WO2015146803A1

WO2015146803A1 - Driving mode switch control method and vehicle

Info

Publication number: WO2015146803A1
Application number: PCT/JP2015/058332
Authority: WO
Inventors: 石河　智海
Original assignee: Ntn株式会社
Priority date: 2014-03-25
Filing date: 2015-03-19
Publication date: 2015-10-01
Also published as: JP2015182637A; JP6382544B2

Abstract

The invention addresses the issue of safely and surely switching a driving mode when a vehicle is stopped on a slope. First, a driver operates a mode switching means (42) provided nearby a driver's seat (S1). Next, the incline angle is measured by an incline angle measurement means (71) (S2). Further, an ECU (70) determines whether or not the measured incline angle is equal to or greater than a prescribed angle (equal to or greater than 5 degrees, for example) predetermined for each incline direction (S3). If the incline angle is equal to or greater than the prescribed angle, the operation of the mode switching means (42) performed by the driver is cancelled (S4). Conversely, if the incline angle is less than the prescribed angle, the driving mode is switched on the basis of the operation of the mode switching means (S5).

Description

Travel mode switching control method and vehicle

The present invention employs a switching control method for a traveling mode of a vehicle including an in-wheel motor that can switch the traveling mode between a normal traveling mode and a special traveling mode such as in-situ rotation, and the switching control method thereof. Regarding vehicles.

Ackerman-Jantou type is used to steer the wheels using a steering link mechanism that connects the left and right wheels (hereinafter collectively referred to as "wheels" including tires, wheels, hubs, in-wheel motors, etc.) There is a steering mechanism called. This steering mechanism uses a tie rod and a knuckle arm so that the left and right wheels have the same center of rotation when the vehicle rotates.

As this steering mechanism, for example, there is a configuration shown in Patent Document 1 below. This steering mechanism is provided with a steering link mechanism for left and right wheels using tie rods and knuckle arms on at least one of the front wheel side and rear wheel side, and the tie rod length, the distance between the left and right tie rods, or the angle between each wheel and the knuckle arm. By providing an actuator that changes any one of them, normal traveling, parallel movement, and all the small travelings can be smoothly performed, and the responsiveness is enhanced.

The steering mechanism shown in the following Patent Document 2 is disposed between the left and right wheels of the front and rear wheels, and can rotate around the axis, and the rotation of the divided steering shaft between the left and right divided steering shafts. Forward / reverse switching means for switching the direction between forward and reverse directions is provided. This switching means enables a steering angle of 90 degrees, lateral movement, and the like.

Patent Document 3 below discloses a technology of a four-wheel steered vehicle in which an actuator is operated in accordance with the steering of the front wheels to steer the rear wheels. Patent Document 4 below discloses a technique of a steering mechanism in which a toe adjustment of the left and right wheels is performed by moving a rack housing connecting the left and right wheels in the front-rear direction to improve running stability.

According to a general Ackermann-Jantou type steering link mechanism, during normal driving, lines extending vertically from the rotation line of each wheel (the center line in the width direction of the wheel) gather in the center of rotation of the vehicle. Smooth running is possible. However, when the lateral movement of the vehicle (transverse movement in the lateral direction with the vehicle facing in the front-rear direction) is obtained, steering the wheel in a direction of 90 degrees with respect to the front-rear direction is a problem with the length of the steering link. It is difficult to interfere with other members. Further, even if one of the left and right wheels is steered at 90 degrees, the other wheel is not completely parallel to the one wheel, and smooth running is difficult.

Also, in this type of vehicle, the front wheels, which are the main steered wheels, are usually steered in a predetermined traveling direction of the vehicle, and the rear wheels, which are the follower steered wheels, are designed to be parallel to the longitudinal direction of the vehicle. Has been. For this reason, when the front wheel of this vehicle is steered and rotated, the rotation center of the front wheel and the rear wheel is not at the same position. For this reason, at low vehicle speeds, the vehicle rotates in a posture in which the rear wheels enter the inside of the rotation circle due to the inner wheel difference, and at high vehicle speeds, the vehicles rotate in a posture in which the front wheels enter the inside of the rotation circle by centrifugal force. That is, there is a problem that even if the front wheels are steered in the rotational direction which is the traveling direction of the vehicle, the vehicle cannot be steered with the posture of the vehicle coincident with the rotational direction. Thus, there is a vehicle having a four-wheel steering mechanism (four-wheel steering device) that improves not only the front wheels but also the rear wheels to improve traveling performance.

As a vehicle having a four-wheel steering mechanism (a so-called 4WS vehicle), for example, the technique described in Patent Document 1 allows the vehicle to move in the lateral direction, turn around, and the like. However, in order to change the length of the tie rod, the distance between the left and right tie rods, or the angle between the wheel and the knuckle arm, many actuators are provided, and complicated control of each actuator is required. Further, the technique described in Patent Document 2 has a complicated structure due to its mechanism, and uses a large number of gears to steer the wheels by the rotation of the rack bar. For this reason, rattling is likely to occur between the gears, and it is difficult to smoothly steer the wheels.

Further, the technique of Patent Document 3 is an example of a conventional four-wheel steering mechanism and enables rear wheel steering, but it is difficult to move in the lateral direction only with this mechanism. Furthermore, the technique of Patent Document 4 has a problem that it can not adjust to a lateral movement or a small turn of the vehicle while toe adjustment is possible.

