JP2006168416A - Strut type front suspension device of front wheel driving vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To preclude giving a sense of incongruity to a driver in conducting a steering operation by suppressing the transient torque steering at starting a vehicle. <P>SOLUTION: If a torque round a coil shaft is caused by elongation of a left and a right coil spring 46 when the vehicle is started, a friction force variable supporting means 56 transmits the torque round the coil shaft as torques round a left and a right steering shaft while high friction bearings 64 and 66 are engaged with an upper support 54 installed at the tops of the coil springs 46 for restricting the rotation. The torques round the left and right steering shafts set off the torque steering willing to be generated on the left and right wheels owing to different length between the left and right driving shafts. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a strut type front suspension device for a front-wheel drive vehicle in which a differential device connected to a drive source is disposed offset from the center in the vehicle width direction.

  For example, a front-wheel drive vehicle (FF vehicle) equipped with a horizontally mounted engine has a differential connected to the engine offset from the center in the vehicle width direction, so the differential and the left and right wheels are connected. The lengths of the left and right drive shafts are different. Since the drive torque transmitted from the left and right drive shafts having different lengths to the left and right wheels has a left-right difference, torque steer is generated. In particular, a large torque steer occurs immediately after the vehicle starts. Here, torque steer is a phenomenon in which steering is taken against the will of the driver.

  The mechanism of torque steer when starting a vehicle is that a secondary couple is generated immediately after the start due to the difference in the outer bending angle of the left and right drive shafts, which generates an unbalanced torque around the left and right kingpin shafts (hereinafter, , Referred to as steady torque steer). Also, just after the start, a left-right difference occurs in the drive torque due to the difference in torsional rigidity of the left and right drive shafts of different lengths, and the product of the left-right difference in drive torque and the kingpin offset It is generated as a balanced torque (hereinafter referred to as transient torque steer). Therefore, immediately after the start of the vehicle, a large torque steer is generated by adding the transient torque steer and the steady torque steer, and the driver feels uncomfortable.

Here, as a conventional technique for reducing torque steer, for example, the left and right kingpin shafts are different by causing the arm span of the suspension arm to be different on the left and right, causing a difference in the steering angle of the left and right wheels due to the driving reaction force during vehicle acceleration. A technique for reducing the torque steer by canceling the difference in steering angle between the left and right wheels based on the torque generated around the wheel (for example, Patent Document 1), and the height position of the coupling point between the knuckle arm and the tie rod are made different on the left and right. A technology that reduces torque steer by causing different toe changes in the left and right wheels due to the power hop phenomenon during vehicle acceleration, and canceling the difference in the steering angle between the left and right wheels based on the torque generated around the left and right kingpin shafts ( For example, Patent Document 2) is known.
Japanese Utility Model Publication No. 61-9766 Japanese Utility Model Publication No. 61-23450

However, since the conventional techniques of Patent Documents 1 and 2 reduce the torque steer in proportion to the acceleration of the vehicle, the transient torque steer that occurs only when the vehicle starts cannot be suppressed, and the driver Will give a strange feeling to the steering operation.
The present invention has been made in order to eliminate such inconveniences, and by suppressing the transient torque steer when the vehicle starts, the front-wheel drive vehicle capable of preventing a driver from feeling uncomfortable with the steering operation. An object of the present invention is to provide a strut type front suspension device.

  In order to solve the above-described problems, a strut type front suspension device for a front wheel drive vehicle according to the present invention is a front wheel drive vehicle in which a differential device connected to a drive source is disposed offset from the center in the vehicle width direction. The left and right drive shafts extending in the vehicle width direction with different lengths are connected to the left and right front wheels, respectively, and the left and right wheel support members and the vehicle body that are rotatable around the steering shaft together with the left and right front wheels. In a strut-type front suspension device for a front-wheel drive vehicle in which left and right coil springs are disposed between side members, the lower end portions of the left and right coil springs are supported so as not to rotate relative to the left and right wheel support members. In addition, between the upper end portions of the left and right coil springs and the vehicle body side member, the support friction between the upper end portions of the left and right coil springs and the vehicle body side member. Friction force variable support means for supporting the upper end portion with variable force is arranged, and the friction force variable support means is a rotational force around the coil axis generated by extension of the left and right coil springs when the vehicle starts. Is transmitted as torque around the left and right turning shafts by enlarging the support friction force and restricting the rotation of the upper end portions of the left and right coil springs. The left and right coil springs are arranged so that the left and right drive shafts are different in length at the time of start so that the left and right front wheels generate torque in the opposite direction.

