JP2592975Y2 - Power steering device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus using an electric motor disposed in a steering mechanism as a source of a steering assist force.

[0002]

2. Description of the Related Art A power steering device (power steering device) applies a steering assist force to a steering mechanism in accordance with a steering torque applied to a steering wheel (steering wheel), thereby reducing a labor burden required for steering operation for steering. In recent years, it is intended to provide a light steering feeling, and in recent years, it has been widely used not only in large vehicles such as buses and trucks but also in small vehicles such as ordinary passenger vehicles and light passenger vehicles.

[0003] This type of power steering device is roughly classified into a hydraulic type using a hydraulic actuator such as a hydraulic cylinder as a source of the steering assist force and an electric type using an electric motor. With the expansion of the application range to vehicles, the latter, that is, the adoption of an electric power steering device is expanding.

The electric power steering apparatus includes a torque sensor for detecting a steering torque applied to the steering wheel in a transmission system from the steering wheel to the steering mechanism, and based on a detection result of the torque sensor, the steering mechanism. The drive current of the electric motor disposed therein is controlled to obtain a steering assist force corresponding to the steering torque. The torque sensor is configured to coaxially connect an input shaft connected to a steering wheel and an output shaft connected to a steering mechanism via a torsion bar, and to detect the steering torque through the torsion of the torsion bar. The twist of the torsion bar is obtained, for example, by extracting a change in magnetic resistance generated in a magnetic circuit formed at a connecting portion of both shafts as an impedance change of an output coil.

[0005] The input shaft and the output shaft are supported in a common housing with their respective ends coaxially butted against each other, and the torsion bar is inserted through the shaft centers of both shafts.
The other end of the input shaft projecting to the outside from the opening on one side of the housing (the end on the connection side to the steering wheel) and the butt end of the output shaft are connected to each other by separate connecting pins that are respectively installed. ing.

[0006]

In the power steering apparatus constructed as described above, when water or dust, which is jumped up from the road by the wheels while the vehicle is running, enters the housing, the torque is reduced. The detection of the steering torque by the sensor is hindered, and the steering assist based on the detection result cannot be normally performed. Therefore, conventionally, an oil seal fixed inside the opening of the housing is brought into sliding contact with the outer periphery of the input shaft, and an umbrella-shaped cover member (dust cover) whose inner edge is fitted to the protruding portion of the input shaft. And the synergistic action of the two prevents water and dust from entering the interior of the housing.

However, even in the power steering apparatus configured as described above, the effect of preventing water and dust from entering the housing, particularly, the effect of preventing water from entering is not sufficient. It has been found that this intrusion occurs through the driving hole of the connecting pin which is driven to connect the torsion bar to the projection of the input shaft as described above.

Therefore, conventionally, an O-ring is wound around the outer periphery of the torsion bar at a position inside of the connecting pin installation portion, and the O-ring is pressed against the inner periphery of the fitting portion to the input shaft to thereby press the O-ring. Although a configuration in which the intrusion path is cut off has been put to practical use, when this configuration is adopted, the formation of the O-ring winding groove involves a decrease in the torsional rigidity of the torsion bar itself, so that the desired torsional rigidity is reduced. To achieve this, it is necessary to increase the diameter of the torsion bar, which causes a problem that the input shaft and the output shaft outside the torsion bar and the torque sensor formed on the connecting portion of the both shafts are increased in size.

The present invention has been made in view of such circumstances, and water and sand and dust entering the housing of the torque sensor generated through the driving hole of the connecting pin are accompanied by an increase in the diameter of the torsion bar. It is an object of the present invention to provide a power steering device that can be effectively shut off without any trouble and can obtain satisfactory waterproof and dustproof effects.

[0010]

A power steering apparatus according to the present invention supports an input shaft connected to a steering wheel and an output shaft connected to a steering mechanism by coaxially butting in an interior of a common housing. The torsion bar inserted through the shaft center portion of the input shaft is connected to the protrusion of the input shaft to the outside of the housing and the butt portion of the output shaft with the torsion bar by connecting pins which are respectively installed. In a power steering apparatus comprising a torque sensor that detects a steering torque applied to a steering wheel by using the torsion bar as a medium, a cover member that is fitted to a protrusion of the input shaft and covers an opening of the housing. And a driving hole for the connecting pin on the protruding portion side is formed in a fitting portion of the cover member.