In order to solve the problems of the steering mechanism described in Patent Documents 1 to 4, the inventor of the present application has proposed a steering mechanism shown in Patent Document 5 below. This steering mechanism has two rack bars that can move independently on the left and right sides, and each of the rack bars is connected to one of the left and right wheels via a tie rod, and is driven by a synchronous gear held in a synchronous gear box. The rack bar is movable opposite to the synchronous gearbox. The two rack bars are each provided with a pinion gear that meshes with the rack bar, and a coupling mechanism is provided between the two pinion gears so that the rotation shafts of both the pinion gears can be coupled or separated. When this coupling mechanism is coupled, both rack bars can be moved together in the same direction by the same distance, that is, the left and right wheels can be steered in the same direction. On the other hand, when this coupling mechanism is separated, both rack bars can be moved in the opposite direction by the same distance, that is, the left and right wheels can be steered in the opposite direction.

This steering mechanism can realize special travel modes such as lateral movement and small turn with a simple configuration. For example, when changing from normal driving mode to in-situ rotation and lateral movement modes, the front ends of the left and right front wheels and the rear ends of the left and right rear wheels approach each other. To steer.

As shown in FIG. 5, as a vehicle equipped with this steering mechanism, in order to improve the running / steering characteristics of the vehicle, a contact point P ′ between the extension line of the kingpin axis P (steering rotation axis) and the ground surface, Some have a suspension device designed so that the ground contact center T ′ of the tire T does not coincide (the scrub radius S ≠ 0). In a vehicle equipped with this suspension device, switching between the normal travel mode and special travel modes such as in-situ rotation and lateral travel is performed by turning the wheel around the kingpin. As a method of this steering, a method of relatively moving the rack bar by a rack bar operating means using a rotating operation of the steering or an actuator that operates in conjunction with the rotating operation or the like (see paragraphs 0017 and 0018 of Patent Document 5) ), A method of generating a driving force in the in-wheel motor and rotating the tire (see paragraph 0025 of Patent Document 5) may be employed.

In a vehicle equipped with the steering mechanism described in Patent Document 5, when switching the travel mode, either a steering method using a steering rotation operation or a steering method using a driving force of an in-wheel motor is used. Also in the rudder method, it is necessary to rotate the wheel to some extent. In other words, the wheels cannot be braked when the travel mode is switched. For example, when switching the travel mode while the vehicle is stopped on an inclined ground, it is necessary to release the brake once and the travel mode is being switched (particularly in the initial stage of switching the travel mode from the normal travel mode to the special travel mode). In addition, the vehicle may move carelessly along its inclination due to its own weight. For this reason, there has been a demand for the development of a steering mechanism capable of switching the driving mode safely and reliably for a vehicle including a suspension device designed so that the scrub radius S ≠ 0.

Therefore, as described in Patent Document 6 below, the inventor prevents the rotation of the rear wheels when turning the front wheels and switches the rear wheels while switching the traveling mode of the vehicle. Has further invented a configuration that prevents rotation of the front wheels and prevents the vehicle from inadvertently moving along its inclination with its own weight when switching the running mode. According to this configuration, the driving mode of the vehicle can be switched safely and reliably.

Japanese Patent Laid-Open No. 04-262971 Japanese Patent No. 4635754 Utility Model Registration No. 2600374 JP 2003-127876 A Japanese Patent Application No. 2013-158876 (unpublished) Japanese Patent Application No. 2014-26582 (unpublished)

When the vehicle is stopped on a sloping ground, a larger load is applied to the lower wheel (lower slope) of the vehicle than the higher wheel (lower slope). For example, as shown in FIG. 1, when the vehicle is stopped on an inclined ground where the front of the vehicle is inclined upward, a larger load is applied to the rear wheels than to the front wheels. If the rear wheels are to be steered in this state, a large load is applied to the axle and the suspension, and there is a possibility that a malfunction may occur in the vehicle parts such as the steering device and the undercarriage.

Therefore, an object of the present invention is to prevent a large load from being applied to vehicle parts such as a steering device when a vehicle stopped on an inclined ground is steered.

In order to solve this problem, in the present invention, a step of operating the mode switching means to steer at least one of the left and right front wheels or the rear wheel in a predetermined direction, and an inclination angle measuring means mounted on the vehicle body Canceling the operation or rejecting the operation when the obtained measurement result of the inclination angle of the vehicle body is equal to or greater than a predetermined angle; and the measurement result is less than the predetermined angle. When it is small, the vehicle has a step of turning in accordance with the above operation, and a traveling mode switching control method for a vehicle is configured.

In this way, since the turning operation is not performed in a state where the inclination angle exceeds a predetermined angle and a large load is applied to some of the wheels, it is possible to prevent the malfunction of the vehicle parts caused by the turning. it can.

In the above configuration, all the wheels are steered, and the predetermined direction is a left-right reverse direction for the left and right front wheels, a left-right reverse direction for the left and right rear wheels, and a left-right reverse direction for the left and right front wheels. It can be.

Such wheel behavior occurs when changing from the normal travel mode to a special travel mode such as the spot rotation mode or the lateral movement mode. When steering to these special modes, a large load is often applied to vehicle components such as a steering device and a suspension. By applying the above travel mode switching control method to the special travel mode, the effect of preventing the malfunction of the vehicle parts is further enhanced.

In each of the above-described configurations, the vehicle inclination direction is calculated from the measurement results of the vehicle body front-rear direction and left-right inclination angles obtained by the inclination angle measurement means, and the measurement results are obtained for each inclination direction. When the angle is equal to or greater than the predetermined angle, a step of canceling the operation or rejecting the operation can be applied.

