JPH01301462A - Steering angle sensor mounting constitution in vehicle - Google Patents

Abstract

PURPOSE:To simplify a steering angle sensor and its mounting mechanism and reduce the size of the sensor by engaging a pinion gear placed inside a housing surrounding a steering shaft, with a rack gear and mounting a steering angle sensor which detects the quantity of revolution of the shaft of the pinion, on the shaft. CONSTITUTION:A rack gear 140 is formed in a position between the ball screw means of a rear wheel steering shaft 30 and a centering spring, and engaged with a pinion 142. The pinion 142 is contained in a housing 40 and held inside it with the shaft 144 of the pinion and a steering angle sensor 120, like a potentiometer, detecting the quantity of revolution of the pinion shaft 144 is mounted on the pinion shaft 144.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a steering angle sensor that detects the steering angle of a steering wheel of an automobile, and in particular, a steering angle sensor that detects a steering angle based on the amount of displacement of a steering shaft connecting left and right steering wheels. The present invention relates to a mounting structure for a steering angle sensor that detects a steering angle sensor.

(Prior Art) Automobiles include two-wheel steering (2WS) vehicles that steer the front wheels and four-wheel steering (4WS) vehicles that steer the rear wheels as well as the front wheels.

When steering the front wheels or rear wheels in this manner, there is a demand for detecting the steering angle of the steered wheel, which is the wheel to be steered, using a sensor for various reasons.

For example, Japanese Utility Model Application Publication No. 62-25277 discloses a JW in which an electric motor is linked to a rear wheel steering mechanism, and the driving force of the electric motor is used to steer the rear wheels in response to the front wheel steering 1ζ.
Although an S vehicle is disclosed, in such a type of 4WS vehicle, for example, there is a need to detect the actual steering angle of the rear wheels in order to check whether the rear wheels are being steered toward the target steering angle, and there is a need to detect the actual steering angle of the rear wheels. There is a desire to detect the actual steering angle of the front wheels in order to control the steering of the wheels.

In response to such a demand for detecting the actual steering angle of the steered wheels, conventionally, a stroke type steering angle sensor has been used that detects the movement of the steering shaft that connects the left and right steered wheels without changing the stroke.

Such a stroke type steering angle sensor is based on the same principle as a variable resistor, and includes a resistance member connected to the vehicle body side and a brush member connected to the steering shaft side and capable of stroke displacement while sliding with the resistance member. With the stroke displacement of the steering shaft, the brush member slides against the resistance member and undergoes a stroke displacement, and the amount of stroke displacement of the steering shaft, that is, the steering angle is detected based on the change in resistance value due to the displacement. It is something to do.

(Problems to be Solved by the Invention) However, when using a stroke type steering angle sensor in which the constituent members undergo stroke displacement as described above,
Since the components of the sensor are subject to stroke displacement, the sensor itself becomes large, which requires a large space and makes layout difficult.In addition, when installing the sensor on the steering shaft, the length of the steering shaft must be increased. There is a problem that this reduces the degree of freedom in the geometry of the base chassis, and the sensor is generally installed outside the housing that surrounds the steering shaft. In this case, the problem arises that damage is likely to occur due to flying stones and the like.

In view of the above circumstances, an object of the present invention is to provide an automobile steering angle sensor mounting structure that can improve layout properties, increase the degree of freedom in the geometry of a base chassis, and solve problems caused by external attachment. be.

(Means for Solving the Problems) In order to achieve the above object, the steering angle sensor mounting structure for an automobile according to the present invention includes: forming rack teeth on the steering shaft connecting the left and right steering wheels; A pinion disposed in a housing surrounding the steering shaft is engaged with the steering shaft, and a steering angle sensor for detecting the amount of rotation of the shaft is attached to the shaft of the pinion.

The above-mentioned steering shaft is, for example, a rear wheel steering shaft of a 4WS vehicle, and is provided with a ball screw means for stroke-displacing the steering shaft in the axial direction and a centering spring means for returning the steering shaft to a neutral position for fail-safety. In some cases, the rack teeth may be formed on the steering shaft at a position between the ball screw means and the centering spring means.

The present invention is applicable regardless of whether the vehicle is a 4WS vehicle or a 2WS vehicle, and whether the steered wheels are front wheels or rear wheels.

(Function) According to the above-mentioned mounting structure of the steering angle sensor, the steering angle sensor is attached to the steering shaft via the pinion and pinion shaft, and not only the steering angle sensor itself but also the pinion and pinion shaft do not rotate. Therefore, the steering angle sensor and its mounting mechanism can be simplified and miniaturized, and the mounting mechanism can be easily installed inside the housing, and the steering shaft can be attached to the steering shaft for mounting the steering angle sensor. There is no need to make it long.