  According to the strut type front suspension device for a front wheel drive vehicle of the present invention, the frictional force variable support means increases the supporting frictional force when the vehicle starts, and the frictional force variable supporting means increases the rotational force around the coil axis generated by the extension of the left and right coil springs. By restricting the rotation of the upper ends of the left and right coil springs, it is transmitted as torque around the left and right turning shafts, and the torque around the left and right turning shafts is the length of the left and right drive shafts when the vehicle starts. Since the torque steer that is about to occur on the left and right front wheels is canceled by the difference, the driver's steering operation does not feel uncomfortable.

Hereinafter, a strut type front suspension device for a front wheel drive vehicle according to the present invention will be described with reference to the drawings.
1 is a diagram showing a front-wheel drive vehicle equipped with a horizontally mounted engine from the rear of the vehicle, FIG. 2 is a diagram showing the front-wheel drive vehicle in plan view, and FIG. 3 is a diagram showing a configuration of a strut type front suspension. 4 to 7 are diagrams showing the frictional force variable support part of the first embodiment according to the present invention, FIGS. 8 to 10 are diagrams showing the frictional force variable support part of the second embodiment according to the present invention, and FIG. 11 is a diagram showing a frictional force variable support portion according to the third embodiment of the present invention.

As shown in FIG. 1, the horizontal engine 2 mounted on the front of the vehicle body has a crankshaft extending in the vehicle width direction, and a differential 6 is connected to the left side of the engine 2 via a transmission 4. Yes. The engine 2 and the transmission 4 correspond to the drive source of the present invention.
A left drive shaft 8 is connected to the left side of the differential 6 and a left front wheel 10 _L is connected to the left drive shaft 8 through a constant velocity joint 9a. A right drive shaft 16 is connected to the right side of the differential device 6 via an intermediate shaft 14 extending in the vehicle width direction, and a right front wheel 10 _R is connected to the right drive shaft 16 via a constant velocity joint 9b. Yes.

Next, FIG. 3 is a diagram showing a strut type front suspension for supporting a left front wheel 10 _L. The strut type front suspension that supports the right front wheel 10 _R has the same configuration although the arrangement position in the vehicle width direction is opposite to that in FIG.
This suspension includes a wheel support member 20 formed with a cylindrical portion 20 d for inserting and supporting the left drive shaft 8 of the left front wheel 10 _L. A lower link 24 is connected to a lower end portion 20 a of the wheel support member 20 via a ball joint 22. The upper link 28 and the strut 30 are connected via a connecting portion 26 provided on the upper end portion 20b, and the tie rod 32 is connected to a support portion 20c that protrudes and extends rearward at the center portion. The tie rod 32 is connected to a steering device 33 shown in FIG.

The lower link 24 is disposed so as to extend in the vehicle width direction, the inner end is bifurcated, and each end is connected to the vehicle body side member 50 via the elastic body bush 25. The upper link 28 is configured by a single I-type link, and an inner end in the vehicle width direction of one end is coupled to the vehicle body side member 50. Connecting portion 26, the upper end portion 20b of the wheel support member 20 is provided to match the axis on an extension line of the kingpin axis L _K passing through the center of the ball joint 22 of the lower end.

The strut 30 includes a shock absorber 44 extending in the vehicle vertical direction and a coil spring 46 disposed coaxially therearound.
The lower end of the cylinder tube 44a constituting the shock absorber 44 is connected to the connecting portion 26 via the mounting bracket 48, and the upper end portion of the piston rod 44b protruding upward from the cylinder tube 44a is connected to the vehicle body side member 50. It is connected to a fixed friction force variable support portion 56 which will be described later.

