JP2005199823A - Electric power steering device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently restrict quick change of vehicle behavior without using a vehicle behavior detecting sensor of complicated control logic and high precision to control an electric actuation motor 27. <P>SOLUTION: This electric power steering device for a vehicle is provided with a steering shaft 11, an actuation shaft 21 connected to steered wheels 5 at both end parts and having a rack part 25, the electric actuation motor 27 to move the actuation shaft 21 in the car width direction based on steering information of a steering wheel 3, an extraction shaft 41 having a pinion part 43 engaged with the rack part 25 to extract reverse torque from the steered wheels 5 by kickback, a lower gear mechanism 45 interlocked with the extraction shaft 41, an upper gear mechanism 53 interlocked with the steering shaft 11, and a connection cable 61 to interlock the lower gear mechanism 45 to the upper gear mechanism 53. The lower gear mechanism 45 is composed to have low transmission efficiency from the steered wheel 5 to absorb the reverse torque. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicular electric power steering apparatus used in a vehicle.

  The electric power steering device for a vehicle is a device that steers a pair of steered wheels by steering a steering wheel. The configuration of the conventional electric power steering device for a vehicle is as follows.

  That is, a steering column is provided inside an instrument panel of the vehicle, and a steering shaft that rotates by steering of the steering wheel is provided in the steering column via a bearing. An electric load motor that applies a load in the direction opposite to the steering direction to the steering wheel is disposed in the vicinity of the steering column.

  An operation shaft extending in the vehicle width direction (in other words, the left-right direction) is disposed below the steering wheel, and this operation shaft applies a steering force to the steered wheels by movement in the vehicle width direction. The both ends of the operating shaft are connected to the knuckle arms of the steered wheels via tie rods, respectively. An electric operation motor for moving the operation shaft in the vehicle width direction based on the steering information of the steering wheel is provided below the steering wheel.

  Therefore, when the steering wheel is steered in the clockwise direction (or counterclockwise direction) while applying a load in the direction opposite to the steering direction to the steering wheel by the electric load motor, the steering wheel is driven by the electric operation motor. The operating shaft is moved rightward (or leftward) based on the steering information. Thereby, a steering force can be given to a pair of said steered wheels by the said operating shaft, and it can steer to the left direction (or right direction).

In addition, there exists a thing shown to patent document 1 as a prior art relevant to this invention.
JP 2000-33879 A

  By the way, when the steered wheel receives a kickback, for example, when the vehicle travels on a narrow road or rides on a curb, a reverse torque due to the kickback is input from the steered wheel to the electric power steering device for a vehicle. As a result, vehicle behavior such as yaw rate and lateral acceleration changes, and vehicle travel becomes unstable. Therefore, it is necessary to detect the vehicle behavior by the vehicle behavior detection sensor and to control the electric operation motor so as to suppress the change in the vehicle behavior based on the vehicle behavior information.

  On the other hand, in order to sufficiently suppress a sudden change in vehicle behavior, a complicated control logic for controlling the electric operation motor and a highly accurate vehicle behavior detection sensor are required. There is a problem that the configuration of the apparatus becomes complicated and the production cost of the electric power steering apparatus for a vehicle increases.

In the first aspect of the invention, in the electric power steering apparatus for a vehicle that steers a pair of steered wheels by steering the steering wheel,
A steering shaft that rotates by steering the steering wheel;
Load applying means for applying a load in a direction opposite to the steering direction to the steering wheel;
An operating shaft having both ends connected to the steered wheels, extending in the vehicle width direction (left-right direction), having a rack portion, and applying a steering force to the pair of steered wheels by movement in the vehicle width direction; ;
An electrically operated motor that moves the operating shaft in the vehicle width direction based on steering information of the steering wheel;
An extraction shaft that intersects the axial direction of the operating shaft and has a pinion portion meshed with the rack portion, and that extracts reverse torque from the steered wheels by kickback;
A lower gear mechanism disposed in the vicinity of the operating shaft, interlocked with the extraction shaft, and comprising a plurality of lower gears;
An upper gear mechanism disposed in the vicinity of the steering wheel and linked to the steering shaft, the upper gear mechanism comprising a plurality of upper gears;
A connecting cable for interlockingly connecting the lower gear mechanism and the upper gear mechanism;
At least one of the lower gear mechanism and the upper gear mechanism has a low transmission efficiency from the steered wheel side so as to absorb the reverse torque.

  According to the invention specific matter described in claim 1, the steering wheel is steered in the clockwise direction (or counterclockwise direction) while applying a load in the direction opposite to the steering direction to the steering wheel by the load applying means. Then, the operating shaft is moved leftward (or rightward) by the electric operating motor based on the steering information of the steering wheel. Thereby, a steering force can be given to a pair of said steered wheels by the said operating shaft, and it can steer rightward (or leftward). (General operation of the electric power steering apparatus for a vehicle).

