JP3579474B2 - Shock absorbing power steering device - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a power steering device capable of absorbing a shock acting on a driver at the time of a vehicle collision.
[0002]
[Prior art]
A conventional shock-absorbing power steering device 101 shown in FIG. 10 includes a first column 102, a second column 103 which is press-fitted via a ball 106 to the first column 102 so as to relatively move in the axial direction at the time of impact. A handle shaft 104 inserted into the columns 102 and 103 and a torque sensor 105 for detecting a torque transmitted by the handle shaft 104 are provided. The outer periphery of the housing 105a of the torque sensor 105 is press-fitted into one end of the second column 103, whereby the inner periphery of the second column 103 is supported by the outer periphery of the housing 105a.
[0003]
The handle shaft 104 is connected to a first handle shaft 104a connected to a steering wheel (not shown) via a resin 107 so as to be able to transmit rotation to the first handle shaft 104a and to move relatively in the axial direction when an impact is applied. A second handle shaft 104b, a third handle shaft 104c connected to the second handle shaft 104b via a pin 109, and a relatively rotatable connection to the third handle shaft 104c via a torsion bar 108 in accordance with steering resistance. And a fourth handle shaft 104d. The fourth handle shaft 104d is connected to a steering wheel (not shown). The third handle shaft 104c is supported by a housing 105a of the torque sensor 105 via a bearing 110, and the fourth handle shaft 104d is supported by a housing 105a of the torque sensor 105 via bearings 111 and 112.
[0004]
The torque sensor 105 passes through a first detection ring 115 made of a magnetic material fitted to the third handle shaft 104c and a second detection ring 116 made of a magnetic material fitted to the fourth handle shaft 104d. A first detection coil 117 for generating a magnetic flux, a second detection coil 119 for generating a magnetic flux passing through the first detection ring 115 and a third detection ring 118 made of a magnetic material fitted to the third handle shaft 104c; Having. The first and second detection rings 115 and 116 have teeth formed at equal intervals in the circumferential direction, and the area of the opposing portions of the teeth is determined by the twist of the torsion bar 108 due to steering resistance. It changes according to the relative rotation. Since the magnetic resistance between the opposing teeth changes due to this change, the output of the first detection coil 117 changes according to the change, and the transmission torque is detected according to the output. The output of the motor 120 driven according to the detected torque is transmitted to the fourth handle shaft 104d via the gears 131 and 132, so that a steering assist force is applied.
[0005]
Further, teeth are formed on the end face of the third detection ring 118 facing the first detection ring 115 at equal intervals in the circumferential direction, and the teeth are formed on the end face of the first detection ring 115 facing the third detection ring 118. Is not formed. The magnetic resistance corresponding to the distance between the first detection ring 115 and the third detection ring 118 corresponds to the distance between the first detection ring 115 and the second detection ring 116 in a state where the steering resistance is not acting. To be equal to the magnetic resistance. Thus, the output fluctuation of the first detection coil 117 due to the temperature fluctuation is made equal to the output fluctuation of the second detection coil 119 due to the temperature fluctuation. As shown in FIG. 11, the first detection coil 117 is connected to the oscillator 121 via the resistor 120, and the second detection coil 119 is connected to the oscillator 121 via the resistor 123. Each of the coils 117 and 119 is connected to the differential amplifier circuit 125. Thereby, the output fluctuation of the first detection coil 117 due to the temperature fluctuation is compensated. In order to determine the axial position of the third detection ring 118 with respect to the third handle shaft 104c, a protrusion 104c 'is formed on the outer periphery of the third handle shaft 104c, and the third detection ring 118 contacts the protrusion 104c'. Touch
[0006]
According to the above configuration, the impact energy can be absorbed by plastically deforming each of the columns 102 and 103 by the ball 106 when the columns 102 and 103 are moved relative to each other in the axial direction due to the impact. The axial relative movement amount is determined by a distance L until the first column 102 collides with the housing 105a of the torque sensor 105.
[0007]
[Problems to be solved by the invention]
In order to sufficiently absorb the impact energy, it is desirable to increase the axial relative movement between the first column 102 and the second column 103. However, the size of the vehicle body is limited, and particularly in the case of a mini vehicle, the size is severe. Therefore, the conventional structure cannot secure a sufficient amount of relative movement of the columns 102 and 103 in the axial direction. For this reason, a taper portion 103a is formed on the outer periphery of the second column 103 to increase the amount of plastic deformation, and a spring 130 for absorbing shock is provided inside the column. However, processing and assembly are troublesome and cost increases. Was the cause.
[0008]
An object of the present invention is to provide a shock absorbing power steering device that can solve the above problems.
[0009]
[Means for Solving the Problems]
The present invention detects a first column, a second column inserted into the first column so as to move axially relative to each other when an impact is applied, a handle shaft inserted into both columns, and a transmission torque by the handle shaft. And a torque sensor that applies a steering assisting force corresponding to the detected torque. An outer periphery of the second column is supported by an inner periphery of a housing of the torque sensor. The outer periphery of the handle shaft is supported via the support member by the inner periphery of the column.
[0010]
The torque sensor has a detection ring fitted to the handle shaft, the support member has a split groove and is a bush that can be elastically expanded and reduced in the radial direction, and the bush is provided on the outer periphery of the handle shaft. The bush is reduced in the radial direction by being fitted into the formed circumferential groove and forming a protrusion extending in the axial direction at one end of the bush, and the protrusion being inserted into the inner periphery of the detection ring. It is preferable that the detection ring is held in the state of being moved, and the axial movement of the detection ring is prevented by one end surface of the circumferential groove through the bush.
[0011]
Function and Effect of the Invention
According to the configuration of the present invention, the outer periphery of the second column is supported by the inner periphery of the housing of the torque sensor, and the outer periphery of the handle shaft is supported by the inner periphery of the second column via the support member. The column can be inserted into the housing up to a position overlapping the support member. This makes it possible to reduce the axial dimension of the housing as compared with the case where the second column and the support member are individually supported by the housing. Therefore, even if the size of the vehicle body is limited, the first column does not collide with the housing. Is increased, the amount of impact energy absorption is increased by ensuring a sufficient amount of axial relative movement between the first column and the second column, and assembly and processing are simplified and costs can be reduced.
[0012]
Since the support member has a split groove and is a bush that can be elastically enlarged and reduced in the radial direction, the bush can be easily fitted into a circumferential groove formed on the outer periphery of the handle shaft. The bush can be held in a radially reduced state only by inserting the protruding portion at one end of the bush into the inner periphery of the detection ring, so that the assembling work is facilitated. The detection ring is prevented from moving in one axial direction by one end surface of the circumferential groove through the bush, whereby the detection ring can be positioned in the axial direction with respect to the handle shaft, thereby also facilitating the assembly work. Become. Further, by supporting the handle shaft with a bush instead of a bearing, the cost can be reduced.
[0013]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
The shock-absorbing electric power steering device 1 shown in FIG. 1 includes a cylindrical first column 2a and a second column 2b, and the axis of each of the columns 2a and 2b is arranged on the vehicle body so as to be downward toward the front of the vehicle body. It is attached. As shown in FIG. 5, the first column 2a is press-fitted into the second column 2b via the tubular member 3, and the press-fit load is set so as to properly absorb impact energy.
[0015]
The first column 2a supports a cylindrical first handle shaft 5 via a bearing (not shown). The first handle shaft 5 and the first column 2a are engaged at an unillustrated position so that the first handle shaft 5 and the first column 2a can move together in the axial direction when an impact is applied. A steering wheel (not shown) is connected to one end of the first handle shaft 5, and one end of the second handle shaft 7 is inserted into the other end. A pair of peripheral grooves 8 are formed on the outer periphery of the second handle shaft 7, a through hole 9 communicating with the peripheral groove 8 is formed in the first handle shaft 5, and a resin 60 is formed in the through hole 9 and the peripheral groove 8. Is filled. When an impact is applied, the resin 60 is broken, and the first handle shaft 5 and the second handle shaft 7 move relatively in the axial direction. As shown in FIG. 7, since the inner peripheral shape of the first handle shaft 5 and the outer peripheral shape of the second handle shaft 7 are non-circular, the rotation of the first handle shaft 5 and the second handle shaft 7 is transmitted. It is connected as possible.
[0016]
As shown in FIGS. 1 and 2, one end of the second column 2 b is press-fitted into an inner peripheral hole 71 a of a sensor housing 71 of the torque sensor 70. The outer periphery is supported. In order to determine the axial position of the second column 2b with respect to the sensor housing 71, a protrusion 71b is formed on the inner periphery of the sensor housing 71, and the end surface of the second column 2b abuts on the protrusion 71b.
[0017]
The third handle shaft 73 and the torsion bar 78 are connected to the other end of the second handle shaft 7 via the pin 91, and the fourth handle shaft 74 is connected to the torsion bar 78 via the pin 92. The third handle shaft 73 and the fourth handle shaft 74 are relatively rotatable according to the steering resistance. The outer periphery of the third handle shaft 73 is supported by the inner periphery of the second column 2b via a bush (support member) 94. The outer periphery of the fourth handle shaft 74 is supported by the inner periphery of the sensor housing 71 via bearings 80a and 80b. The fourth handle shaft 74 is connected to a steering wheel (not shown).
[0018]
The torque sensor 70 detects a steering torque transmitted from the third handle shaft 73 to the fourth handle shaft 74. That is, a first detection ring 81 made of a magnetic material is fitted around the outer periphery of the third handle shaft 73, and a second detection ring 82 made of a magnetic material is fitted around the outer periphery of the fourth handle shaft 74. A first coil holder 88 made of a magnetic material that holds the first detection coil 83 and a second coil holder 89 made of a magnetic material that holds the second detection coil 84 are attached to the inner periphery of 71.
As shown in FIG. 2, one end of the first detection ring 81 and one end of the second detection ring 82 face each other, and teeth 81a and 82a are formed on each of the facing end faces at equal intervals in the circumferential direction. The second detection coil 84 is disposed so as to cover a space between the two detection rings 81 and 82 and generates a magnetic flux passing through the two detection rings 81 and 82.
The first detection coil 83 is arranged so as to cover the outer periphery on the other end side of the first detection ring 81 and generates a magnetic flux passing through the first detection ring 81. The area of the opposing portion of the teeth 81a, 82a changes according to the relative rotation of the two detection rings 81, 82 based on the torsion of the torsion bar 78 due to steering resistance. Due to this change, the magnetic resistance between the opposing teeth 81a and 82a changes, so that the output of the second detection coil 84 changes according to the change, and the transmission torque is detected corresponding to the output. The other end of the first detection ring 81 is a small-diameter portion 81b having a smaller outer diameter than the one end. The side wall portion 88a of the first coil holder 88 is disposed so as to face the small-diameter portion 81b on the other end side of the first detection ring 81, and the side wall portion 88b of the first coil holder 88 is connected to the first detection ring 81. Is arranged so as to face one end of the. The magnetic resistance of the magnetic circuit formed by the first detection ring 81 and the first coil holder 88 is equal to the first detection ring 81, the second detection ring 82, and the second coil holder 89 in a state where no steering torque is applied. The outer diameter of the small diameter portion 81b is set to be equal to the magnetic resistance of the magnetic circuit constituted by Thus, the output fluctuation of the first detection coil 83 due to the temperature fluctuation is made equal to the output fluctuation of the second detection coil 84 due to the temperature fluctuation, and the output fluctuation of the second detection coil 84 due to the temperature fluctuation can be compensated. The temperature compensation can be performed by, for example, a circuit configuration similar to the conventional one shown in FIG.
[0019]
A worm wheel 85 is fitted around the outer periphery of the fourth handle shaft 74, and the worm wheel 85 is meshed with a worm gear 87 fitted to an output shaft of a steering assist motor 86 attached to the sensor housing 71. When the motor 86 is driven according to the torque detected by the torque sensor 70, a steering assist force according to the detected torque is applied.
[0020]
As shown in FIG. 4, the bush 94 has a split groove 94a and is elastically expandable and contractible in the radial direction. The bush 94 has a protruding portion 94b extending in the axial direction at one end thereof, and is made of, for example, a resin such as oil-impregnated polyacetal. Can be configured. As shown in FIG. 3, the bush 94 is fitted into a circumferential groove 73 a formed on the outer circumference of the third handle shaft 73, and the protrusion 94 b is inserted into the inner circumference of the first detection ring 81, It is held in a state reduced in the radial direction. The movement of the first detection ring 81 in one axial direction is prevented by the one end face 73a 'of the circumferential groove 73a via the bush 94. Thus, the first detection ring 81 is positioned in the axial direction.
[0021]
As shown in FIGS. 5 to 8, the first column 2 a is attached to the vehicle body side member 45 via the upper bracket 11. The upper bracket 11 is welded to the first column 2a, and a pair of side walls 11a, 11b, a connecting wall 11c connecting one end of each side wall 11a, 11b, and a first column 2a from the other end of each side wall 11a, 11b. And supporting portions 11d and 11e extending radially outward.
Notches 11d ', 11e' opening on the steering wheel side are formed in the support portions 11d, 11e, and connecting members 20, 21 are inserted into the notches 11d ', 11e'. That is, a pair of grooves 20a ', 20b', 21a ', 21b' are formed in each connecting member 20, 21 along the column axis direction, and each groove 20a ', 20b', 21a ', 21b' has a supporting portion. Portions along the periphery of the notches 11d 'and 11e' of 11d and 11e are inserted so as to be relatively movable along the longitudinal direction of the column.
A plurality of through holes are formed in portions of the support portions 11d and 11e along the periphery of the notches 11d 'and 11e'. Through holes communicating with the through holes are formed in the connecting members 20 and 21, and resin holes are formed in both the through holes. 61 are filled. Further, the screw shaft 40 implanted in the vehicle body side member 45 is inserted into the bolt through hole 35 of the connecting members 20 and 21, and the nut 41 screwed to the screw shaft 40 and the vehicle body side member 45 connect the connecting member 20. , 21 are sandwiched. The bolt holes 35 are elongated in the column axis direction in the longitudinal direction, and can cope with positional deviation between members due to manufacturing errors.
As a result, when the resin 61 is sheared at the time of the impact, the upper bracket 11 and the connecting members 20 and 21 relatively move along the longitudinal direction of the column. When the relative movement distance increases, the upper bracket 11 comes out of the connecting members 20 and 21, and the connection between the first column 2a and the vehicle body side member 45 via the upper bracket 11 is released.
[0022]
As shown in FIGS. 1 and 6, the second column 2 b side is attached to a vehicle body side member 45 via a lower bracket 46. The lower bracket 46 is formed of a single steel plate, and includes a first plate-shaped portion 46a disposed at a right angle to the column axis direction, a second plate-shaped portion 46b disposed at an angle to the column axis direction, It has a third plate-like portion 46c and a fourth plate-like portion 46d arranged in parallel to the column axis direction. The first plate portion 46a is connected to the sensor housing 71 by bolts.
Notches 47c and 47d having the steering wheel side opened are formed in the third plate-like portion 46c and the fourth plate-like portion 46d, and the screw shaft 55 implanted in the vehicle body side member 45 is formed in each of the notches 47c and 47d. It is inserted. The third plate-like portion 46c and the fourth plate-like portion 46d are sandwiched between the nut 56 screwed to the screw shaft 55 and the vehicle body side member 45.
[0023]
In the above configuration, when the vehicle collides with an obstacle in front of the vehicle (primary collision) and then the driver of the vehicle collides with the steering wheel (secondary collision), the impact energy is absorbed as follows. Is done.
First, the resin 60 connecting the first handle shaft 5 and the second handle shaft 7 is sheared, and the resin 61 connecting the upper bracket 11 and the connecting members 20 and 21 is sheared. The shear energy absorbs impact energy. You.
Next, the upper bracket 11 moves relative to the connecting members 20 and 21, the first column 2a moves relative to the second column 2b, and the impact energy is absorbed by friction between the relative moving members.
Next, as shown in FIG. 9, the connection between the upper bracket 11 and the vehicle body-side member 45 is released, and the lower bracket 46 is plastically deformed, and the plastic deformation absorbs impact energy.