Furthermore, for example, in the case of a rear wheel steering shaft of an electric motor-driven 4WS vehicle that is equipped with the above-mentioned centering spring means and ball screw means, if rack teeth are formed between the two means, the above-mentioned It is possible to satisfy the request to arrange both means at the end of the steering shaft, and since the pinion is arranged approximately at the center of the steering shaft, the function of preventing the rotation of the steering shaft around the axis by the ball screw means is Efficiently demonstrated by pinion.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In the embodiment described below, the present invention is applied to the installation of a steering angle sensor that detects the rear wheel steering angle in an electric motor-driven 4WS mechanism that steers the rear wheels in accordance with front wheel steering using an electric motor. .

FIG. 1 is a diagram showing an overall outline of a 4WS mechanism provided with an embodiment of the present invention, and FIG. 2 is a detailed sectional view of the rear wheel steering mechanism portion shown in FIG. 1.

The illustrated 4WS mechanism includes a front wheel steering mechanism 4 that steers left and right front wheels 2L, 2R, and a rear wheel steering mechanism 8 that steers left and right rear wheels 6L, 6R.

The front wheel steering mechanism 4 includes a front wheel steering shaft 14 that extends in the vehicle width direction and has both ends connected to a pair of left and right front wheels 2L and 2H via a pair of left and right tie rods LOL and IOR and knuckle arms 12L and 12R. and a steering shaft 20 having a pinion 16 at one end that meshes with rack teeth (not shown) formed on the steering shaft 14 and a steering wheel 18 at the other end. By operating the steering wheel 18, the front wheel steering shaft 14 is displaced in the vehicle width direction to steer the front wheels 2L and 2R.

The rear wheel steering mechanism 8 includes a rear wheel steering shaft 30 that connects the left and right rear wheels 6L and 6R, an electric servo motor 32, and is rotated by the servo motor 32 to displace the rear wheel steering shaft 30. The rear wheel steering shaft 30 includes a ball screw means 34, a centering spring means 3B that biases the rear wheel steering shaft 30 to return to a neutral position, and a control unit 38 that drives and controls the servo motor 32. The ball screw means 34, centering spring means 36, etc. are housed in a housing 40 fixed to the vehicle body (not shown), as shown in FIG.

The rear wheel steering shaft 30 extends in the vehicle width direction, and has both ends connected to a pair of left and right rear wheels 6L via a pair of left and right tie rods 42L, 42R and knuckle arms 44L, 44R.
6R, and the stroke displacement of the rear wheel steering shaft 30 in the vehicle width direction (axial direction) causes the rear wheel 6L.

6R is steered.

Stroke displacement of the rear wheel steering shaft 30 in the axial direction is performed by the servo motor 32. That is, the servo motor 32 is composed of a step motor, and is driven and controlled by the control unit 38, and the brake 4 is controlled by the control unit 38.
6. Transmit rotation to the ball screw means 34 through a rotation transmission system consisting of the clutch 48 and the reduction gear 50, and steer the rear wheels via the ball screw means 34 against the biasing force of the centering spring means 3B. The shaft 30 is configured to be displaced by a stroke from a neutral position.

The brake 4B locks the rotation transmission system between the servo motor 32 and the rear wheel steering shaft 30 so that the rear wheel steering shaft 30
is maintained at a predetermined displacement state.

That is, during steady steering (when the target steering angle does not change), it is necessary to maintain the rear wheel steering shaft 30 in a predetermined displacement state, but the servo motor 3? This is intended to save power consumption by using this brake 4B instead of the servo lock.

The clutch 48 is connected to the servo motor 3 when a predetermined abnormality occurs.
2 and the rear wheel steering shaft 30 to free the rear wheel steering shaft 30, thereby returning the steering shaft 30 to the neutral position by the centering spring means 36.
The system is set to a WS state to provide a so-called fail-safe.

The brake 46 and clutch 48 are appropriately controlled by the control unit 38.

The brake 46 and clutch latch 48 will be described in detail below with reference to FIG.

The brake 4B includes a disk 52 that is fixed to the output shaft 32a of the servo motor 32, and has a plurality of grooves extending radially on both sides of the disk 52, and the servo motor 32 of the disk 52.
Ring plate 5 having an uneven groove that engages with an uneven groove on the side
4, and a solenoid 58 that attracts the ring plate 54 to a suction plate 56 fixed to the housing 40. When the solenoid 58 is in the OFF state, in which the solenoid 58 is not energized, the ring plate 54 is free together with the disk 52. At the same time, the solenoid 58 is energized.
In this state, the ring plate 54 is attracted to the suction plate 56 while maintaining the meshing state with the disk 52, and the rotation of the disk 52, that is, the output shaft 32a of the servo motor is controlled.
The output shaft 32a is locked by applying braking to the rotation of the output shaft 32a.

