EP1957342A1 - Electrical power steering assembly - Google Patents

Electrical power steering assembly

Info

Publication number
EP1957342A1
EP1957342A1 EP06820425A EP06820425A EP1957342A1 EP 1957342 A1 EP1957342 A1 EP 1957342A1 EP 06820425 A EP06820425 A EP 06820425A EP 06820425 A EP06820425 A EP 06820425A EP 1957342 A1 EP1957342 A1 EP 1957342A1
Authority
EP
European Patent Office
Prior art keywords
housing
steering assembly
electric power
power assisted
assembly according
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Withdrawn
Application number
EP06820425A
Other languages
German (de)
French (fr)
Inventor
Michael Lawson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
TRW Ltd
Original Assignee
TRW Ltd
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 TRW Ltd filed Critical TRW Ltd
Publication of EP1957342A1 publication Critical patent/EP1957342A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D1/00—Steering controls, i.e. means for initiating a change of direction of the vehicle
    • B62D1/02—Steering controls, i.e. means for initiating a change of direction of the vehicle vehicle-mounted
    • B62D1/16—Steering columns
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0409—Electric motor acting on the steering column

Definitions

  • This invention relates to improvements in electrical power assisted steering systems.
  • a steering system in which an electrical motor is used to apply an assistance torque to a part of a steering assembly so as to assist the driver in steering a vehicle.
  • a sensor is provided which measures the torque applied to the steering shaft through the wheel by the driver, and from that generates an assistance torque value.
  • the motor is then driven to apply an assistance torque to the steering shaft equal to the torque value. If this torque has the same sense as the torque demanded by the driver the effect is to make it easier for the driver to turn the wheel.
  • the motor typically acts upon a section of steering shaft through a gearbox and optionally a clutch.
  • the present invention provides, therefore, an electric power assisted steering assembly comprising a housing which contains an electric motor, a motor drive circuit and a gearbox, the housing including an opening through which a portion of a steering shaft can pass for connection to the motor through the gearbox, and in which an earthing means is provided which is connected to the housing and which is resiliently biased into contact with the portion of the steering shaft so as to electrically earth the steering shaft to the housing.
  • the housing may have a single compartment which contains the motor and the gearbox and the drive circuit. Alternatively this may comprises more than one compartment, perhaps connected together to form a single unit.
  • the motor drive circuit, motor and gearbox may be in different compartments for example.
  • the housing may be metal or any other suitable conducting material. It may, for example, be of cast aluminium or steel construction.
  • the portion of the steering shaft may form part of a telescopic steering shaft assembly and may be supported by one or more bearings journalled to the housing.
  • the or each bearing may also provide additional earthing to the housing.
  • It may comprise a gearbox output shaft that can be coupled, directly or indirectly, to a port of a steering shaft assembly.
  • the earthing means may comprise a flexible electrically conductive component which is fixed at in one region to the housing such that it contacts the steering column at another region. It may be fixed to the housing at one end and contact the column at or near its other end.
  • the earthing means may be metal or may be another electrical conductor. It may be coated with a highly conductive material such as silver or gold to provide good electrical contact to the steering shaft. The portion of shaft that it contacts may similarly be coated with a highly conductive material such as silver or gold.
  • the earthing means may be secured to the housing by a rivet, a bolt, a screw, a weld or any other suitable fastening device or method.
  • a single earthing means is provided which is located alongside or within the opening in the housing. It is preferably arranged such that when the column is inserted the earthing means is deflected such that it is always biased into contact with the column.
  • the earthing means may comprise a strip metal component whose flexibility is determined by its thickness. It may be bent such that the component acts as a spring to urge it into contact with the steering shaft.
  • the earthing means may comprise a contact from an electrical relay or perhaps from an electrical motor.
  • Such contacts are readily available and relatively low cost and provide an elegant solution to providing an earthing means as required by the invention. It is simpler and easier to connect such a contact to the housing than to develop a bespoke contact which may involve greater cost.