For example, when the vehicle is tilted in the left-right direction in addition to the front-rear direction, a large load is applied to one of the lower wheels (lower tilt side) of the front and rear wheels There is. If the steering operation is performed in this state, there is a further possibility that the lower (inclined lower) wheel will have a problem as compared with the case where the vehicle is simply tilted in the front-rear direction. In this way, the predetermined angle predetermined for each inclination direction is compared with the actual inclination angle in the inclination direction so that the steering operation is not performed when the actual inclination angle is equal to or greater than the predetermined angle. By performing the switching control of the travel mode, it is possible to reliably prevent the malfunction of the vehicle parts corresponding to this inclination direction.

Here, the “predetermined angle determined for each inclination direction” means, for example, a state in which the front side of the vehicle is lowered (horizontal state in the left-right direction) is 0 degrees, and a state in which the right side of the vehicle is lowered (front-rear direction) Is 90 degrees, the rear side of the vehicle is low (horizontal in the left-right direction) is 180 degrees, and the left side of the vehicle is low (horizontal in the front-back direction) is 270 degrees. It refers to a predetermined angle predetermined for each angle. The step of this angle can be, for example, 30 degrees, 45 degrees, or can be continuous (stepless).

In each configuration, the predetermined angle can be set to 5 degrees. The angle of 5 degrees is an angle at which the load bias to some of the wheels (front wheels or rear wheels) becomes very significant. Therefore, when the inclination angle becomes 5 degrees or more, it is possible to prevent a major problem of the vehicle parts by controlling to stop the switching of the driving mode.

Alternatively, the predetermined angle can be 3 degrees. The angle of 3 degrees is an angle at which the load bias on some of the wheels starts to increase. Therefore, when the inclination angle becomes 3 degrees or more, the vehicle parts can be prevented from malfunctioning by controlling the switching of the driving mode to be stopped.

This predetermined angle can be changed as appropriate in accordance with the vehicle configuration (vehicle shape, dimensions, weight, etc.). This is because, depending on the configuration of the vehicle, the bias of the load on the front and rear wheels and the left and right wheels during tilting changes.

Further, a mode switching means for switching the driving mode, a steering device capable of turning the left and right front and rear wheels in the same direction in the left and right direction or the reverse direction by operation of the mode switching means, and a vehicle body are mounted. A tilt angle measuring means for measuring, and a control device for determining that the steering is not performed when a measurement result obtained by the tilt angle measuring means is equal to or greater than a predetermined angle for each tilt direction. A vehicle can be configured.

In this way, by measuring the tilt angle of the vehicle by the tilt angle measuring means and determining whether or not the steering is possible based on this tilt angle, as described above, it is possible to prevent problems of vehicle parts such as the steering device. Can do. By using an inclination angle sensor capable of simultaneously measuring the inclination of the vehicle in the front-rear direction and the left-right direction as the inclination angle measuring means, more appropriate control can be performed in accordance with the inclination direction of the vehicle.

Further, in this vehicle, the steering device is connected to the left and right wheels, the tie rods for turning the left and right wheels, the pair of rack bars respectively connected to the tie rods of the left and right wheels, and the pair of rack bars. A synchronous gear that meshes with each other and converts the movement of one rack bar in one direction with respect to the parallel direction of the rack teeth into the other direction of the other rack bar; and a first pinion gear that meshes with the one rack bar A second pinion gear meshing with the other rack bar, and a coupling mechanism for coupling or separating the rotation shafts of the first and second pinion gears, and the pair of rack bars are racks of the respective rack bars. And a rack bar operating means that can be moved in the opposite direction along the parallel direction of the teeth.

By connecting the wheels to the pair of rack bars that can be moved independently from each other via tie rods, the pair of rack bars can be fixed together in normal driving mode to operate without any discomfort from conventional steering operations. By moving the pair of rack bars in different directions, various special driving modes such as small turn, on-site rotation, and lateral movement can be realized. Further, by using a pair of rack bars that can be switched between separation and fixation, a complicated mechanism and control are not required, and the cost can be reduced.

In this invention, the step of operating to steer at least one of the left and right front wheels or the rear wheel in a predetermined direction, and the measurement result of the tilt angle of the vehicle body obtained by the tilt angle measuring means mounted on the vehicle body are provided. A step of canceling the operation or rejecting the operation when the angle is equal to or greater than a predetermined angle, and a step of turning according to the operation when the measurement result is smaller than the predetermined angle. And a traveling mode switching control method of the vehicle having the above.

In this way, by measuring the inclination angle of the vehicle body and preventing the wheel from turning when the inclination angle is equal to or greater than a predetermined angle, it is possible to solve the problem of the vehicle parts accompanying the turning. Therefore, the driving mode of the vehicle can be switched safely and reliably.

Image of vehicle according to the present invention Plan view showing a vehicle according to the present invention The top view which shows the spot rotation mode in the vehicle of FIG. FIG. 2 is a plan view showing a lateral movement (parallel movement) mode in the vehicle of FIG. Sectional view showing the support state of the wheel The perspective view which shows the external appearance of a steering device The detail of the rack bar operation | movement means of a steering device is shown, (a) is a front view of a separation state, (b) is a front view of a coupling state Front view showing the inside of the steering device The inside of a steering device is shown, (a) is a top view in a state where a pair of rack bars are closest, (b) is a plan view in a state where a pair of rack bars is opened The figure which shows an example of the flow of the switching control method of the driving mode which concerns on this invention The figure which shows the other example of the flow of the switching control method of the driving mode which concerns on this invention

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS After describing the overall configuration and travel mode of a vehicle according to the present invention with reference to the drawings, a travel mode switching control method will be described.

(1) About the whole structure of a vehicle The vehicle 1 shown in FIG. 1 is a micro mobility of a two-seater (horizontally two-seater). In the following, the micro mobility will be described as an example, but the present invention is not limited to the micro mobility and can be applied to a normal vehicle. FIG. 2 is a schematic plan view showing a drive system and a control path of the steering mechanism of the vehicle 1.