[0011]

According to the present invention, a connecting pin for connecting a torsion bar is provided at a fitting portion of a cover member which is fitted to the input shaft and covers the opening of the housing, and a mounting hole of the connecting pin is provided in the cover member. Prevents water and dust from entering the housing.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing an embodiment thereof. FIG. 1 is a longitudinal sectional view showing a main part of the power steering device according to the present invention. 1 the input shaft in the figure 2 is the output shaft, these two axes 1 and 2 is rotatably supported coaxially within a common sensor housing H ₁ which forms a cylindrical shape.

[0013] upper end of the input shaft 1 which projects from the upper opening of the sensor housing H ₁ Yes coupled to the steering wheel (not shown) (steering wheel), and the lower end of the input shaft 1, the interior of the sensor housing H ₁ At the upper end of the output shaft 2. The output shaft 2 is extended inside the rack housing H ₂ provided continuously on the lower side of the sensor housing H _1, and is supported at both ends and a middle portion the lower end as shown.

At the lower part of the rack housing H ₂ , a rack shaft 3 is supported so that the output shaft 2 intersects with the output shaft 2, and the rack shaft 3 is formed on the outer periphery between both support positions of the output shaft 2. The pinion 20 is engaged. Both ends of the rack shaft 3 are connected to left and right steering wheels (not shown) via respective link mechanisms. The rack shaft 3 and a pinion 20 meshing with the rack shaft 3 are connected to a rack shaft according to the rotation of the pinion 20. A known rack and pinion type steering mechanism that steers the left and right steered wheels by sliding the third wheel.

Further on one side of the upper portion of the rack housing H ₂ is the transmission housing H ₃ by crossing the housing H ₂ and the axis is continuously provided. Inside the transmission housing H _3, rotatably driving shaft 4 about the axis are supported,
At one end of the transmission shaft 4 suitable length protrudes inside of the rack housing H ₂ small bevel gear 40 is fixed, the small bevel gear 40 is coaxially fitted on the corresponding position of the output shaft 2 large bevel The gear 21 is meshed. The other end of the transmission shaft 4 is connected to the transmission housing H ₃
Is connected to the output shaft of an electric motor (steering assist motor) (not shown) fixed to the same end of the transmission shaft. The rotation of the transmission shaft 4 driven by the motor rotates the small bevel gear 40 and the large bevel gear.
The power is transmitted to the output shaft 2 via the pinion 21, and further transmitted to the rack shaft 3 via the pinion 20, so that the sliding of the rack shaft 3, that is, the steering is assisted.

The input shaft 1 is a hollow shaft provided with a cavity 10 in the axial center from the lower end to the vicinity of the upper end, and the input shaft 1 and the output shaft 2 are inserted through the cavity 10. Coaxially connected via a torsion bar 5, a torque sensor 6 is formed outside the connecting portion. The illustrated torque sensor 6 detects a change in magnetic resistance generated in a magnetic circuit formed by a detection ring fixed to each of the input shaft 1 and the output shaft 2.
And has a known configuration taken out as an impedance change in the output coil 60 which surrounds the outside of the inner fitting fixed to both detection ring sensor housing H _1. Incidentally, extraction of the feed and the output of the torque sensor 6 is performed respectively through the terminal box 7 which protrude to the outside of the sensor housing H _1.

In the power steering apparatus constructed as described above, when the steering wheel is rotated, the rotation is transmitted to the output shaft 2 via the input shaft 1 and the torsion bar 5. This is converted into sliding in the axial direction of the rack shaft 3 meshing with the pinion 20 in the lower half, and steering is performed. At this time, since the rotation of the output shaft 2 is restricted by the road surface resistance acting on the steered wheels, the torsion bar 5 connecting the input shaft 1 and the output shaft 2 has a twist corresponding to the steering torque applied to the steering wheel. This torque causes the torque sensor 6
Changes in the magnetic resistance of the magnetic circuit. Therefore, the above-described output of the torque sensor 6 corresponds to the steering torque applied to the steering wheel.