  The coil spring 46 uses a left-handed coil spring that spirally extends counterclockwise when viewed from the lower end, and the lower end is supported by a lower seat 52 that is fixed to the outer periphery of the cylinder tube 44a by welding. The upper end portion of the upper support 54 is supported by the upper support 54, and the upper support 54 is supported by the frictional force variable support portion 56. Here, the upper and lower end portions of the coil spring 46 have a structure in which the frictional force at the contact portion between the lower seat 52 and the upper support 54 is increased so that they do not rotate relative to each other.

  Here, the coil spring 46 generates torque around the coil axis when compressed or expanded. Then, the coil spring 46 set to be counterclockwise as in the present embodiment generates counterclockwise torque when viewed from the lower end when extending, and clockwise torque when viewed from the lower end when compressing. appear. The upper support 54 supporting the upper end portion of the coil spring 46 rotates with the compression or extension of the coil spring 46.

The frictional force variable support portion 56 is a member that supports the upper support 54 by changing the engagement frictional force with the vehicle body side member 50.
As shown in FIG. 4, a disc-shaped locking plate 44c is attached to the upper end of the piston rod 44b. The upper support 54 has a shape in which a disc-shaped flange portion 54c is integrated with an inner diameter portion of a spring support portion 54a that supports an upper end portion of the coil spring 46 via a cylindrical portion 54b.

Then, the upper end side of the piston rod 44b and the cylindrical portion 54b of the upper support 54 are loosely inserted into the case 56a of the frictional force variable support portion 56 fixed to the vehicle body side member 50, and the locking plate 44c and the flange portion 54c are moved up and down. They are arranged in parallel. The locking plate 44 c is connected to the upper portion of the inner wall of the frictional force variable support portion 56 via the insulator 58.
An annular first resin bearing 60 is disposed on the outer peripheral side upper surface of the flange portion 54 c, and the first resin bearing 60 is in contact with the upper part of the inner wall of the case 56 a via an annular disc spring 62. An annular second resin bearing 64 is disposed on the inner peripheral upper surface of the flange portion 54c in proximity to the lower surface of the locking plate 44c. Further, an annular third resin bearing 66 is disposed in the lower part of the inner wall of the case 56a in the vicinity of the lower surface of the flange portion 54c.

  The first to third resin bearings 60, 64 and 66 are bearings in which an annular resin plate is interposed between two annular plates, and a predetermined frictional force is generated during rotation. As for the magnitude of the frictional force, the frictional force f2 of the second resin bearing 64 is the largest, then the frictional force f3 of the third resin bearing 66 is the largest, and the frictional force f1 of the first resin bearing 60 is the smallest. (F2> f3> f1).

Next, a mechanism for generating torque steer when the vehicle starts by disposing the differential device 6 offset from the center in the vehicle width direction will be described.
As shown in FIG. 1, since the differential device 6 is disposed offset to the left side in the vehicle width direction, a large torque steer obtained by adding the transient torque steer and the steady torque steer is generated immediately after the start of the vehicle. And That is, steady torque steer is generated by the secondary couple generated by the difference between the bending angles θ _L and θ _R of the left drive shaft 8 and the right drive shaft 16 from the start. Further, driving torque only immediately after starting, the torsional rigidity of the left drive shaft 8 which have different length, higher than the torsional rigidity of the intermediate shaft 14 and the right drive shaft 16 is transmitted to the front left wheel 10 _L Becomes larger than the driving torque transmitted to the right front wheel 10 _R , and transient torque steer occurs.
Therefore, immediately after the start, as shown in FIG. 2, the kingpin axis L _K around the torque T _L of the left front wheel 10 _L becomes larger than the kingpin axis L _K around the torque T _R of the front right wheel 10 _R, steering Torque steer is about to occur that tries to rotate the to the right.

Next, the operation of the frictional force variable support portion 56 that accompanies constant speed traveling and decelerating traveling when the vehicle starts will be described with reference to FIGS.
When the vehicle travels at a constant speed, as shown in FIG. 4, the left and right coil springs 46 are repeatedly expanded and compressed with a small stroke. The first resin bearing 60 of the frictional force variable support portion 56 supports the flange portion 54c of the upper support 54 via the disc spring 62, the second resin bearing 64 is separated from the locking plate 44c, and the third resin bearing 66 is supported. Is also separated from the flange portion 54c. Thereby, the frictional force variable support portion 56 supports the upper support 54 via the first resin bearing 60 that generates a small frictional force f1.