  • the earthing means preferably contacts the steering shaft at a point adjacent the opening in the cover.
  • the shaft may include a step change in diameter adjacent the opening, and the earthing means may contact the face defined by this step change.
  • this face faces away from the housing, i.e. towards the cover end, so that as the cover is introduced to the housing the earthing means first contacts the face and is then pressed down onto it as the cover is tightened.
  • This step face is conveniently defined by an end of a quill shaft formed in the steering shaft which forms part of a torque sensor located within the housing.
  • Figure 1 is a schematic view of an electric power assisted steering system
  • Figure l (b) is a view of a practical embodiment of a steering system of the kind shown in Figure 1 ;
  • Figure 2 is a view of an end cover for a housing of a steering system of the kind shown in Figure 2 constructed in accordance with a first aspect of the present invention and prior to connection of the assembly to a steering shaft;
  • FIG 3 is an enlarged view of the earthing means prior to connection to the cover of the housing as shown in Figure 2;
  • Figure 4 shows in detail the deformation of the earthing means with the steering shaft in position; and Figure 5 is an enlarged view of the contact between the earthing means and the steering shaft.
  • the assembly of Figures 1 and 2 comprises a housing 10 which supports an electric motor 1.
  • the housing 10 accommodates a drive circuit 7 for the motor 1 and a gearbox 4 (shown in Figure 1 only) connected to an output shaft 2 of the motor.
  • An optional clutch 3 may also be provided.
  • An end cover 11 for the housing 10 can be removed for access to the gearbox and includes a central opening 12 (seen best in Figure 2) through which a portion of steering shaft 5 passes and engages the gearbox.
  • the shaft 5 is supported in at least one bearing race.
  • the end cover 11 is shown in more detail in Figure 2. It comprises a cast metal component which has a central opening 12 as described. The opening is annular and has a diameter that is slightly larger than the outside diameter of the steering column shaft 5 that passes through it.
  • An earthing means 13 is provided in the form of a bent metal sheet which is riveted to the cover by the opening by two rivets 14. A part of the sheet protrudes into the opening.
  • the earthing means is shown in more detail in Figure 3. It has two arms 13a, 13b that are resiliently deformable. Both arms project radially inwards towards the centre of the opening and provide two regions of contact to the steering shaft. As shown in Figure 4, these arms contact the steering shaft by an interference fit when the shaft is in its position of use. A highly conductive material such as silver is provided on the end of the arms where they contact the shaft.
  • the contact between the arms 13a, 13b of the earthing means 13 and the shaft 5 can best be seen in Figure 5.
  • An annular lip 5a on the shaft 5 presses up on the two arms 13a, 13b to deflect them approximately 0.7mm towards the cover for the housing. This deflection ensures a firm contact and that any run out in the shaft lip is accommodated as the shaft rotates.
  • the bent metal sheet 13 provides a good reliable earth connection from the housing 10 to the shaft 5.
  • the housing 5 should be of metal construction and the portion of shaft 5 also metal. Alternatively, some other conductive material could be used to provide earth continuity.
  • the housing should also be earthed to a part of a vehicle when in use.
  • Providing the contact ensures that a good earth is present to the column, preventing electromagnetic radiation being emiited by the column. This acts in addition to the earth contact that may otherwise be present, perhaps through the bearing race supporting the shaft.
  • the metal sheet is preferably relatively thin so that it will be resiliently deformed by the shaft without providing a great amount of resistance and hence friction between them.
  • One or more bends may be placed in the sheet so as to control the way it deforms and cause it to act as a spring.
  • a contact taken from an electrical relay, fixed in position on the housing, could be used as the earthing means.
  • a bespoke sheet metal component, or other component could be used depending on the application.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Power Steering Mechanism (AREA)

Abstract

An electric power assisted steering assembly comprises a housing (100) which contains an electric motor (1) having an opening (12) through which a portion (5) of the steering assembly can pass for connection to the motor through a gearbox also contained in the housing. An earthing means (13) is connected to the housing (10) and is resiliently biased into contact with the portions (5) of the steering assembly so as to electrically connect it to the housing (10).