  Here, the steering torque of the steering wheel tends to be transmitted to the lower gear mechanism. However, since the extraction shaft is rotated by the electric operation motor, the rotation torque of the extraction shaft is ahead of the steering torque. Is transmitted to the lower gear mechanism and is not affected by the transmission of the steering torque to the lower gear mechanism.

  In addition to the general operation of the electric power steering device for a vehicle, when the steered wheel receives a kickback, such as when the vehicle travels on a rutted road or rides on a curb, the kickback is performed by the extraction shaft. The reverse rotation torque from the steered wheel is extracted. The reverse torque is transmitted from the extraction shaft to the lower gear mechanism, and further to the connection cable and the upper gear mechanism.

  On the other hand, since any one of the gear mechanisms is configured to have a low transmission efficiency from the steered wheels so as to absorb the reverse torque, when the reverse torque is transmitted to any of the gear mechanisms, The reverse torque is absorbed by any one of the gear mechanisms.

  Thereby, without controlling the electric motor so as to suppress the change of the vehicle behavior based on the vehicle behavior information, in other words, a complicated control logic for controlling the electric motor and high-precision vehicle behavior detection. Without using a sensor, it is possible to sufficiently suppress a sudden change in vehicle behavior and keep the vehicle running stably.

  In the invention according to claim 2, in addition to the invention specific matter according to claim 1, the plurality of upper gears include an upper worm gear integrally provided coaxially with the steering shaft, The upper worm wheel meshes with the upper worm gear and is connected to a part of the connecting cable.

  According to the invention specific matter of claim 2, in addition to the action of the invention specific matter of claim 1, the transmission efficiency from the upper worm wheel to the upper worm gear (transmission efficiency from the steered wheel side) is Since it is extremely low, most of the reverse torque can be absorbed by the upper gear mechanism.

  In the invention according to claim 3, in addition to the invention specific matter according to claim 1, the plurality of lower gears include a lower worm gear coaxially and integrally provided on the extraction shaft, The lower worm wheel meshes with the lower worm gear and is connected to a part of the connecting cable.

  According to the invention specific matter of the third aspect, in addition to the operation similar to the operation by the invention specific matter of the second aspect, the transmission efficiency from the lower worm gear to the upper worm wheel (in other words, the rotation Since the transmission efficiency from the steering wheel side is low, a part of the reverse torque can be absorbed by the lower gear mechanism, and almost the reverse torque can be absorbed by the upper gear mechanism and the lower gear mechanism. .

  According to the first aspect of the present invention, without using the complicated control logic for controlling the electric operation motor and the highly accurate vehicle behavior detection sensor, a sudden change in the vehicle behavior can be sufficiently suppressed, Since the running of the vehicle can be kept stable, the configuration of the vehicle electric power steering device can be simplified, and the production cost of the vehicle electric power steering device can be reduced.

  According to the second aspect of the present invention, in addition to the effect of the first aspect of the invention, the upper gear mechanism can absorb most of the reverse torque, so that a drastic change in vehicle behavior can be sufficiently achieved. It is possible to reliably suppress and improve the running stability of the vehicle.

  According to the third aspect of the present invention, in addition to the effect of the second aspect of the invention, the upper gear mechanism and the lower gear mechanism can absorb substantially all of the reverse torque, so that the vehicle behavior is abrupt. The change can be more sufficiently and reliably suppressed, and the running stability of the vehicle can be further improved.

  The best mode of the present invention will be described with reference to FIG. 1, FIG. 2, and FIG.

  FIG. 1 is a perspective view of a vehicular electric power steering apparatus according to the best mode of the present invention, and FIG. 2 is a view showing a main part of the vehicular electric power steering apparatus according to the best mode of the present invention. FIG. 3 is a control block diagram according to the best mode of the present invention. Note that “left and right” refers to the left and right in FIGS. 1 and 2, and “up and down” refers to the top and bottom in FIGS. 1 and 2.

  As shown in FIGS. 1 and 2, the electric power steering device 1 for a vehicle according to the best mode of the present invention is a device that steers a pair of steered wheels 5 by steering a steering wheel 3. The details of the configuration of the vehicle electric power steering apparatus 1 are as follows.

  A steering column 7 is provided on an instrument panel (not shown) of the vehicle, and an upper casing 9 is provided on the steering column 7. Further, a steering shaft 11 that rotates by steering of the steering wheel 3 is provided in the steering column 7 via a bearing (not shown), and the distal end side of the steering shaft 11 extends into the upper casing 9. It extends.

  An electric load motor 13 that applies a load in the direction opposite to the steering direction to the steering wheel 3 is provided on a side portion of the upper casing 9. A transmission worm gear 15 is integrally provided on the output shaft 13 a of the electric load motor 13, and a transmission worm wheel 17 meshed with the transmission worm gear 15 is integrally provided on the steering shaft 11.