Steering devices

10 and 20 are connected to front left and right wheels FL and FR and rear left and right wheels RL and RR via

tie rods

12 and 22, respectively. Each wheel w of the vehicle 1 is provided with an in-wheel motor M, and each wheel w can be directly driven to rotate.

Steering devices

10 and 20 are provided on the front and rear wheels, respectively, and the left and right wheels w are moved in the same direction by rotating the steering 2 around the steering shaft 3 axis or driving the

steering devices

10 and 20 by an actuator. Or it can steer in the reverse direction.

The vehicle 1 is provided with an electronic control unit (ECU) 70 that controls the

steering devices

10 and 20. The ECU 70 is connected to an inclination angle measuring means 71 for measuring the inclination angle of the vehicle 1. As the tilt angle measuring means 71, various sensors such as a gyro sensor and an acceleration sensor can be employed. As shown in FIG. 1, when the vehicle 1 is parked in the front-rear direction (the front is highly inclined), a larger load is applied to the rear wheels RL and RR than the front wheels FL and FR. When a wheel is steered in a state where this large load is applied, a large force is applied to vehicle parts such as the

steering devices

10 and 20 connected to the wheel, and there is a possibility that a problem occurs in the vehicle part.

Therefore, as will be described in detail later (see FIGS. 10 and 11), when the inclination angle measuring means 71 detects an inclination greater than a predetermined angle, this is notified to the ECU 70, and the mode switching by the driver is performed. The switching control method is configured so that the operation of the means 42 is canceled or the acceptance of the operation of the mode switching means 42 is rejected. As a result, the driving mode is not switched when the vehicle 1 is inclined at a predetermined angle or more, and the steering is performed while a large load is applied to some of the wheels, causing a problem in the vehicle parts. Can be prevented.

In this embodiment, as the inclination angle measuring means 71, an inclination angle sensor capable of simultaneously measuring the inclination angle of the vehicle 1 in the front-rear direction and the left-right direction is used. Thus, by using the tilt angle sensor, the tilt direction of the vehicle 1 can be calculated from the tilt angles in the front-rear direction and the left-right direction. The predetermined angle predetermined for each inclination direction is compared with the actual inclination angle in the inclination direction measured by the inclination angle measuring means 71, and the driving mode is switched when the actual inclination angle is equal to or larger than the predetermined angle. By performing the control so as not to perform the operation, it is possible to reliably prevent the occurrence of the malfunction of the vehicle parts. In addition, as long as it is only necessary to measure the inclination in the front-rear direction, a sensor that can measure only the inclination in the front-rear direction may be employed.

As long as the traveling mode switching control method according to the present invention can be implemented, any steering device may be used for the vehicle 1 according to the present invention, but in FIGS. 6 to 9 (a) and 9 (b) It is particularly preferable to use the

steering devices

10 and 20 described in detail. Hereinafter, the configuration and operation of the

steering devices

10 and 20 and the behavior of the wheel w in each travel mode will be described in detail for the vehicle 1 employing the

steering devices

10 and 20.

As shown in FIG. 2, the vehicle 1 includes a front wheel steering device 10 and a rear wheel steering device 20, and can steer the four wheels w in desired directions. This steering is performed by driving the steering device 10 for the front wheels by operating the steering 2 or an actuator such as a motor, and driving the steering device 20 for the rear wheels by an actuator such as a motor. In this turning, in addition to the operation of the steering wheel 2 and the operation of the actuator, the tire T is rotated by the driving force of the in-wheel motor M provided on each wheel w to turn the wheel w around the kingpin axis P. It is also possible to assist (see FIG. 5). It is also possible to steer only by the driving force of the in-wheel motor M without operating the steering 2 or the actuator by the driver.

The steering device 20 may be provided only on the rear wheel and the front wheel may be provided with a normal general steering device, or the front wheel and the rear wheel may have different types of steering devices. .

The front and

rear steering devices

10 and 20 are each provided with two rack bars for turning the left and right wheels w. Hereinafter, for both the front wheel and the rear wheel, the rack bar connected to the left wheel w with respect to the longitudinal direction of the vehicle 1 is the first rack bar 53, and the rack bar connected to the right wheel w is the second rack bar 54. Called. The two

rack bars

53 and 54 extend in parallel to each other. Note that the direction indicated by the left-pointing arrow in FIG. 2 is the forward direction of the vehicle. The traveling mode of the vehicle can be changed to a special traveling mode such as an in-situ rotation mode shown in FIG. 3 or a lateral movement mode shown in FIG. This special travel mode will be described in detail later. In addition, the arrow described in each figure has shown the front direction of the vehicle 1 similarly to the arrow described in FIG.

The connecting

members

11 and 21 of the rack bars 53 and 54 are connected to the left and right wheels w of the front wheel or the rear wheel via

tie rods

12 and 22, respectively. Various members such as a knuckle arm are appropriately interposed between the

tie rods

12 and 22 and the wheel w.

FIG. 5 shows a connection state between the wheel w in which the in-wheel motor M is accommodated and the

tie rods

12 and 22. All the wheels w can be steered with the kingpin axis P connecting the center lines of the ball joints BJ provided at the tips of the upper arm UA and the lower arm LA supported by the vehicle frame, respectively. ing. In the in-wheel motor M, the motor unit 101, the speed reducer 102, and the wheel bearing 103 are sequentially arranged in series from the inner side of the vehicle body toward the wheel w. As shown in this figure, when the contact point of the kingpin shaft P (steering rotation shaft) with the ground is P ′ and the ground contact center of the tire T is T ′, the positions of the two do not match (scrub) The tire T can be rotated by the driving force of the in-wheel motor M provided on the wheel w on the condition that the radius S ≠ 0) to assist the steering of the wheel w around the kingpin axis P.

