977-03-29 | Pitts Drive, Inc. | Speed differential planetary gear train |
US4016780A (en) * | 1975-03-03 | 1977-04-12 | Trochoidal Gear Technology, Inc. | Hypotrochoidal cluster gear drives |
US4446752A (en) * | 1981-04-23 | 1984-05-08 | Advanced Energy Concepts '81, Ltd. | Epicycloidal gears and gear tooth arrangement therefor |
GB2107424A (en) * | 1981-10-05 | 1983-04-27 | Metal Box Co Ltd | Power-operated can opener having epicyclic reduction gearing |
GB2229509A (en) * | 1989-02-07 | 1990-09-26 | James * Hickey Dennis | Epicyclic friction gearing |
Also Published As
Publication number | Publication date |
---|---|
GB0112534D0 (en) | 2001-07-11 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |