JPH0432966B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a rack and pinion type power steering device suitable for use in reducing the operating force (steering force) of a steering wheel by a driver, and particularly relates to a power steering device of a rack and pinion type suitable for use in reducing the operating force (steering force) of a steering wheel by a driver. The present invention relates to a steering angle displacement detection device that is equipped with a steering angle displacement amount sensor suitable for use in performing appropriate steering force control according to various driving conditions.

[Prior art]

Power steering devices are generally referred to as power steering devices, and in recent years have been widely installed in various vehicles, including small cars, to reduce the steering force of the driver and enable easy and nimble steering operations. This can also be effective in reducing driver fatigue. In particular, the rack and pinion type of this type of power steering device is
In terms of installation space and ease of incorporation into the vehicle,
It is superior to other types, and in recent years it has been widely used in various types of vehicles. As such rack and pinion type power steering devices, hydraulic types have traditionally been well known, and in recent years, in addition to these, electric types using electric motors have been proposed. It's getting old.

By the way, the problem with the above-mentioned power steering system is the steering force and steering angle according to the driver's steering operation. Furthermore, the structure is such that the operation of the device can be appropriately controlled under various running conditions such as the running speed of the vehicle, and steering assist force can be obtained as needed. In other words, for vehicles equipped with this type of power steering device, extremely light steering force can be obtained when performing steering operations when the vehicle is stationary, so-called stationary operations, or when driving at low speeds. It is necessary to have a configuration that can output a large steering assist force, and it can be used in such cases to exhibit its effect. However, on the other hand, if a large steering assist force is generated when the vehicle is traveling at high speed, as described above when traveling at low speed, the operating force of the steering wheel becomes too light.
This leads to problems such as increasing the driver's sense of anxiety, which is not practical in terms of optimizing the driving sensation. In other words, a configuration that increases the steering force is required.

In order to meet these demands, the various power steering devices described above must be adapted to the driving conditions of the vehicle.
It is necessary to drive the vehicle in a controlled manner depending on the traveling speed, the magnitude of the steering force, and even the large or small steering angle, and for this purpose, various detection devices must be attached. .

In other words, in the above-mentioned power steering device of the hydraulic type, a solenoid valve or the like is used to appropriately control the discharge flow rate from the oil pump driven by the engine according to the various conditions mentioned above. In addition, in order to meet the recent demand for energy saving, it is also desirable to control oil pumps and other equipment on and off via electromagnetic cracks, and the above-mentioned detection devices are becoming important. It is something that

Furthermore, the above-mentioned requirements are also required for the type of power steering device that uses an electric motor to ensure operational reliability and durability of each part, as well as proper control. This is because when using an electric motor, it is difficult to obtain operating characteristics that follow the steering operation of the steering wheel due to the inertia of the motor, and furthermore, due to the presence of a deceleration mechanism between the steering shaft and the motor, it is difficult to obtain operating characteristics that follow the steering operation of the steering wheel. It is obvious that even when returning the steering wheel to its original neutral position, it is necessary to detect the steering conditions of the driver and reverse the motor. In other words, in a steering device equipped with a power steering device, when the steered wheels return from a turning state to a straight-ahead state, generally self-aligning torque ( However, in the above-mentioned motor, there is friction in the brushes, etc., and this generates an acting force that resists the rotation of the rotor, causing self-alignment. The lining torque alone was insufficient to rotate the rotor in reverse, and it was necessary to compensate for this deficiency.

For this reason, various configurations of the above-mentioned detection mechanisms have been known, but all of them have structural disadvantages in terms of operational performance.
This is particularly important in the steering angle displacement detection mechanism that detects, for example, in which direction and at what steering angle the driver turns the steering wheel from the neutral position, so it is especially important to consider the method of its construction. , various problems arise in terms of mechanism arrangement position, detection performance, etc., and it is desired that some kind of countermeasure be taken.

In other words, conventionally known steering angle displacement detection devices are generally configured with a rotation sensor such as a potentiometer that decelerates the rotation of the steering shaft using gears, belts, etc. Since the above-mentioned steering wheel is rotated in both the left and right directions from the neutral position for at least two or more rotations, it cannot be simply applied. In other words, the rotation sensor described above not only requires a deceleration mechanism to decelerate the steering operation of the steering wheel within one rotation, making its structure complicated, but also requires an analog output signal. Since it is a signal, in order to use it for controlling a power steering device, it is necessary to adopt a structure that is cumbersome and complicates the circuit configuration once it is converted to a digital signal. This caused problems such as increased costs.

Additionally, a structure in which the amount of displacement of a portion that is linearly displaced is detected by a potentiometer is known, but in this case as well, the structure is complicated as in the case described above, and furthermore, the output It is also necessary to convert it into a digital signal and use it.
Furthermore, with such a configuration, it is difficult to obtain reliable measurement accuracy, which poses a major practical problem.

In particular, the above-mentioned steering angle displacement detection device is highly needed when it is employed in an electric power steering device using an electric motor.
In other words, in this type of electric power steering device, when returning the steered steering wheel to the neutral position, the self-aligning torque is generally used to automatically return the steered steering wheel to the neutral position, as in manual steering or hydraulic power steering devices. As mentioned above, it is difficult to return to normal state, and normally a configuration is adopted in which the motor is reversed to return to normal state. However, the problem with adopting such a configuration is that, as is well known, the steering wheel used in vehicles, etc. is usually rotated two or more turns in both directions from the neutral position. Therefore, in order to detect the amount of rotation, it is difficult to put a generally well-known rotary sensor into practical use. In addition, the above-mentioned steering angle displacement amount sensor can appropriately determine the amount of steering angle displacement even when the engine is temporarily stopped with the steered wheels deflected, and then the engine is started again and a steering operation is performed. There is also a need for a function that can restore the system, and it is desired that some kind of countermeasure be taken to satisfy such a request.

Furthermore, as described above, the steering angle displacement amount sensor is transmitted by the steering shaft on the upstream side (steering handle side) of the rack and pinion that mesh as a steering gear that transmits the steering angle displacement amount sensor from the steering wheel to the steering link mechanism on the steering wheel side. In the structure provided as part of the system, reliability in terms of detection accuracy is required when detecting the amount of steering angular displacement (deflection) on the steering wheel side, which is also affected by backlash from the ground contact side. Therefore, consideration must be given to these points as well.

Such a requirement applies to a hydraulic power steering system in which a motor is combined as a steering assist force sending means.Furthermore, even in a hydraulic power steering system, for example, the height of the vehicle, Hydraulic reaction force control to control the stiffness of the steering wheel when driving at low speeds, and the oil pump being inactive and disconnected from the engine when driving in a straight line, are necessary and require improvement. ing.

[Summary of the invention]

The present invention has been made in view of the above circumstances, and includes a part of the rack constituting a rack and pinion type steering link mechanism that deflects the steered wheels in accordance with the steering operation using the steering handle. With a simple configuration that includes a steering angle displacement amount sensor that detects the amount of displacement in the axial direction due to operation and outputs a digital signal, the detection section is easy to directly detect the movement of the steered wheel side. Therefore, the amount of steering angle displacement can be easily and accurately detected, the overall configuration is simplified, manufacturing is easy, and costs can be reduced, and the detection accuracy is also reliable. This makes it possible to obtain an appropriate and smooth steering assist force according to the vehicle's driving conditions and to demonstrate the performance of the device.Furthermore, it is possible to obtain digital signals directly from the sensor, making it possible to improve The object of the present invention is to provide a steering angle displacement detection device for a power steering device that has various excellent advantages such as eliminating the need for analog-to-digital conversion.

〔Example〕

Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

1 to 3 show an embodiment of the steering angle displacement amount detection device for a power steering device according to the present invention, and in these figures, the steering angle displacement amount detection device which is the main part thereof is shown. Only the rack and pinion type steering mechanism section 1 with the attached steering mechanism 10 is shown.

First, this steering link mechanism 1 is
To explain briefly using the figure, reference numeral 2 in the figure is a steering shaft extending from a steering wheel (not shown), the tip of which is fitted into the steering body section 3, and a pinion (see figure 2). (not shown), and this pinion is meshed with a rack 5 constituting a steering linkage 4 that is suspended between steering wheels (not shown) of the vehicle. In addition, in the figure, 6 is a king pin provided on both ends of the steering link mechanism 4 and connected to the pitman arm side on the steered wheel side, 7 is a tie rod connected to this, and the rack 5 is interposed between the tie rods 7 on both sides. They are installed in a series in a state that Further, 8 is a housing that surrounds the steering link mechanism 4, and is provided with mounting brackets 9a, 9b, etc. that are assembled on the vehicle side, and bellows-shaped elastic cylinders 8a, 8b are arranged at both ends of the housing. It has a structure that ensures sealing performance from other parts.