The output of the torque sensor 6 is supplied to a control unit (not shown), which is used to control the driving current of the steering assist motor. With this current control, the motor controls the magnitude of the steering torque applied to the steering wheel. As described above, this torque is transmitted to the output shaft 2 via the transmission shaft 4 and further transmitted to the rack shaft 3 via the pinion 20, as described above. The steering performed as described above is assisted by the rotational force of the steering assist motor.

The above operation is performed by the torque sensor 6
And the detection of the steering torque assumes to be performed normally due to, in order to ensure proper detection, to prevent water and dust from entering the interior of the sensor housing H ₁ for accommodating the torque sensor 6 is important. Communicating portion between the inside and the outside of the sensor housing H ₁ is substantially the input shaft 1
Is only the opening on the protruding side.

[0020] Figure 2 is the input shaft 1 is an enlarged cross-sectional view of the upper opening near the sensor housing H ₁ projecting. The upper opening of as illustrated sensor housing H _1, the oil seal 11
There are internally fitted fixed, the inner periphery of the lip of the oil seal 11, are brought into sliding contact with the outer periphery of the input shaft 1 to prevent foreign material from entering the interior sensor housing H _1. Furthermore, the upper opening of the sensor housing H ₁ is a rubber dust cover 12 that forms the umbrella which is fitted the inner peripheral edge to the input shaft 1 is covered over as shown entirely. That is, in the upper opening of the sensor housing H _1, the oil seal 11
The inside and outside communication is cut off by a double sealing structure composed of the dust cover 12 and the dust cover 12, thereby preventing intrusion of water and dust.

[0021] Now, the connection between the input shaft 1 and the torsion bar 5, the projecting portion of the input shaft 1 from the sensor housing H _1, pouring penetrating the said input shaft 1 and an inner torsion bar 5 in the radial direction A hole 13 is formed, and a connecting pin
It has been done by placing 14. Similarly, the connection between the output shaft 2 and the torsion bar 5 is made by inserting an appropriate length insertion hole 22 (FIG.
Is formed, the lower end of the torsion bar 5 is fitted into the insertion hole 22, and the connecting pin 16 is driven into the driving hole 15 penetrating the output shaft 2 and the torsion bar 5 in the radial direction. .

[0022] The pouring of the connecting pin 14 for coupling the input shaft 1 and the torsion bar 5 is performed outside of the sensor housing H _1, the torque in the interior of the sensor housing H ₁ remains without connecting the torsion bar 5 This is because it is necessary to assemble the sensor 6, adjust the zero point of the torque sensor 6 while finely adjusting the rotational position of the input shaft 1 from the outside, and then connect the input shaft 1 and the torsion bar 5 to the present invention. the power steering apparatus according, as shown in FIGS. 1 and 2, the droplet設孔13 of the connecting pin 14 positioned on the outside of the sensor housing H ₁ is located to form within the fitting range of the dust cover 12 The feature is that both sides of the driving hole 13 are completely covered by the inner edge of the dust cover 12.

Accordingly, the water that has been splashed up from the road surface by the wheels during traveling is transmitted from the opening of the driving hole 13 to the input shaft 1.
Of invaded inside, there is no fear to invade the sensor housing H ₁ through the inner cavity 10 of the input shaft 1, a synergy between the sealing by the oil seals 11 and dust cover 12, the sensor housing H ₁ to the inside Water and dust can be almost completely prevented, and there is no possibility that the normal detection of the steering torque by the torque sensor 6 is hindered.