As shown in FIG. 6, the first rack bar 53 and the second rack bar 54 are rack cases (steering cylinders) that extend in the left-right direction with respect to the straight traveling direction (front-rear direction) of the vehicle 1 in each

steering device

10, 20. 50. The rack case 50 is supported by a frame (chassis) (not shown) of the vehicle 1.

The attachment of the rack case 50 to the vehicle 1 can be directly or indirectly screwed to the frame of the vehicle 1 via a plurality of flange portions 50a provided in the rack case 50, for example.

The first rack bar 53 and the second rack bar 54 can move simultaneously within the rack case 50 by the same distance in the same left-right direction with respect to the straight traveling direction of the vehicle 1. This operation is performed by the operation of the normal steering actuator 31 (see FIG. 2) based on the operation of the steering 2 performed by the driver. By this operation, the left and right wheels w can be simultaneously steered in the same direction in the left and right during normal travel.

7 (a) and 7 (b), the pinion shaft 61 is connected to the steering shaft 3 (see FIG. 2) or the actuator 31 (see FIG. 2) such as a motor that is operated by the rotation operation of the steering 2. A first pinion gear 62 is coupled to the pinion shaft 61 so as to be integrally or integrally rotatable, and a second pinion gear 65 is provided coaxially with the first pinion gear 62. The first pinion gear 62 meshes with the first rack bar 53, and the second pinion gear 65 meshes with the second rack bar 54, respectively.

Between the first pinion gear 62 and the second pinion gear 65, there is provided a coupling mechanism 63 that couples or separates both pinion gears 62, 65 in the rotational direction. FIG. 7A shows a separated state, and FIG. 7B shows a joined state.

Steering devices

10 and 20 are each provided with rack bar operation means 60 as shown in FIG. The rack bar operation means 60 opposes the first rack bar 53 and the second rack bar 54 in the left-right direction with respect to the straight traveling direction of the vehicle 1, that is, along the direction in which the rack extends and contracts (the direction in which the rack teeth are arranged in parallel). It has the function of moving simultaneously in the same direction (the opposite direction) by the same distance.

As shown in FIG. 8, the rack bar operating means 60 is a rack gear of the pair of rack bars 53, 54 facing each other, that is, the synchronization rack gear 53a of the first rack bar 53 and the synchronization rack gear 54a of the second rack bar 54. Are provided with first synchronization gears 55 that mesh with each other.

The first synchronization gear 55 includes three

gears

55a, 55b, and 55c that are arranged in parallel at regular intervals along the parallel direction of the rack teeth of the rack bars 53 and 54. Driving force input from the rack bar operating means 60 to the first rack bar 53 while the connection of the first and second pinion gears 62 and 65 by the connection mechanism 63 shown in FIGS. Thus, when the rack teeth are moved in one direction with respect to the parallel direction of the teeth of the rack, the movement is converted into the movement of the second rack bar 54 in the other direction.

As shown in FIG. 8, FIG. 9A and FIG. 9B, a gear 56a constituting a second synchronization gear 56 is provided between the

adjacent gears

55a and 55b of the first synchronization gear 55 and between the

gears

55b and 55c. , 56b are arranged. The second synchronization gear 56 meshes only with the first synchronization gear 55 without meshing with the synchronization rack gear 53 a of the first rack bar 53 or the synchronization rack gear 54 a of the second rack bar 54. The second synchronization gear 56 is for moving the three

gears

55a, 55b, 55c of the first synchronization gear 55 in the same direction by the same angle. By the second synchronization gear 56, the first rack bar 53 and the second rack bar 54 can smoothly move relative to each other.

Further, as shown in FIGS. 7A and 7B, the first rack bar 53 and the second rack bar 54 include steering rack gears 53b and 54b, respectively, separately from the synchronization rack gears 53a and 54a. .

The first rack bar 53 and the second rack bar 54 are obtained by integrally fixing the synchronizing rack gears 53a and 54a and the steering rack gears 53b and 54b, respectively, by fixing means such as a bolt shaft. As good as

The steering rack gears 53b and 54b function as driving force input means for moving the rack bars 53 and 54 along the parallel direction of the rack teeth with respect to the frame of the vehicle 1.

In order to change the travel mode from the state shown in FIG. 9A (straight-ahead state) to the state shown in FIG. 9B (the state of the lateral movement mode described later), the coupling mechanism 63 is separated. After that, the first rack bar 53 is moved in one direction by the input of the driving force from the rack bar operating means 60. Then, the force is transmitted to the second rack bar 54 via the first synchronization gear 55 meshed with both the first rack bar 53 and the second rack bar 54, and the second rack bar 54 receives the first rack bar 54. It moves simultaneously by the same distance in the opposite direction to the one rack bar 53.

In the straight traveling state (see FIG. 9A), the first pinion gear 62 and the second pinion gear 65 are rotationally fixed by the coupling mechanism 63 meshing at the tire (rack bar) position in the straight traveling state. When the steering shaft 2 is rotated by rotating the steering 2, the first rack bar 53 and the second rack bar 54 move simultaneously in the same direction in the left-right direction in the rack case 50 attached to the frame.

Further, in the state of the lateral movement mode (see FIG. 9B), the coupling mechanism 63 is separated, and the first rack bar 53 and the second rack bar 54 mesh with the synchronous gear 55 in the synchronous gear box 66, respectively. ing. The meshing of the synchronization gear 55 causes the rack bars 53 and 54 to move in the opposite direction with respect to the synchronization gear box 66 by the same distance.