[0024]
According to the above configuration, the outer periphery of the second column 2b is supported by the inner periphery of the sensor housing 71, and the outer periphery of the third handle shaft 73 is supported by the inner periphery of the second column 2b via the bush 94. The second column 2b can be inserted into the sensor housing 71 up to a position where the second column 2b overlaps the bush 94. On the other hand, if the inner periphery of the second column 103 is supported by the outer periphery of the housing 105a of the torque sensor 105 as in the related art, the second column 103 and the bearing 110 supporting the handle shaft 104c are axially displaced. They will be placed apart. That is, the second column 2b and the bush 94 overlap according to the above-described configuration, compared to the case where the second column 103 and the bearing 110 that are separated in the axial direction are individually supported by the housing 105a as in the related art. Can be shortened in the axial direction. Since the axial dimension of the sensor housing 71 can be shortened, the distance L 'until the first column 2a collides with the sensor housing 71 is increased even if the size of the vehicle body is limited, and the first column 2a and the second column The amount of impact energy absorption is increased by increasing the amount of relative movement with respect to the axis 2b in the axial direction, and the assembly and processing are simplified, and the cost can be reduced.
[0025]
The bush 94 has a split groove 94a and can be elastically expanded and reduced in the radial direction, so that the bush 94 can be easily fitted into the peripheral groove 73a on the outer periphery of the third handle shaft 73. By simply inserting the protruding portion 94b of the bush 94 into the inner periphery of the first detection ring 81, the bush 94 can be held in a state of being reduced in the radial direction, so that the assembling work is facilitated. The movement of the first detection ring 81 in one axial direction is prevented by the one end surface 73a 'of the circumferential groove 73a via the bush 94, whereby the first detection ring 81 is moved in the axial direction with respect to the third handle shaft 73. Relative to each other, which also facilitates the assembly operation. Further, the third handle shaft 73 is supported by the bush 94 instead of the conventional bearing 110, so that the cost can be reduced.
[0026]
The present invention is not limited to the above embodiment. For example, the torque sensor 105 shown in the conventional example may be used in place of the torque sensor of the above embodiment, and the protrusion of the bush may be inserted into the inner periphery of the third detection ring 118. Further, a needle bearing may be used instead of the bush as the support member.
[Brief description of the drawings]
1 is a cross-sectional view of a steering device according to an embodiment of the present invention; FIG. 2 is a partial cross-sectional view of the steering device; FIG. 3 is a cross-sectional view of main components of the steering device; (1) is a front view, (2) is a sectional view [FIG. 5] A partial sectional view of the steering device [FIG. 6] A plan view of the steering device [FIG. 7] A sectional view taken along line VII-VII of FIG. 8 is a sectional view taken along line VIII-VIII in FIG. 5 FIG. 9 is a side view of the steering device after collision FIG. 10 is a sectional view of a conventional steering device FIG. 11 is a circuit diagram of a conventional torque sensor Explanation of reference numerals ]
2a first column 2b second column 70 torque sensor 71 sensor housing 73 third handle shaft 73a circumferential groove 81 first detection ring 94 bush (support member)
94a Split groove 94b Projection

Claims (2)

A first column, a second column inserted into the first column so as to move axially relative to each other when an impact is applied, a handle shaft inserted into both columns, and a torque sensor for detecting a transmission torque by the handle shaft. In the shock-absorbing power steering apparatus for applying a steering assist force corresponding to the detected torque, the outer periphery of the second column is supported by the inner periphery of the housing of the torque sensor, and the inner periphery of the second column is provided. , The outer periphery of the handle shaft is supported via a support member. The torque sensor has a detection ring fitted to the handle shaft, the support member has a split groove, and is a bush that can be elastically expanded and reduced in the radial direction, and the bush is provided on the outer periphery of the handle shaft. The bush is reduced in the radial direction by being fitted into the formed circumferential groove and forming a protrusion extending in the axial direction at one end of the bush, and the protrusion being inserted into the inner periphery of the detection ring. The shock-absorbing power steering apparatus according to claim 1, wherein the detection ring is held in a state of being moved, and movement of the detection ring in one axial direction is prevented by one end surface of the circumferential groove through the bush.

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