  The left and right coil springs 46 that repeatedly expand and compress with a small stroke generate torque around the coil axis, but the first resin bearing 60 with a small frictional force f1 supports the upper support 54 in a freely rotatable manner. The torque around the coil axis of the left and right coil springs 46 is not transmitted to the left and right wheel support members 20 side.

  Further, immediately after the start of the vehicle, as shown in FIG. 5, the left and right coil springs 46 extend with a large stroke as the vehicle front lifts up. Since the shock absorber 44 generates a damping force that suppresses lift-up of the front portion of the vehicle, the locking plate 44c attached to the piston rod 44b moves downward relative to the vehicle body side member 50. When the locking plate 44c moves downward, the second resin bearing 64 comes into contact with the lower surface of the locking plate 44c, and the third resin bearing 66 comes into contact with the lower surface of the flange portion 54c of the upper support 54. The disc spring 62 applies a load to the first resin bearing 60 from above. As described above, immediately after the vehicle starts, the frictional force variable support portion 56 supports the upper support 54 via the first resin bearing 60, the second resin bearing 64, and the third resin bearing 66.

The left and right coil springs 46 extended with a large stroke immediately after the start of the vehicle generate torque around the coil axis counterclockwise when viewed from the upper end. The frictional force variable support portion 56 rotates the flange portion 54c of the upper support 54 with a large support friction force (f1 + f2 + f3) obtained by combining the friction forces of the first resin bearing 60, the second resin bearing 64, and the third resin bearing 66. since the regulating, in a state where the rotation of the flange portion 54c is restricted, the coil axis of the torque of the left and right of the coil spring 46, the front left wheel 10 _L kingpin axis L _K around the torque T _S, the front right wheel It is transmitted to the left and right wheel support members 20 as a torque T _S around the 10 _R kingpin axis L _K.

Thus, the coil axis of the torque left and right coil springs 46 occurs to extend in a large stroke, the left front wheel 10 _L kingpin axis L _K around the torque T _S, the front right wheel 10 _R kingpin axis L _K around Once transmitted to the left and right wheel support member 20 as the torque T _S, as shown in FIG. 2, acts in a direction to cancel the kingpin axis L _K around the torque T _L of the left front wheel 10 _L which is a cause of torque steer Therefore, a large torque steer that is to be generated immediately after starting, that is, a large torque steer that combines the transient torque steer and the steady torque steer is suppressed.

  Further, when a predetermined time elapses (for example, after 1 or 2 seconds) immediately after the start and the damping force of the shock absorber 44 is reduced but the front portion of the vehicle is lifted up, as shown in FIG. The second resin bearing 64 is separated from the lower surface of the upper support 54, and the third resin bearing 66 is in contact with the lower surface of the flange portion 54 c of the upper support 54. At this time, the frictional force variable support portion 56 supports the upper support 54 via the first resin bearing 60 and the third resin bearing 66.

The frictional force variable support portion 56 regulates the rotation of the flange portion 54c of the upper support 54 with a relatively large support frictional force (f1 + f3) obtained by combining the frictional forces of the first resin bearing 60 and the third resin bearing 66. because there, in the state where the rotation of the flange portion 54c is restricted, the coil axis of the torque of the left and right coil springs 46, the kingpin axis L _K around the torque T _S of the left front wheel _{10 L '(T S> T} S '), And is transmitted to the left and right wheel support members 20 as torque T _S ' (T _S > T _S ') around the kingpin axis L _K of the right front wheel 10 _R.
The left front wheel 10 _L kingpin axis L _K around the torque T _S of the 'right front wheels 10 _R kingpin axis L _K around the torque T _S of' is transmitted to the left and right wheel support members 20, predetermined immediately after the start time Steady torque steer when it has elapsed is suppressed.