Next, the operation of the rack bar operation means 60 will be described.

The rack bar operation means 60 of the front-wheel steering device 10 includes a first rotation shaft (pinion gear shaft) 61 that rotates directly in accordance with the rotation operation of the steering 2 performed by the driver (see FIGS. 7A and 7B). ). Thus, instead of directly rotating the first rotating shaft 61 in accordance with the rotation operation of the steering wheel 2 performed by the driver, the driving of the mode switching actuator 32 that operates in conjunction with the rotation operation of the steering wheel 2 performed by the driver. It is also possible to switch so that rotation is transmitted to the first rotating shaft 61 side by force or by the driving force of the mode switching actuator 32 that operates in conjunction with the operation of the mode switching means 42 provided in the vehicle 1.

The rack bar operation means 60 of the steering device 20 for the rear wheels is also the mode switching means provided in the vehicle 1 by the driving force of the mode switching actuator 32 that operates in conjunction with the rotational operation of the steering 2 performed by the driver. And a first pinion gear 62 that is attached to the first rotation shaft 61 so as to be integrally rotatable with the first rotation shaft 61. Rotation is transmitted from the operating shaft of the mode switching actuator 32 to the first rotating shaft 61 side via the steering shaft 3 (see FIGS. 7A and 7B).

The rack bar operation means 60 includes a first pinion gear 62 integrated with or coupled to the first rotation shaft 61, a second rotation shaft 64 disposed coaxially with the first rotation shaft 61, and the second rotation shaft 64. Is provided with a second pinion gear 65 attached to be integrally rotatable.

FIG. 6 is an external perspective view showing the

entire steering devices

10 and 20. A first rack bar 53 and a second rack bar 54 are accommodated between the front cover 52 and the rear cover 51. Although not shown in the drawings, boots are provided for preventing foreign substances from entering the movable portion from the attachment portions of the

tie rods

12 and 22 to the rack case 50 (the case front portion 51 and the case rear portion 52). The first rotating shaft 61 is connected to the operating shaft of the mode switching actuator 32 via a steering joint (not shown).

As shown in FIGS. 7A and 7B, the first pinion gear 62 meshes with the steering rack gear 53 b of the first rack bar 53, and the second pinion gear 65 is the steering rack gear of the second rack bar 54. 54b.

Between the first pinion gear 62 and the second pinion gear 65, there is provided a coupling mechanism 63 that can be coupled and separated from each other. The coupling mechanism 63 has a function of switching the first rotating shaft 61 and the second rotating shaft 64 between a state in which relative rotation is possible (separated state) and a state in which relative rotation is not possible (coupled state).

7A and 7B, the coupling mechanism 63 includes a fixed portion 63b on the second rotating shaft 64 side and a moving portion 63a on the first rotating shaft 61 side. The moving part 63a is pressed against the fixed part 63b side by an elastic member such as a spring (not shown), and the convex part 63c on the moving part 63a side is coupled to the concave part 63d on the fixed part 63b side of the coupling mechanism 63. The

shafts

61 and 64 are integrally rotatable. Note that the projections 63c may be provided on the fixed portion 63b side, and the recesses 63d may be provided on the moving portion 63a side, with the concave and convex portions being reversed.

By moving the moving part 63a in the axial direction with respect to the fixed part 63b of the connecting mechanism 63 by an external input from a driving source such as a push solenoid (not shown), the connection between the fixed part 63b and the moving part 63a is separated. The first rotating shaft 61 and the second rotating shaft 64 rotate independently. That is, the first pinion gear 62 and the second pinion gear 65 can rotate independently (the separated state). FIG. 7A shows a separated state of the coupling mechanism 63, and FIG. 7B shows a coupled state thereof.

When the first pinion gear 62 and the second pinion gear 65 are capable of relative rotation due to the separation of the coupling mechanism 63, the first pinion gear 62 is engaged with the first rack bar 53, and the second pinion gear 65 is engaged with the second rack. It meshes with the bar 54. Further, the first rack bar 53 and the second rack bar 54 are engaged with each other by a first synchronization gear 55. At this time, when a rotational force is input to the first pinion gear 62, the first rack bar 53 moves in the lateral direction (one direction) along the parallel direction of the teeth of the rack, that is, the left-right direction of the vehicle. When the first rack bar 53 moves in the lateral direction, the first synchronization gear 55 rotates, and the second rack bar 54 moves simultaneously in the opposite direction (the other direction) from the first rack bar 53 by the same distance. At this time, the second pinion gear 65 is freely rotated by the movement of the second rack bar 54.

As described above, the first rackion gear 62 and the second pinion gear 65 can be switched to the coupled state or the separated state by the coupling mechanism 63 so that the pair of rack bars 53 and 54 move integrally in the left-right direction. Thus, it is possible to easily switch between the state of moving separately in the opposite direction.

That is, the coupling mechanism 63 is coupled so that the pair of rack bars 53 and 54 move together in the left-right direction, and the driver operates the steering wheel 2 to move the left and right wheels w to the kingpin axis P (see FIG. 5) can be simultaneously steered around in the same direction. At this time, since the first rack bar 53 and the second rack bar 54 move together, the first synchronization gear 55 does not rotate.

Further, the coupling mechanism 63 is separated so that the pair of rack bars 53 and 54 are separately moved in opposite directions, and the driver operates the steering wheel 2 to move the left and right wheels w to the kingpin shaft P (see FIG. 5)) can be simultaneously steered in the opposite directions, i.e. in opposite directions.