Now, according to the present invention, in the rack and pinion type steering mechanism 4 that deflects the steered wheels in response to a steering operation, the rack and pinion type steering mechanism 4 is arranged between the steered wheels along the width direction of the vehicle and is moved linearly in the left-right direction of the vehicle. The rod portion 5a that connects the rack 5 and the tie rod 7 is equipped with a steering angle displacement sensor 11 that detects the amount of displacement in the axial direction and sends out a detection signal. .

To explain this in detail, the above-mentioned steering angle displacement amount sensor 11 is connected to a rod portion 5a that moves together with the rack 5, as shown in FIGS. 2 and 3.
Five sliders 14a are provided at the tip of a lever 13 that protrudes to the outside through a long groove 12 bored in one side of the housing 8 along its axial direction.
14e, and five rows of wiring patterns 15a to 15e according to a binary system that can send out a desired detection signal by sliding contact between these sliders 14a to 14e.
and a printed circuit board 17 on which the common wiring 16 is printed. The printed circuit board 17 is fixed to the outer side of the housing 8 with a mounting bracket 18. Then, the wiring patterns 15a to 15e and the common wiring 16 are brought into conduction with each other, and a + voltage is applied to the common wiring 16 side.
In addition, a five-digit digital signal with conduction 1 or blank 0 is sent out from the leads (not shown) pulled out from the sliders 14a to 14e that are in sliding contact with the respective wiring patterns 15a to 15e.
The axial position of the steering wheel, that is, the steering angle position of the steering wheel is detected.

Here, the wiring patterns 15a to 15e on the printed circuit board 17 mentioned above and the slider 1 in sliding contact therewith.
The problem in configuring the steering angle displacement amount sensor 11 with 4a to 14e is that when the rack 5 is located at a position straddling the sections divided at predetermined intervals in the displacement direction. This is detection accuracy. In order to solve this problem, as shown in FIG. 4, a slider 14f for transmitting a holding signal when positioned across the above-mentioned circles and a wiring pattern on which it slides are developed. 19, and when the slider 14f is located in the blank part 19a, the control state based on the read signal just before is maintained, and when this state is released, the position detection operation is performed. It is sufficient if the configuration is as follows.

According to such a configuration, the steering angle of the steering wheel can be easily and appropriately detected based on the amount of movement of the rack 5, tie rod 7, etc., and thereby the amount of steering angle displacement of the steering wheel can be detected. .
In particular, in such a configuration, since the displacement by the rod portion 5a of the rack 5 that moves with the movement of the steered wheel side is detected, the actual amount of steering angle displacement of the steered wheel can be obtained. This method is superior in terms of reliability, etc., compared to the case where the steering angle is detected indirectly by the movement of the steering link mechanism 4 on the steering wheel side. Further, according to the steering angle displacement amount sensor 11 according to the present invention, the configuration can be simplified and the cost can be reduced compared to the case where a conventional rotary type sensor is used. Therefore, the detection accuracy is greatly improved, and in particular, there is an advantage that the accuracy does not deteriorate due to changes over time or temperature changes. In particular, according to this embodiment, the contacts (wiring patterns 15a to 15e; 16) according to the binary system are printed on the printed circuit board 17, etc., and the output can be directly sent as a digital signal, which is different from the conventional method. There is an advantage that an A/D converter or the like is not required.

Therefore, according to the steering angle displacement amount detection device 10 according to the present invention having the above-described configuration, the steering angle displacement amount can be easily and accurately detected with a simple configuration, and the overall configuration is simplified. This makes it easy to manufacture, reduces costs, and greatly improves the reliability of detection accuracy. Its effects are great, such as being able to obtain steering assist force and exhibiting the performance of the device, and also preventing conventional analog-to-digital conversion from being defective.

In addition, FIG. 5 shows each slider 14a to 14 when the printed circuit board 17 having the wiring patterns 15a to 15e, 19; 16 shown in FIG. 4 described above is used.
In this case, 1 in the figure shows the output signals from the slider 14f, and 2 to 6 show the output signals from the sliders 14a to 14e.

Further, in the above-described embodiment, a case has been described in which a lead serving as a signal extraction means from the steering angle displacement amount sensor 11 is pulled out from the movable side of the sliders 14a to 14e, 14f. For example, without limitation, as shown in FIGS. 6a, b, c, and d, the leads 20, 21a to 21e are pulled out from the fixed side of the printed circuit board 17, and the leads 2
At the same time as applying a positive voltage at 0, the detection signals at each slider 14a to 14e are sent to the leads 21a to 2.
Of course, the signal may be sent to the controller 22 side at 1e. Here, 23a in the figure
- 23e are electrically connected to the sliders 14a to 14e, respectively, and slide on the back side of the printed circuit board 17, and 24a to 24e are formed on the back side corresponding to the wiring patterns 15a to 15e on the front surface of the board, as described above. The operation and effect of the wire leads 21a to 21e drawn out and to which the sliders 23a to 23e come into sliding contact will be easily understood.