  Further, when the vehicle decelerates, as shown in FIG. 7, the left and right coil springs 46 are compressed with a large stroke as the vehicle front is lifted down. Since the shock absorber 44 generates a damping force that suppresses lift-down of the front portion of the vehicle, the locking plate 44c attached to the piston rod 44b moves upward relative to the vehicle body side member 50, and the vehicle body side member With 50, the frictional force variable support portion 56 moves downward. Thus, a vehicle body load is applied to the first resin bearing 60 from above while the disc spring 62 is in a crushed state, the second resin bearing 64 is separated from the locking plate 44c, and the third resin bearing 66 is also separated from the flange portion 54c. It is in a separated state. That is, the frictional force variable support portion 56 supports the upper support 54 via the first resin bearing 60 when the vehicle decelerates.

The left and right coil springs 46 that compress with a large stroke generate torque around the coil axis, but the first resin bearing 60 supports the upper support 54 while rotating it, so that the coil spring 46 rotates around the coil axis. Torque is hardly transmitted to the left and right wheel support members 20 side.
Therefore, in the present embodiment, when the left and right coil springs 46 are extended and a torque around the coil axis is generated when the vehicle starts, the frictional force variable support portion 56 restricts the rotation of the upper support 54 with a large support frictional force. and, in a state where the rotation of the upper support 54 is restricted, the coil axis of the torque of the left and right coil springs 46, the kingpin axis L _K around the torque of the left front wheel 10 _L, kingpin axis L _K of the front right wheel 10 _R is transmitted to the left and right wheel support member 20 as the torque around, so it acts in a direction to cancel the kingpin axis L _K around the torque of the left front wheel 10 _L which is a factor of the torque steer to rotate the steering in one left and right Therefore, it is possible to prevent fluctuations in the steering holding force by suppressing the torque steer that is generated when the vehicle starts. Never give an uncomfortable feeling to the ring operation.

Further, when the vehicle is traveling at a constant speed or when the vehicle is decelerating, the friction variable support portion 56 supports the upper support 54 with a small supporting frictional force so that the upper support 54 is rotatable with respect to the vehicle body side member 50. The torque around the coil axis generated by the left and right coil springs 46 is hardly transmitted as the torque around the kingpin axis L _{K of} the left and right front wheels 10 _L , 10 _R. The running stability of the car is not affected.

  Also. The variable friction support portion 56 includes a first resin bearing 60 having a small frictional force, and a second resin bearing 64 and a third resin bearing 66 having a frictional force larger than that of the first resin bearing 60. At the time of starting, the upper support 54 is supported by the support friction force generated by the first resin bearing 60, the second resin bearing 64, and the third resin bearing 66, so that the torque around the coil axis generated by the left and right coil springs 46 is increased. Can be reliably transmitted in a direction to cancel the torque that causes torque steer, and when the vehicle travels at a constant speed or the vehicle travels at a reduced speed, the first resin bearing 60 generates a small support friction force. Since the upper support 54 is rotatably supported, the coil support around the coil axis generated by the left and right coil springs 46 Torque can be prevented from being transmitted to the left and right wheel support member 20 side.

Further, the second resin bearing 64 (friction force f2) is a bearing having a larger friction force than the third resin bearing 66 (friction force f3) (f2> f3), and the first resin bearing 60 immediately after the vehicle starts. By supporting the upper support 54 with a large supporting friction force by the second resin bearing 64 and the third resin bearing 66, a large torque steer combined with the transient torque steer and the steady torque steer that is to be generated immediately after starting is ensured. When a predetermined time elapses (for example, after 1 or 2 seconds) immediately after starting, the first resin bearing 60 and the third resin bearing 66 reduce the support friction force (relatively large support) immediately after starting. This occurs when a predetermined time elapses immediately after starting by supporting the upper support 54 with a friction force). The steady-state torque steer and can be reliably suppressed.
In addition, since the first to third resin bearings 60, 64, 66 are thin bearings, the friction variable support portion 56 can be reduced in size, and the friction variable support can be performed while increasing the degree of freedom of layout in a narrow space above the suspension. The part 56 can be arranged.