  A cylindrical housing 19 is disposed below the steering wheel 3, and an operating shaft 21 extending in the vehicle width direction (in other words, the left-right direction) is provided in the housing 19. Both end portions of the operating shaft 21 protrude from the housing 19. Here, the operating shaft 21 gives a steered force to the steered wheels by movement in the vehicle width direction, and both ends of the actuated shaft 21 are connected to the knuckle arms of the steered wheels 5 via tie rods 23, respectively. It is. Further, the operating shaft 21 has a rack portion 25 extending in the vehicle width direction.

  An annular electric operation motor 27 that moves the operation shaft 21 in the vehicle width direction is provided in the housing 19. A nut member 29 integrally connected to the annular rotor 27a of the electric operating motor 27 is provided in the housing 19 so as to be rotatable through a bearing (not shown). A thread groove 31 into which the nut member 29 is screwed is formed.

  The electric load motor 13 and the electric operation motor 27 are controlled by the following configuration.

  That is, a steering information detection sensor 33 that detects steering information from the rotational operation of the steering shaft 11 is provided between the steering wheel and the transmission worm wheel in the steering column 7, and the operation shaft 21 is provided in the housing 19. A steering information detection sensor 35 for detecting the steering information from the moving operation is provided. Here, the steering information includes the steering angular velocity, the steering torque, and the like of the steering wheel 3, and the steering information includes the steering angular velocity, the steering torque, and the like of the steered wheels 5.

  The vehicle electric power steering apparatus 1 includes a controller 37 as shown in FIG. 3, and the electric load motor 13, the electric operation motor 27, the steering information detection sensor 33, and the turning information detection sensor 35 include a controller. 37 is electrically connected. Here, the controller 37 calculates the target load information and the target operation information based on the steering information and the turning information, outputs the target load information to the electric load motor 13, and outputs the target operation information to the electric operation motor 27. Output.

  Next, the main part of the best mode of the present invention will be described.

  A lower casing 39 is provided in the vicinity of the operating shaft, and an extraction shaft 41 that intersects the axial direction of the operating shaft 21 is provided in the lower casing 39. Here, the extraction shaft 41 extracts reverse rotation torque from the steered wheels 5 due to kickback, and has a pinion portion 43 that meshes with the rack portion 25.

  Further, the lower casing 39 is provided with a lower gear mechanism 45 that is interlocked with the operating shaft 21. The lower gear mechanism 45 includes a lower worm gear 47 that is integrally provided coaxially with the extraction shaft 41, and a lower worm wheel 49 that is rotatably provided on the lower casing 39 and meshes with the lower worm gear 47. Yes. The lower worm wheel 49 is integrally provided with a lower pulley 51 coaxially.

  Similarly, the upper casing 9 is provided with an upper gear mechanism 53 linked to the steering shaft 11. The upper gear mechanism 53 includes an upper worm gear 55 provided integrally with the steering shaft 11 coaxially and an upper worm wheel 57 provided rotatably on the upper casing 9 and meshed with the upper worm gear 55. Yes. The upper worm wheel 57 is integrally provided with an upper pulley 59 coaxially.

  Furthermore, the lower pulley 51 is connected so that one end side portions of a pair of connecting cables 61 that interlockly connect the lower gear mechanism 45 and the upper gear mechanism 53 are wound. The other end portion of the connection cable 61 is connected so as to be wound.

  Here, the lower gear mechanism 45 is configured to have low transmission efficiency from the lower worm gear 47 to the lower worm wheel 49 (in other words, transmission efficiency from the steered wheel 5 side) so that a part of the reverse torque can be absorbed. It is. Further, the upper gear mechanism 53 is configured to have a very low transmission efficiency from the upper worm wheel 57 to the upper worm gear 55 (in other words, transmission efficiency from the steered wheel 5 side) so that most of the reverse torque can be absorbed. ing.

  Next, the operation of the best mode of the present invention will be described.

  When the steering wheel 3 is steered clockwise (or counterclockwise) while applying a load in the direction opposite to the steering direction to the steering wheel 3 by the electric load motor 13, the steering wheel 3 is steered by the electric operation motor 27. Based on the information, the operating shaft 21 is moved leftward (or rightward). Thereby, a steering force can be given to the pair of steered wheels 5 by the operating shaft 21 and the steered wheels 5 can be steered rightward (or leftward) (general operation of the electric power steering device 1 for a vehicle).

  Here, the steering torque of the steering wheel 3 tends to be transmitted to the lower gear mechanism 45. However, since the extraction shaft 41 is rotated by the electric operation motor 27, the rotation torque of the extraction shaft 41 is ahead of the steering torque. Is transmitted to the lower gear mechanism 45 and is not affected by the transmission of the steering torque to the lower gear mechanism 45.