Description

ELECTRICAL POWER STEERING ASSEMBLY
This invention relates to improvements in electrical power assisted steering systems.
It is known to provide a steering system in which an electrical motor is used to apply an assistance torque to a part of a steering assembly so as to assist the driver in steering a vehicle. Typically, a sensor is provided which measures the torque applied to the steering shaft through the wheel by the driver, and from that generates an assistance torque value. The motor is then driven to apply an assistance torque to the steering shaft equal to the torque value. If this torque has the same sense as the torque demanded by the driver the effect is to make it easier for the driver to turn the wheel. The motor typically acts upon a section of steering shaft through a gearbox and optionally a clutch.
There is a need to make the electrical power assisted steering system compact as it must fit either below the dashboard within the passenger cell of a vehicle or within the engine bay. Often the motor, the sensor and the gearbox though which the motor acts upon the steering assembly are housed within a single housing, or a multi-section housing. A portion of steering shaft protrudes from the housing and is supported by at least one bearing race. To prevent unwanted radiation from the motor or its drive circuit affecting other components nearby this housing is typically metal or magnetically shielded plastic and may be earthed to the chassis.
The applicant has appreciated that there is a potential weakness in the region where the steering shaft must enter this housing for connection to the gearbox and motor, and that electromagnetic radiation may escape in this region or may even be transmitted by the steering shaft itself. Whilst this is generally of little concern there may be some applications where any slight radiation of this kind could interfere with other equipment fitted to the vehicle. Up until now it has been thought that the earth connection made between the steering shaft and the housing through the bearing provides sufficient earthing and in general it does.
The present invention provides, therefore, an electric power assisted steering assembly comprising a housing which contains an electric motor, a motor drive circuit and a gearbox, the housing including an opening through which a portion of a steering shaft can pass for connection to the motor through the gearbox, and in which an earthing means is provided which is connected to the housing and which is resiliently biased into contact with the portion of the steering shaft so as to electrically earth the steering shaft to the housing. The housing may have a single compartment which contains the motor and the gearbox and the drive circuit. Alternatively this may comprises more than one compartment, perhaps connected together to form a single unit. The motor drive circuit, motor and gearbox may be in different compartments for example.
The housing may be metal or any other suitable conducting material. It may, for example, be of cast aluminium or steel construction.
The portion of the steering shaft may form part of a telescopic steering shaft assembly and may be supported by one or more bearings journalled to the housing. The or each bearing may also provide additional earthing to the housing. It may comprise a gearbox output shaft that can be coupled, directly or indirectly, to a port of a steering shaft assembly. The earthing means may comprise a flexible electrically conductive component which is fixed at in one region to the housing such that it contacts the steering column at another region. It may be fixed to the housing at one end and contact the column at or near its other end.
The earthing means may be metal or may be another electrical conductor. It may be coated with a highly conductive material such as silver or gold to provide good electrical contact to the steering shaft. The portion of shaft that it contacts may similarly be coated with a highly conductive material such as silver or gold. The earthing means may be secured to the housing by a rivet, a bolt, a screw, a weld or any other suitable fastening device or method.
Preferably a single earthing means is provided which is located alongside or within the opening in the housing. It is preferably arranged such that when the column is inserted the earthing means is deflected such that it is always biased into contact with the column.
The earthing means may comprise a strip metal component whose flexibility is determined by its thickness. It may be bent such that the component acts as a spring to urge it into contact with the steering shaft.
The earthing means may comprise a contact from an electrical relay or perhaps from an electrical motor. Such contacts are readily available and relatively low cost and provide an elegant solution to providing an earthing means as required by the invention. It is simpler and easier to connect such a contact to the housing than to develop a bespoke contact which may involve greater cost.