The clutch 48 is a twin clutch in which two clutches are provided in series, and the upstream clutch 48A is a normal oven type (disconnection when no current is applied), and the downstream clutch 48B is a normally closed type (connection when no current is applied). has been done. That is, the clutch 48A includes a ring plate 60 having an uneven groove that engages with an uneven groove on the downstream side of the disk 52, and a ring plate 60 that is attached to a disk 64 fixed to a rotating shaft 62 coaxial with the output shaft 32a. When the solenoid 66 is not energized (OFF state), the ring plate 60 and the disc 64 are disconnected, while when the solenoid 66 is energized (ON state), the ring plate 60 and the disc 64 are connected to each other. 64
are connected by surface contact. In addition,
The ring plate 60 maintains a tight meshing state with the disk 52. Further, the clutch 48B is connected to the rotating shaft 62
a ring plate 70 spline-coupled to a hub 68 fixed to the ring plate 7o; a pad 74 that comes into contact with the downstream surface of the ring plate 7o and presses the ring plate 70 upstream by the spring force of the spring 72; bad 74
A drum fixedly attached to a rotating shaft 76 coaxial with the rotating shaft 62 contacts the upstream side surface of the ring plate 70 so as to restrict movement of the ring plate 7° upstream by a predetermined amount or more when pressed by the rotating shaft 62. 78 and a solenoid 80 that sucks the pad 74 from the downstream side and releases the pressure of the ring plate 70 against the drum 78. When the solenoid 80 is in the OFF state, in which electricity is not energized, the ring plate 70 and the drum 78 are flush with each other. In the ON state where the solenoid 70 is connected by contact and is energized, the ring plate 70 and the drum 78 are disconnected from each other.

The rotation of the output shaft 32a caused by the operation of the servo motor 32 is transmitted to the ball screw means 34 only when the brake 46 and clutch 48B are OFF and the clutch 48A is ON, but under normal conditions Rear wheel steering is performed in this state. The clutch 48 is a twin clutch consisting of two clutches 48A and 48B installed in series, so that even if one of the clutches becomes inoperable due to seizure or the like, the other remains in the ON or OFF state. By this, the servo motor 32 and the ball screw means 34
This is to enable the connection with the rear wheel steering shaft 30 to be released, and the reason why one is a normal oven type and the other is a normally closed type is because both clutches 48A, A normal oven type clutch is required to release the above connection when the power supply to 48B is stopped, but using both clutches as a normal oven type means that both clutches must be in the ON state for power transmission during normal times. This is because additional power consumption is required.

As shown in FIG. 2, the ball screw means 34 includes a pole nut 82, a pole screw 84 carved in the steering shaft 30, and a pole 82 interposed between the two pole screws 82 and 84.
6, and the pole nut 82 is connected to the reduction gear 5.
The steering shaft 30 is fixed to a gear 88 that meshes with the gear 88 and rotates integrally with the gear 88, and cannot be displaced in the axial direction of the steering shaft 30. Therefore, when the pole nut 82 is rotated by the servo motor 32, the steering is performed accordingly. The shaft 30 is stroked in the axial direction.

The centering spring means 36, as shown in FIG.
A pair of stoppers 90 and 92 are provided on the steering shaft 30 at a predetermined interval, and both stoppers 9 are loosely fitted on the steering shaft 30.
a pair of spring receivers 94.9 disposed within 0.92 mm and whose movement in the expansion direction is regulated by both stoppers 90.92;
6, a centering spring 98 disposed in a compressed state between both spring receivers 94.98, and a state in which both spring receivers 94.98 are in contact with both stoppers 90.92, similar to the stopper 90.92. In order to restrict the movement of both spring receivers 94.96 in the expansion direction, a housing-side stopper portion 100 and LO2 that come into contact with both spring receivers 94.9 (i) are provided. Steering shaft 30
The housing-side stopper portion 102 on the negative side is formed on a screw cap member 104 screwed onto the housing 40, so that the screwing amount of the stopper 92 and the screw cap member 104 can be adjusted. Thus, the compressive load (preset load) of the centering spring 98 can be appropriately set, and the set preset load always biases the steering shaft 30 toward the neutral position. Note that this preset load needs to be large enough to at least overcome the side force during cornering.

The rear wheel steering by the servo motor 32 is controlled by the control unit 38 as described above.