  In addition to the general operation of the electric power steering device 1 for a vehicle, when the steered wheel 5 receives a kickback, for example, when the vehicle travels on a rutted road or rides on a curb, the extraction shaft 41 kicks it back. The reverse torque from the steered wheel 5 is extracted. The reverse torque is transmitted from the extraction shaft 41 to the lower gear mechanism 39, the pair of connecting cables 61, and the upper gear mechanism 53.

  On the other hand, the lower gear mechanism 39 can absorb part of the reverse torque, and the upper gear mechanism 53 can absorb most of the reverse torque, in other words, the lower gear mechanism 39 and the upper gear mechanism. 53 can absorb almost all the reverse torque.

  Accordingly, the electric operation motor 27 is not controlled so as to suppress the change of the vehicle behavior based on the vehicle behavior information, in other words, the complicated control logic for controlling the electric operation motor 27 and the highly accurate vehicle behavior detection. Without using a sensor, it is possible to sufficiently suppress a sudden change in vehicle behavior and keep the vehicle running stably.

  As described above, according to the best mode of the present invention, sudden changes in vehicle behavior can be sufficiently suppressed without using complicated control logic for controlling the electrically operated motor 27 and the highly accurate vehicle behavior detection sensor. As a result, it is possible to keep the vehicle running stably, thereby simplifying the configuration of the vehicular electric power steering device 1 and reducing the production cost of the vehicular electric power steering device 1.

  In addition, since the reverse torque can be almost completely absorbed by the upper gear mechanism 53 and the lower gear mechanism 45, a sudden change in the vehicle behavior can be more sufficiently and reliably suppressed to further improve the running stability of the vehicle. it can.

  Further, when a large steering wheel steering force is required due to a failure of the electric operation motor 27, etc., the electric load motor 13 that normally applied a load in the direction opposite to the steering direction is given assistance in the steering direction. By using it as a means, it is possible to reduce the load on the steering wheel.

  The present invention is not limited to the description of the best mode of the invention described above, and can be implemented in various other modes by making appropriate modifications.

1 is a perspective view of an electric power steering device for a vehicle according to the best mode of the present invention. It is a figure which shows the principal part of the electric power steering device for vehicles concerning the best form of this invention. It is a control block diagram concerning the best mode of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus for vehicles 3 ... Steering wheel 5 ... Steering wheel 11 ... Steering shaft 13 ... Electric load motor 21 ... Operation shaft 25 ... Rack part 27 ... Electric operation motor 31 ... Operation shaft 33 ... Steering information detection sensor 35 ... Steering information detection sensor 37 ... Controller 39 ... Lower gear mechanism 47 ... Lower worm gear 49 ... Lower worm wheel 53 ... Upper gear mechanism 55 ... Upper worm gear 57 ... Upper worm wheel 59 ... Upper pulley 61 ... Connecting cable

Claims (3)

In the vehicle electric power steering device (1) for steering the pair of steered wheels (5) by steering the steering wheel (3),
A steering shaft (11) rotated by steering of the steering wheel (3);
Load applying means (13) for applying a load in the direction opposite to the steering direction to the steering wheel (3);
Both ends are respectively connected to the steered wheels (5), extend in the vehicle width direction, have a rack portion (25), and are steered to the pair of steered wheels (5) by movement in the vehicle width direction. An actuating shaft (21) providing
An electrically operated motor (27) for moving the operating shaft (21) in the vehicle width direction based on steering information of the steering wheel (3);
It has a pinion part (43) that intersects the axial direction of the operating shaft (21) and meshes with the rack part (25), and extracts reverse torque from the steered wheels (5) due to kickback. An extraction shaft (41);
A lower gear mechanism (45) disposed in the vicinity of the operating shaft (21) and linked to the extraction shaft (41), and comprising a plurality of lower gears (47, 49);
An upper gear mechanism (53) disposed in the vicinity of the steering wheel (3) and linked to the steering shaft (11), and comprising a plurality of upper gears (55, 57);
A connecting cable (61) for interlockingly connecting the lower gear mechanism (45) and the upper gear mechanism (53);
At least one of the lower gear mechanism (45) and the upper gear mechanism (53) has a low transmission efficiency from the steered wheel (5) side so as to absorb the reverse torque. An electric power steering device for vehicles. The plurality of upper gears (55, 57) mesh with the upper worm gear (55) integrally provided on the steering shaft and coaxially with the upper worm gear (55), and are connected to one of the connecting cables (61). The electric power steering device for a vehicle according to claim 1, comprising an upper worm wheel (57) to which a portion is connected. The plurality of lower gears (45, 47) mesh with the lower worm gear (47) coaxially provided integrally with the extraction shaft (41) and the lower worm gear (47), and the connecting cable (61 And a lower worm wheel (47) to which a part of the electric power steering device is connected.

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