According to the steering angle displacement amount detection device 10 having the above configuration, the steering angle displacement amount of the steered wheels can be appropriately and reliably detected despite the simple and inexpensive configuration, and therefore it is applicable to various power steering devices. It is possible to achieve its effects by doing so. That is, according to the steering angle displacement amount detection device according to the present invention, the amount of deflection of the steered wheel can be reliably detected based on the amount of movement in the axial direction of the rack 5 that constitutes a part of the steering link mechanism 4. Therefore, when this is applied to an electric power steering device, the returning operation of the steering wheel, which is a problem, can be easily controlled by a motor. These advantages also apply to a power steering system in which a motor is combined with a hydraulic system.

Additionally, in hydraulic power steering systems, electromagnetic clutches are used to control hydraulic reaction force to optimize steering force control at high and low speeds, or to disconnect the oil pump from the engine when driving straight ahead. It is also clear that it can be used as a control means to increase the steering force as the steering angle becomes larger, to achieve its effect.

Note that the present invention is not limited to the structure of the embodiment described above, and the shape, structure, etc. of each part may be modified and changed as necessary. For example, in the steering angle displacement amount detection device 10 with the linear digital binary sensor structure as described above, the wiring pattern 1 on the printed circuit board 17 constituting this device
The position detection divisions such as 5, 16, and 19 may be increased or decreased as required.

As explained above, according to the steering angle displacement amount detection device for a power steering device according to the present invention, the rack and pinion type steering link mechanism that deflects the steered wheels in accordance with the steering operation by the steering handle can be used. A steering angle displacement amount sensor that detects the amount of displacement in the axial direction and outputs a digital signal is installed in some parts, so despite the simple configuration, it is possible to follow the movement of the steered wheels and this Since the steering displacement amount detection section is a rack that can directly detect the movement of the steering wheel side, the amount of steering angle displacement can be detected easily and accurately, and the overall configuration is simplified, making it easy to manufacture. With,
It is possible to reduce costs and significantly improve the reliability of detection accuracy, thereby obtaining appropriate and smooth steering assist force according to the vehicle's driving conditions and demonstrating the device's performance. Furthermore, since digital signals can be obtained directly at the sensor, there are various excellent effects such as eliminating the need for conventional analog-to-digital conversion.
Further, according to the present invention, the steering angle displacement amount sensor is
It is possible to select and install the sensor at any position on the rack, which has a large degree of freedom in terms of installation space, taking into consideration space for installation into the vehicle, etc., and it is also possible to install the sensor at any position during assembly between the sensor and the rack. It also has the advantage of being easy to perform.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing a steering mechanism section showing an embodiment of a steering angle displacement amount detection device for a power steering device according to the present invention, and FIG. 2 is a schematic perspective view showing an enlarged view of the main parts thereof. FIG. 3 is a schematic plan view showing an example of the wiring pattern of the printed circuit board constituting the steering angle displacement amount sensor, FIG. 4 is a schematic plan view showing a modification thereof, FIG. 5 is a waveform diagram of the output signal, and FIG. Figures 6a, b, c, and d are a plan view, a front view, a bottom view, and a sectional view of main parts showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Steering mechanism part, 2... Steering shaft, 4... Steering link mechanism, 5
...Rack, 5a...Rod portion, 7...Tie rod, 8...Housing, 10...Steering angle displacement amount detection device, 11...Steering angle displacement amount sensor, 12...
Long groove, 13... Lever, 14a to 14e, 14f
...Slider, 15a to 15e...Wiring pattern,
16... Common wiring, 17... Printed circuit board, 19
...Wiring pattern, 19a...Blank area, 20,2
1a to 21e...Lead, 22...Controller, 23a to 23e...Slider, 24a to 24e
...Wiring lead.

Claims (1)

[Scope of Claims] 1. In a power steering device comprising a rack and pinion type steering link mechanism that deflects steered wheels in response to a steering operation using a steering handle, a part of the rack constituting the steering link mechanism includes: A steering angle displacement amount detection device for a power steering device, characterized in that a steering angle displacement amount sensor is provided that outputs a digital signal by detecting the amount of displacement in the axial direction accompanying the steering operation of the rack. .