FIG. 3 is an enlarged sectional view of the vicinity of the connection between the output shaft 2 and the torsion bar 5. As shown in FIG. 1, the large bevel gear 21 fitted in the middle of the output shaft 2 is positioned and fixed from below by a lock nut 23 screwed into a threaded portion of the output shaft 2. As shown in FIG. 3, a thin caulking rim 24 is provided around the lower portion of 23. Connecting pin 16
The driving hole 15 is formed slightly below the screwing position of the lock nut 23, and the caulking edge 24 is bent inward at a position aligned with the openings on both sides of the driving hole 15. In other words, by this deformation, the locking of the lock nut 23 after the completion of the tightening and the locking of the connecting pin 16 from the driving hole 15 can be simultaneously achieved.

On the other hand, measures for waterproofing and dustproofing are also required at the opening of the terminal box 7, and for this purpose, in the illustrated embodiment, a rubber cover member is provided at the opening of the terminal box 7. 17 are installed.

FIG. 4 is an explanatory view of the procedure for attaching the cover member 17. Outside the opening of the terminal box 7, an engaging groove 18 having a predetermined width and depth is provided around the entire circumference, and inside the peripheral portion of the cover member 17, the engaging groove is provided. A pair of engagement projections 19, 19 having a length corresponding to the depth of 18, are provided to project inwardly at intervals corresponding to the width of the engagement groove 18 over the entire circumference. As shown in FIG.
(A), an outward force is applied to the peripheral edge as shown by the white arrow therein, the peripheral edge is expanded as shown by the two-dot chain line, and is placed over the opening of the terminal box 7, and the inner engaging projections 19, 19 Is fitted into the engaging groove 18 of the terminal box 7, and as shown in FIG.
A fastening ring R is wound around the outside of the projecting portions 19 and 19.

The engagement projections 19 of the cover member 17 attached as described above are elastically deformed in the engagement groove 18 by the inward tightening force of the tightening ring R as shown in FIG. It is strongly pressed against the inner wall of the engagement groove 18 and is brought into close contact therewith. Therefore, the inside of the terminal box 7 is provided with the engagement projections 19, 19.
Are sealed off from the outside by the double sealing portion due to the close contact of each with the engaging groove 18, and it is possible to effectively prevent water and dust from entering the terminal box 7.

In this embodiment, an example of application to a rack and pinion type steering mechanism has been described. However, the scope of the present invention is not limited to this.
It goes without saying that application to other types of steering mechanisms is also possible.

[0029]

As described above in detail, in the power steering apparatus according to the present invention, the cover for covering the opening of the housing is provided with the connecting pin driving hole for connecting the projecting portion of the input shaft to the upper part of the housing to the torsion bar. Since the formation hole is formed at the fitting portion of the member, the driving hole is covered with a cover member, which can effectively prevent water and dust from entering the inside of the housing through the driving hole, thereby increasing the diameter of the torsion bar. The present invention has excellent effects such as satisfactory waterproof and dustproof effects being obtained without inviting.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a power steering device according to the present invention.

FIG. 2 is an enlarged cross-sectional view near an upper opening of a sensor housing.

FIG. 3 is an enlarged cross-sectional view near a connecting portion between an output shaft and a torsion bar.

FIG. 4 is an explanatory view of a procedure for attaching a cover member for sealing the terminal box.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Input shaft 2 Output shaft 4 Transmission shaft 5 Torsion bar 6 Torque sensor 7 Terminal box 11 Oil seal 12 Dust cover 13 Driving hole 14 Connection pin 15 Driving hole 16 Connection pin H ₁ sensor housing H ₂ rack housing H ₃ transmission housing

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B62D 5/04

Claims (1)

(57) [Scope of request for utility model registration] An input shaft connected to a steering wheel and an output shaft connected to a steering mechanism are coaxially butted and supported in a common housing, and a torsion bar inserted through a shaft portion of the input shaft is connected to the input shaft. The protruding portion of the shaft to the outside of the housing and the butting portion of the output shaft with the torsion bar are connected by connecting pins which are respectively provided so that the steering torque applied to the steering wheel is transmitted through the torsion of the torsion bar. A power steering device comprising a torque sensor configured to detect a position of the input shaft; a cover member fitted to the protrusion of the input shaft to cover an opening of the housing; A power steering device, wherein a driving hole for the connecting pin is formed.