Next, with reference to FIGS. 8 to 10, the frictional force variable support portion 70 of the second embodiment will be described. The same components as those shown in FIGS. 1 to 7 are denoted by the same reference numerals and description thereof is omitted.
In the present embodiment, the upper support 54 has a cylindrical portion 54d formed integrally with the inner diameter portion of the spring support portion 54a, and this cylindrical portion 54d is disposed in the case 70a of the frictional force variable support portion 70. ing.
In addition, an annular first resin bearing 60 is interposed between the upper surface of the spring support portion 54a and the lower surface of the case 70a, and an annular second portion is provided on the upper surface of the cylindrical portion 54d in proximity to the lower surface of the locking plate 44c. A resin bearing 64 is disposed.

As in the first embodiment, the first resin bearing 60 and the second resin bearing 64 are set such that the friction force f2 of the second resin bearing 64 is large and the friction force f1 of the first resin bearing 60 is small (f2). > F1).
The coil spring 46 is also a left-handed coil spring. When the coil spring 46 is extended, the lower end portion generates a counterclockwise torque. When the coil spring 46 is compressed, the lower end portion generates a clockwise torque.

Next, the operation of the frictional force variable support portion 70 according to the present embodiment accompanying the constant speed traveling and the decelerating traveling when the vehicle is started will be described with reference to FIGS. 8 to 10.
When the vehicle travels at a constant speed, as shown in FIG. 8, the left and right coil springs 46 repeatedly extend and compress with a small stroke. The first resin bearing 60 of the frictional force variable support portion 70 supports the spring support portion 54a of the upper support 54, and the second resin bearing 64 is separated from the locking plate 44c. Thereby, the frictional force variable support portion 70 supports the upper support 54 via the first resin bearing 60 that generates a small frictional force.

  The left and right coil springs 46 repeatedly extending and compressing with a small stroke generate torque around the coil axis, but the first resin bearing 60 rotatably supports the spring support portion 54a of the upper support 54 with a small support frictional force. Therefore, the torque around the coil axis of the left and right coil springs 46 is hardly transmitted to the left and right wheel support members 20 side.

  Immediately after starting the vehicle, as shown in FIG. 9, the left and right coil springs 46 extend with a large stroke as the vehicle front lifts up. Since the shock absorber 44 generates a damping force that suppresses lift-up of the front portion of the vehicle, the locking plate 44c attached to the piston rod 44b moves downward relative to the vehicle body side member 50. When the locking plate 44c moves downward, the second resin bearing 64 comes into contact with the lower surface of the locking plate 44c. As described above, immediately after the vehicle starts, the frictional force variable support unit 70 supports the upper support 54 via the first resin bearing 60 and the second resin bearing 64.

The left and right coil springs 46 extended with a large stroke immediately after the start of the vehicle generate torque around the coil axis counterclockwise when viewed from the upper end. Since the frictional force variable support portion 56 restricts the rotation of the upper support 54 with a large support frictional force (f1 + f2) obtained by combining the frictional forces of the first resin bearing 60 and the second resin bearing 64, the upper support 54 in the state where the rotation of which is restricted, the coil axis of the torque of the left and right of the coil spring 46, the front left wheel 10 _L kingpin axis L _K around the torque T _S for ", the front right wheel 10 _R kingpin axis L _K around The torque T _S ″ is transmitted to the left and right wheel support members 20.

Thus, the coil axis of the torque left and right coil springs 46 occurs to extend in a large stroke, kingpin axis L _K around the torque T _S of the left front wheel 10 _L ", the front right wheel 10 _R kingpin axis L _K around Once transmitted to the left and right wheel support member 20 as the torque T _S ", shown in Figure 2, the direction of canceling the kingpin axis L _K around the torque T _L of the left front wheel 10 _L which is a cause of torque steer Therefore, a large torque steer that is to be generated immediately after starting, in particular, a transient torque steer is suppressed.

  Further, when the vehicle decelerates, as shown in FIG. 10, the left and right coil springs 46 are compressed with a large stroke as the vehicle front is lifted down. Since the shock absorber 44 generates a damping force that suppresses lift-down of the front portion of the vehicle, the locking plate 44c attached to the piston rod 44b moves upward relative to the vehicle body side member 50, and the vehicle body side member 50 and the frictional force variable support portion 70 move downward. Thereby, a vehicle body load is applied to the first resin bearing 60 from above, and the second resin bearing 64 is separated from the locking plate 44c. That is, when the vehicle is decelerating, the frictional force variable support portion 70 supports the upper support 54 via the first resin bearing 60.