At the time of mode switching, the driving force of the mode switching actuator 32 (see FIG. 2) is input to the respective rack bars 53 and 54 through the rotation of the pinion gears 62 and 65. When the driving force of the mode switching actuator 32 is input to the rack bars 53 and 54 through the rotation of the pinion gear 62, the rotation of the steering shaft 3 may not be transmitted to the steering 2. The transmission may be allowed.

Furthermore, the normal steering actuator 31 can also serve as the mode switching actuator 32. That is, the normal steering actuator 31 may input rotation to the first rotating shaft 61 via the steering shaft 3 at the time of mode switching. Further, the role of the mode switching actuator 32 can be substituted by the driving force of the in-wheel motor M provided on each wheel.

(2) Vehicle Travel Modes Hereinafter, main travel modes of the vehicle 1 described in the item (1) will be described.

(Normal driving mode)
2 is a state in which the first rack bar 53 and the second rack bar 54 of the front wheel steering device 10 can be moved integrally, that is, a state where the coupling mechanism 63 is coupled (see FIG. 7B). ). When the steering 2 is operated in this state, the first rack bar 53 and the second rack bar 54 are integrally moved in the left-right direction within the rack case 50 of the steering device 10.

When the first rack bar 53 of the steering device 10 is moved in the left and right direction by the driving force of the normal steering actuator 31 or the operation of the steering 2, the second rack bar 54 is also integrally moved in the same direction by the same distance. The left and right wheels w of the front wheels are steered by a predetermined angle in the same direction. That is, by completely fixing the two

rack bars

53 and 54 together, it is possible to travel equivalent to a normal vehicle, and depending on the situation such as straight turn, right turn, left turn, etc., by the driver's steering 2 operation. Necessary steering can be performed freely.

(In-situ rotation mode)
The steered state of each wheel in the spot rotation mode is shown in FIG. By separating the coupling mechanism 63 (see FIG. 7A), the first rack bar 53 and the second rack bar 54 can be operated separately. At this time, the driving force is input from the mode switching actuator 32 to the first pinion gear 62, and the first rack bar 53 and the second rack bar 54 move the same distance in opposite directions. That is, if the first synchronization bar 55 is interposed between the first rack bar 53 and the second rack bar 54 and the first rack bar 53 moves in one direction in the left-right direction, the second rack bar 54 Move in the direction.

The first rack bar 53 and the second rack bar 54 are moved in opposite directions to each other, and as shown in FIG. 3, the connecting mechanism 63 is coupled and fixed at a position where the central axes of all four front and rear wheels w are substantially directed to the vehicle center. Let Since the central axes of all four wheels w are substantially directed to the vehicle center, the vehicle center does not move from the place (or almost does not move) by the driving force of the in-wheel motor M provided on each wheel w. ), So-called in-situ rotation is possible.

(Lateral movement mode)
The steered state of each wheel in the lateral movement mode is shown in FIG. Similarly to the in-situ rotation mode, the coupling mechanism 63 is separated (see FIG. 7A), and all four front and rear wheels w are directed in a direction of 90 degrees with respect to the straight traveling direction (left and right direction with respect to the straight traveling direction of the vehicle). As described above, the first rack bar 53 and the second rack bar 54 in the

steering devices

10 and 20 are moved in opposite directions by the rotation input from the mode switching actuator 32 to the first pinion gear 62. Then, the coupling mechanism 63 is coupled at the position where the wheel w becomes 90 degrees (see FIG. 7B), and the pair of rack bars 53 and 54 are fixed.

With the coupling mechanism 63 coupled in this manner, the first rack bar 53 and the second rack bar 54 in the

steering devices

10 and 20 are moved straight by the driving force of the normal steering actuator 31 or the operation of the steering 2. It is possible to finely adjust the direction (tire angle) of the wheel w by moving it in the left-right direction integrally with the direction.

FIG. 4 shows the positional relationship between the pair of rack bars 53 and 54 of the front and rear

wheel steering devices

10 and 20 and the direction of the wheels w in the lateral movement mode. Compared to the in-situ rotation mode, the pair of rack bars 53 and 54 protrude outward, and the connecting portion of the

tie rods

12 and 22 to the wheel w is located on the outermost side in the vehicle width direction. Yes. Even in this lateral movement mode, the direction (tire angle) of the wheel w can be finely adjusted by the driving force of the normal steering actuator 31 or the operation of the steering 2.

Switching between the above modes can be performed by the driver operating the mode switching means 42 provided in the cab.

(3) Travel Mode Switching Control Method As shown in FIG. 1, in the vehicle 1 in a state of stopping on an inclined ground having an inclination angle θ, a normal travel mode and a special travel mode such as in-situ rotation and lateral movement are provided. A flow of the switching control method for switching between the two will be described.

In this switching control method, as shown in an example of the flow in FIG. 10, first, the driver operates the mode switching means 42 provided near the driver's seat (S1). Next, the tilt angle is measured by the tilt angle measuring means 71 (S2). Further, ECU 70 determines whether or not the measured inclination angle is equal to or greater than a predetermined angle (for example, 5 degrees or more) (S3). When the inclination angle is equal to or larger than the predetermined angle (see YES arrow in FIG. 10), the operation of the mode switching means 42 performed by the driver is canceled (S4). Thus, by canceling the mode switching operation, as shown in FIG. 1, the wheels w are steered while a large load is applied to the rear wheels, and the vehicle components such as the steering device 20 for the rear wheels. It is possible to prevent a malfunction from occurring. On the other hand, when the tilt angle is smaller than the predetermined angle (see NO arrow in FIG. 10), the driving mode is switched based on the operation of the mode switching means (S5).