The rear wheel steering control by the control unit 38 is performed in response to the vehicle speed, and an example of changing the steering ratio (rear wheel steering angle/front wheel steering angle) according to the vehicle speed is as shown in FIG. There are cases. When the control characteristics shown in FIG. 4 are applied, the rear wheel steering angle relative to the front wheel steering angle changes in the same phase direction as the vehicle speed increases, and this situation is shown in FIG.

In order to perform such rear wheel steering control, the control unit 38 receives signals from the steering wheel angle sensor 11O1, the vehicle speed sensor 12, and the rotary encoder 114 that detects the rotational position of the servo motor 32.
The control unit 38 calculates a target rear wheel steering angle based on the steering wheel steering angle (theoretically equal to the front wheel steering angle) and the vehicle speed, and sends a control signal corresponding to the required rear wheel steering angle to the servo motor 32. Output. The rotary encoder 114 constantly monitors whether or not the servo motor 32 is operating properly, that is, the rear wheels 6L and 6R are steered under feedback control.

In the rear wheel steering control described above, the control system has a dual configuration for fail-safe purposes.

That is, a front wheel steering angle sensor 11[1 is added to the steering wheel steering angle sensor 110, a second vehicle speed sensor 11B is added to the vehicle speed sensor 112, and a sensor behind the clutch 48 is added to the rotary encoder 114. Rear wheel steering angle sensor 1 that detects mechanical displacement of a member on the wheel steering shaft 30 side
20 are added, and in these three sets of sensors,
Rear wheel steering is performed only when both corresponding sensors detect the same value. Therefore, above 3
For example, when the vehicle speed detected by the first vehicle speed sensor 112 and the vehicle speed detected by the second vehicle speed sensor 118 are different in the set of sensors, an abnormality (failure) has occurred.
Control during fail mode keeps rear wheels 6L and 6R in the neutral position.

Further, in order to detect various abnormalities, ON/OFF signals from switches 122, 124, 126, and 128 are inputted to the control unit 38, and a signal indicating whether or not power is being generated is inputted from the alternator terminal 130. be done. Here, the switch 122 is a neutral clutch switch, the switch 124 is an inhibitor switch, the switch 12B is a brake switch, and the switch 128 is an engine switch. Note that since these switches are not directly related to the present invention, detailed explanation thereof will be omitted.

Note that 132 in FIG. 2 is a warning lamp that lights up in the fail mode.

Next, the rear wheel steering angle sensor 120 will be described in detail.

As shown in FIG. 2, FIG. 5 which is a sectional view taken along the line V-V in FIG. 2, and FIG. 6 which is a sectional view taken along the line Vt-VT in FIG. It is linked to the rear wheel steering shaft 30 via a pinion mechanism. That is, a rack tooth 140 is formed at a position between the ball screw means 34 and the centering spring means 36 of the rear wheel steering shaft 30, a pinion 142 is meshed with the rack tooth 140, and the pinion 142 is disposed within the housing 4°. The pinion shaft 14 is disposed and supported within the housing 40 via a shaft 144 of the pinion.
A rear wheel steering angle sensor 120 such as a potentiometer is attached to detect the amount of rotation of the rear wheel. The pinion shaft 144 is rotatably supported within the housing 40 by two bearings 148 , 148 , one bearing 146 is supported by a spring 150 to support the pinion 144 .
is urged toward the rack teeth 140.

The biasing force of the spring 150 can be adjusted as appropriate by changing the screwing amount of the screw cap member 152.

In the mounting structure of the rear wheel steering angle sensor 120 described above, a rotation detection type is used as the steering angle sensor 120, and the rack teeth 140 are formed on the rear wheel steering shaft 30.
A pinion 142 disposed in the housing 40 is engaged with the shaft 144 of the pinion.
44, the steering angle sensor 120 itself, as well as the pinion 142 and pinion shaft 144, rotate but do not displace. Therefore, unlike the conventional stroke detection type Compared to the case where the steering angle sensor is used, the steering angle sensor and its mounting mechanism can be simplified and miniaturized, and it is possible to save space and improve layout.

Furthermore, the simplification and miniaturization of the mounting mechanism makes it easy to position the mounting mechanism within the housing 40, thereby solving problems such as flying stones caused by conventional external mounting, and improving mounting accuracy. I can figure it out.

Furthermore, when installing the steering angle sensor 120, it is only necessary to form a rack tooth 140 at an appropriate position on the rear wheel steering shaft 30 and mesh the pinion 142 therewith. Therefore, a special steering angle sensor mounting part is formed on the steering shaft 30. There is no need to
Therefore, there is no need to lengthen the steering shaft 30, and by shortening the steering shaft 30, it is possible to increase the degree of freedom in the geometry of the base chassis.