The earthing means preferably contacts the steering shaft at a point adjacent the opening in the cover. In a most preferred arrangement the shaft may include a step change in diameter adjacent the opening, and the earthing means may contact the face defined by this step change. Preferably this face faces away from the housing, i.e. towards the cover end, so that as the cover is introduced to the housing the earthing means first contacts the face and is then pressed down onto it as the cover is tightened. This step face is conveniently defined by an end of a quill shaft formed in the steering shaft which forms part of a torque sensor located within the housing.
There will now be described, by way of example only, one embodiment of the present invention with reference to and as illustrated in the accompanying drawings of which:
Figure 1 is a schematic view of an electric power assisted steering system;
Figure l (b) is a view of a practical embodiment of a steering system of the kind shown in Figure 1 ;
Figure 2 is a view of an end cover for a housing of a steering system of the kind shown in Figure 2 constructed in accordance with a first aspect of the present invention and prior to connection of the assembly to a steering shaft;
Figure 3 is an enlarged view of the earthing means prior to connection to the cover of the housing as shown in Figure 2;
Figure 4 shows in detail the deformation of the earthing means with the steering shaft in position; and Figure 5 is an enlarged view of the contact between the earthing means and the steering shaft. The assembly of Figures 1 and 2 comprises a housing 10 which supports an electric motor 1. The housing 10 accommodates a drive circuit 7 for the motor 1 and a gearbox 4 (shown in Figure 1 only) connected to an output shaft 2 of the motor. An optional clutch 3 may also be provided. An end cover 11 for the housing 10 can be removed for access to the gearbox and includes a central opening 12 (seen best in Figure 2) through which a portion of steering shaft 5 passes and engages the gearbox. The shaft 5 is supported in at least one bearing race.
The end cover 11 is shown in more detail in Figure 2. It comprises a cast metal component which has a central opening 12 as described. The opening is annular and has a diameter that is slightly larger than the outside diameter of the steering column shaft 5 that passes through it. An earthing means 13 is provided in the form of a bent metal sheet which is riveted to the cover by the opening by two rivets 14. A part of the sheet protrudes into the opening.
The earthing means is shown in more detail in Figure 3. It has two arms 13a, 13b that are resiliently deformable. Both arms project radially inwards towards the centre of the opening and provide two regions of contact to the steering shaft. As shown in Figure 4, these arms contact the steering shaft by an interference fit when the shaft is in its position of use. A highly conductive material such as silver is provided on the end of the arms where they contact the shaft.
The contact between the arms 13a, 13b of the earthing means 13 and the shaft 5 can best be seen in Figure 5. An annular lip 5a on the shaft 5 presses up on the two arms 13a, 13b to deflect them approximately 0.7mm towards the cover for the housing. This deflection ensures a firm contact and that any run out in the shaft lip is accommodated as the shaft rotates. The bent metal sheet 13 provides a good reliable earth connection from the housing 10 to the shaft 5. For best effect the housing 5 should be of metal construction and the portion of shaft 5 also metal. Alternatively, some other conductive material could be used to provide earth continuity. The housing should also be earthed to a part of a vehicle when in use.
Providing the contact ensures that a good earth is present to the column, preventing electromagnetic radiation being emiited by the column. This acts in addition to the earth contact that may otherwise be present, perhaps through the bearing race supporting the shaft.
Many variations are possible within the scope of the invention. The metal sheet is preferably relatively thin so that it will be resiliently deformed by the shaft without providing a great amount of resistance and hence friction between them. One or more bends may be placed in the sheet so as to control the way it deforms and cause it to act as a spring. A contact taken from an electrical relay, fixed in position on the housing, could be used as the earthing means. Alternatively, a bespoke sheet metal component, or other component could be used depending on the application.
Also, whilst the embodiment shown uses two rivets to fix the contact to the housing cover, another form of connection could be used such as a soldered joint or a weld.