Another example of the flow of this switching control method is shown in FIG. In this flow, first, the tilt angle is measured by the tilt angle measuring means 71 (S6). Next, ECU 70 determines whether or not the measured inclination angle is equal to or greater than a predetermined angle (for example, 5 degrees or more) (S7). When the inclination angle is equal to or larger than the predetermined angle (see the YES arrow in FIG. 11), even if the driver operates the mode switching means, the acceptance of the operation is rejected (S8). In this way, by rejecting the acceptance of the mode switching operation, as shown in FIG. 1, the wheel w is steered while a large load is applied to the rear wheel, and the rear wheel steering device 20 and the like. It is possible to prevent the occurrence of problems in the vehicle parts. On the other hand, when the inclination angle is smaller than the predetermined angle (see NO arrow in FIG. 11), the operation of the mode switching means by the driver is accepted (S9), and the driving mode is switched (S10). ).

10 and 11 can be applied not only when the vehicle 1 is inclined in the front-rear direction but also when the vehicle 1 is inclined in the left-right direction in addition to the front-rear direction. For example, when the vehicle 1 is inclined in the left-right direction in addition to the front-rear direction, a large load is applied to one of the lower wheels (inclined lower side) of the left and right wheels of the front wheel or the rear wheel. There may be. When the steering operation is performed in this state, there is a further possibility that a problem occurs in the wheel w on the lower side (lower tilt side) as compared with the case where the vehicle 1 is simply tilted in the front-rear direction. In this way, the predetermined angle predetermined for each inclination direction is compared with the actual inclination angle in the inclination direction so that the steering operation is not performed when the actual inclination angle is equal to or greater than the predetermined angle. By performing the switching control of the travel mode, it is possible to reliably prevent the malfunction of the vehicle parts corresponding to this inclination direction.

These switching controls are necessary even when the vehicle 1 is not moved by applying a side brake. Although it is possible to prevent the vehicle 1 from inadvertently moving during mode switching due to the weight of the vehicle 1 by applying the side brake, a large load is applied to some of the wheels, which may cause a malfunction of the vehicle parts. is there.

The overall configuration of the vehicle 1, the driving mode, and the mode switching control method for the driving mode are merely examples, and vehicle components such as the

steering devices

10 and 20 are used when the vehicle 1 stopped on the slope is steered. As long as the problem of the present invention of preventing a large load from being applied can be solved, the entire configuration and the procedure of the mode switching control method can be appropriately changed.

DESCRIPTION OF SYMBOLS 1

Vehicle

10, 20

Steering device

12, 22 Tie rod 42 Mode switching means 53, 54 Rack bar 55 Synchronous gear 60 Rack bar operating means 62 First pinion gear 63 Connection mechanism 65 Second pinion gear 70 Control device (electronic control unit (ECU) ))
71 Inclination angle measuring means FL Left front wheel FR Right front wheel RL Left rear wheel RR Right rear wheel w Wheel

Claims

Operating the mode switching means to steer at least one of the left and right front wheels (FL, FR) or the rear wheels (RL, RR) in a predetermined direction;
When the measurement result of the inclination angle of the vehicle body obtained by the inclination angle measuring means (71) mounted on the vehicle body is greater than a predetermined angle, the operation is canceled or the acceptance of the operation is rejected. Steps,
When the measurement result is smaller than the predetermined angle, turning according to the operation,
A control method for switching the travel mode of the vehicle (1) having the following.
All the wheels (w) are steered, and the predetermined direction is the left and right front wheels (FL, FR) and the left and right rear wheels, the left and right rear wheels (RL, RR) are the left and right reverse directions and the left and right front wheels The vehicle travel mode switching control method according to claim 1, wherein each direction is opposite to the left and right directions of (FL, FR).
The inclination direction of the vehicle (1) is calculated from the measurement results of the inclination angle in the front-rear direction and the left-right direction of the vehicle body (1) obtained by the inclination angle measurement means (71). The vehicle travel mode switching control method according to claim 1 or 2, wherein a step of canceling the operation or rejecting the reception of the operation is applied when the angle is equal to or larger than the predetermined angle predetermined for each direction.
The traveling mode switching control method according to any one of claims 1 to 3, wherein the predetermined angle is 5 degrees.
The traveling mode switching control method according to any one of claims 1 to 3, wherein the predetermined angle is 3 degrees.
Mode switching means (42) for switching the running mode;
Steering devices (10, 20) capable of steering left and right front and rear wheels (FL, FR, RL, RR) in the same direction in the left or right direction or in the reverse direction by operation of the mode switching means (42);
An inclination angle measuring means (71) mounted on the vehicle body for measuring the inclination angle of the vehicle body;
A control device (70) for determining that the steering is not performed when the measurement result obtained by the tilt angle measuring means (71) is equal to or greater than a predetermined angle predetermined for each tilt direction;
Vehicle with.
The steering device (10, 20)
Tie rods (12, 22) connected to the left and right wheels (w) and steering the left and right wheels (w);
A pair of rack bars (53, 54) respectively connected to the tie rods (12, 22) of the left and right wheels (w);
The pair of rack bars (53, 54) mesh with each other, and the movement of one rack bar (53) in one direction with respect to the parallel direction of the rack teeth is converted into the movement of the other rack bar (54) in the other direction. A synchronous gear (55) to
A first pinion gear (62) meshing with the one rack bar (53); a second pinion gear (65) meshing with the other rack bar (54); and the first and second pinion gears (62, 65). A connecting mechanism (63) for connecting or separating the rotating shafts (61, 64) of the rack bars (53, 54) to the rack teeth of the rack bars (53, 54). Rack bar operating means (60) capable of moving in the opposite direction along the parallel direction;
The vehicle according to claim 6 provided with.