Further, in the case where the rear wheel steering shaft 3o is provided with the ball screw means and the centering spring means 36 as in the above embodiment, it is desirable that both means 84 and 36 be attached to the end of the steering shaft 30. . This is because, as shown in FIG. 2, the clutch 48. Brake 46, servo motor 3
2 and the encoder 114 are connected in a row, the ball screw means 34 is provided at one end of the steering shaft 30, and the clutch 48 and the like are laid out so as to extend along the steering shaft 30 toward the other end as shown. Then, the rear wheel steering shaft 3o and the clutch 48 etc. will match exactly,
Therefore, it is possible to reduce the dimension of the rear wheel steering mechanism in the vehicle width direction, and the centering spring means 36 is located at the end of the steering shaft 30 so that the centering spring means 36 is This is because the assembly to the steering shaft 30 becomes easier, and the preset load adjustment operation of the centering spring 98 using the stopper 92 and the screw cap member 104 becomes easier. Therefore, as described above, the rack teeth 140
The ball screw means 34 and the centering spring means 36
By forming the pinion between the two pinions, it is possible to rationally lay out the pinion arrangement while satisfying the requirement of arranging both the pinions 34 and 36 at the ends.

Furthermore, when the ball screw means 34 strokes the steering shaft 3o in the axial direction, a rotational force about the axis acts on the steering shaft 30, but the pinion 142 also functions as a rotation stopper for the steering shaft 30. However, when the rack teeth 140 are formed between the ball screw means 34 and the centering spring means 3B as described above, the pinion 142 that meshes with the rack teeth 140 is located approximately at the center of the steering shaft 30. Therefore, it can function as a rotation stopper much more efficiently than when it is located at the end of the steering shaft 30, for example.

(Effect of the invention) In the automobile steering angle sensor mounting structure according to the present invention,
A rotation detection type sensor is used as the steering angle sensor, and it is attached to the steering shaft via the pinion shaft, pinion and rack teeth, thereby simplifying and downsizing the steering angle sensor and its mounting mechanism as described above. It is possible to save space and improve layout. Furthermore, by simplifying and downsizing the mounting mechanism, it becomes possible to easily arrange it within the housing, thereby solving problems such as flying stones caused by external mounting.

Furthermore, there is no need to form a special steering angle sensor attachment part on the steering shaft, and the degree of freedom in the geometry of the base chassis can be increased by shortening the steering shaft.

In addition, by forming the rack teeth between the ball screw means and the centering spring means, a rational layout that satisfies the requirement that the rack teeth be attached to the ends of the steering shafts of both means becomes possible, and the pinion Since the pinion is located approximately in the center of the shaft, the pinion can fully perform its function of stopping the rotation of the steering shaft.

[Brief Description of the Drawings] Fig. 1 is a schematic diagram showing an example of a 4WS mechanism equipped with an embodiment of the present invention, Fig. 2 is a detailed sectional view of the rear wheel steering mechanism portion in Fig. 1, and Fig. 3 4 is a diagram showing an example of rear wheel steering control, FIG. 5 is a sectional view taken along the line V-V in FIG. 2, and FIG. 6 is a sectional view taken along the line ■-■ in FIG. 6L, 6R... Steering wheel 30... Steering shaft 34...
・Ball screw means 3B... Centering spring means 40... Housing 120... Rudder angle sensor 140... Rack teeth 142... Pinion 1
44...Pinion shaft Fig. 1 +20

Claims (2)

[Claims] (1) A mounting structure for a steering angle sensor that detects the steering angle of a steering wheel of an automobile, in which rack teeth are formed on a steering shaft that connects left and right steering wheels, and a housing that surrounds the steering shaft is formed on the rack teeth. 1. A steering angle sensor mounting structure for an automobile, characterized in that a steering angle sensor for detecting the amount of rotation of the shaft is attached to the shaft of the pinion, and a steering angle sensor is attached to the shaft of the pinion. (2) A mounting structure for a steering angle sensor for detecting the steering angle of a steering wheel of an automobile, which comprises: a steering shaft connecting left and right steering wheels; a centering spring means attached to the steering shaft for returning the steering shaft to a neutral position; A rack tooth is formed at a position between the ball screw means for displacing the steering shaft, and a pinion disposed in a housing surrounding the steering shaft is engaged with the rack tooth, and the rotation amount of the shaft is caused to engage with the shaft of the pinion. A steering angle sensor mounting structure for an automobile, characterized in that a steering angle sensor is mounted to detect the steering angle sensor.