Claims

1. An electric power assisted steering assembly comprising a housing which contains an electric motor, a motor drive circuit and a gearbox, the housing including an opening through which a portion of a steering assembly can pass for connection to the motor through the gearbox, and in which an earthing means is provided which is connected to the housing and which is resiliently biased into contact with the portion of the steering assembly so as to electrically connect the portion to the housing.
2. An electric power assisted steering assembly according to claim 1 in which the housing may has more than one compartment connected together to form a single unit.
3. An electric power assisted steering assembly according to any preceding claim in which the housing is metal or any other suitable conducting material.
4. An electric power assisted steering assembly according to any preceding claim in which the portion of the steering assembly preferably is a portion of a steering column shaft which passes through the opening in the housing.
5. An electric power assisted steering assembly according to any preceding claim in which the earthing means comprises a flexible metal strip which is fixed at one region to the housing such that it contacts the steering column at another region.
6. An electric power assisted steering assembly according to claim 5 in which the strip is fixed to the housing at one end and contacts the column at or near its other end.
7. An electric power assisted steering assembly according to any preceding claim in which the earthing means is metal.
8 An electric power assisted steering assembly according to any preceding claim in which the earthing means is secured to the housing by a rivet, a bolt, a screw, a weld or any other suitable fastening device or method.
9. An electric power assisted steering assembly according to any preceding claim in which a single earthing means is provided which is located alongside or within the opening in the housing.
10. An electric power assisted steering assembly according to any preceding claim in which the earthing means is arranged such that when the column is inserted the earthing means is deflected such that it is always biased into contact with the column.
11. An electric power assisted steering assembly according to any preceding claim in which the earthing means comprises a contact from a relay.
EP06820425A 2005-12-06 2006-12-06 Electrical power steering assembly Withdrawn EP1957342A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0524837A GB0524837D0 (en) 2005-12-06 2005-12-06 Electrical power steering assemblies
PCT/GB2006/004541 WO2007066095A1 (en) 2005-12-06 2006-12-06 Electrical power steering assembly

Publications (1)

Publication Number Publication Date
EP1957342A1 true EP1957342A1 (en) 2008-08-20

Family

ID=35686142

Family Applications (1)

Application Number Title Priority Date Filing Date
EP06820425A Withdrawn EP1957342A1 (en) 2005-12-06 2006-12-06 Electrical power steering assembly

Country Status (3)

Country Link
EP (1) EP1957342A1 (en)
GB (1) GB0524837D0 (en)
WO (1) WO2007066095A1 (en)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB772682A (en) * 1954-06-23 1957-04-17 Thompson Prod Inc Improvements in and relating to power-assisted manual steering systems
US7136271B2 (en) * 2003-03-17 2006-11-14 Illinois Tool Works Inc Static charge neutralizing assembly for use on rollers and shafts
DE10315603A1 (en) * 2003-04-05 2004-10-14 Zf Lenksysteme Gmbh steering gear
JP2006044479A (en) * 2004-08-05 2006-02-16 Toyota Motor Corp Steering device

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2007066095A1 *

Also Published As

Publication number Publication date
GB0524837D0 (en) 2006-01-11
WO2007066095A1 (en) 2007-06-14

Similar Documents

Publication Publication Date Title
US11597430B2 (en) Electric drive device and electric power steering device
US20200156696A1 (en) Electric drive device and electric power steering device
US5810111A (en) Electric power steering device
US8243454B2 (en) Electronic control unit
KR102066361B1 (en) Electric drive and electric power steering
US10858037B2 (en) Power steering device
EP2626987B1 (en) Sensing magnet apparatus for motor
JP5067159B2 (en) Electric power steering device
USRE50061E1 (en) Electric drive device and electric power steering device
EP0963900A3 (en) Electric steering motor with one piece metal shell
US20050178608A1 (en) Power steering device of electric motor type
EP3960583A1 (en) Steer-by-wire steering system having an off-axis steering system support column
DE102009004838A1 (en) Electric motor device for electric power steering and electric device
KR20170097219A (en) Electric Driving Device and Electric Power Steering Device
US10965181B2 (en) Electric drive device and electric power steering device
KR20170096204A (en) Electric Driving Device and Electric Power Steering Device
US20210226507A1 (en) Electric drive device and electric power steering device
DE112017004798T5 (en) ELECTRIC DRIVING DEVICE AND ELECTRIC POWER STEERING DEVICE
US12139208B2 (en) Electrically-operated drive device and electrically-operated power steering device
US12319364B2 (en) Steer-by-wire steering apparatus
EP3890169A1 (en) Electric driving device
US20210265899A1 (en) Electrical drive device and electrical power steering device
EP3516758B1 (en) Housing for an electric machine with a cooling device
DE112017004425T5 (en) ELECTRIC DRIVING DEVICE AND ELECTRIC POWER STEERING DEVICE
US20160304118A1 (en) Driving device

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20080603

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE FR GB IT

17Q First examination report despatched

Effective date: 20081010

DAX Request for extension of the european patent (deleted)
RBV Designated contracting states (corrected)

Designated state(s): DE FR GB IT

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20090721