  The left and right coil springs 46 that compress with a large stroke generate torque around the coil axis, but the first resin bearing 60 supports the upper support 54 while rotating it with a small support frictional force, so that the coil spring 46 is supported. The torque around the coil axis is hardly transmitted to the left and right wheel support members 20 side.

Therefore, in the present embodiment, when the left and right coil springs 46 are extended and a torque around the coil axis is generated when the vehicle starts, the frictional force variable support portion 70 rotates the upper support 54 with a large support frictional force. regulation and, in the state in which rotation of the upper support 54 is restricted, the coil axis of the torque of the left and right coil springs 46, the kingpin axis L _K around the torque of the left front wheel 10 _L, kingpin axis L of the front right wheel 10 _R is transmitted to the _K around the left and right wheel support member 20 as a torque, which acts in a direction to cancel the front left wheel 10 _L kingpin axis L _K around torque which causes the torque steer to rotate the steering in one left and right Therefore, it is possible to suppress the torque steer that occurs when the vehicle starts and to prevent fluctuations in the steering holding force. Never give an uncomfortable feeling to the ring operation.

In addition, when the vehicle is traveling at a constant speed or when the vehicle is decelerating, the friction variable support unit 70 supports the upper support 54 with a small support frictional force so that the upper support 54 is rotatable with respect to the vehicle body side member 50. Torque around the coil axis generated by the left and right coil springs 46 is not transmitted as torque around the kingpin axis L _{K of} the left and right front wheels 10 _L , 10 _R , and traveling stability at constant speed traveling, Does not affect the running stability.

Also. The friction variable support portion 70 includes a first resin bearing 60 having a small frictional force and a second resin bearing 64 having a frictional force larger than that of the first resin bearing 60. When the vehicle is started, the first resin bearing 60 is provided. Further, by supporting the upper support 54 with the support friction force generated by the second resin bearing 64, the torque around the coil axis generated by the left and right coil springs 46 can be surely canceled in the direction to cancel the torque that causes torque steer. Since the upper support 54 is rotatably supported by a small engagement friction force generated by the first resin bearing 60 when the vehicle can travel at a constant speed or when the vehicle decelerates, the left and right coils The torque around the coil axis generated by the spring 46 is prevented from being transmitted to the left and right wheel support members 20 side. It is possible.
In addition, since the first and second resin bearings 60 and 64 are thin bearings, the friction variable support portion 70 can be reduced in size, and the degree of freedom in layout can be increased in a narrow space above the suspension while the variable friction support portion 70 is increased. Can be arranged.

Next, with reference to FIG. 11, the frictional force variable support part 80 of 3rd Embodiment is demonstrated. In the present embodiment, the same components as those shown in FIGS. 1 to 7 are denoted by the same reference numerals, and description thereof is omitted.
In the present embodiment, an annular electrorheological fluid (hereinafter referred to as ER fluid) sealed bearing 84, an ER fluid sealed bearing 84, and a case 82 interposed between the upper surface of the spring support portion 54 a and the lower surface of the case 82. A voltage supply unit 86 that applies a voltage having a predetermined strength and a voltage controller 90 that controls the voltage supply unit 86 based on input information of an acceleration sensor 88 mounted on the vehicle are provided.

  The ER fluid-sealed bearing 84 is a bearing in which ER fluid is sealed between two annular plate members 84a and 84b arranged on the upper and lower sides, and from the voltage supply unit 86 to the one annular plate member 84a via the case 82, the other one at the same time. When a voltage having a predetermined strength is applied to the annular plate member 84b, the viscosity of the ER fluid is changed, and the rotational friction force when the annular plate members 84a and 84b rotate relative to each other changes.

The voltage controller 90 includes a microcomputer, necessary interface circuits, an A / D converter, a D / A converter, and the like. Based on input information from the acceleration sensor 88, the voltage controller 90 The state of the constant speed traveling and the decelerating traveling of the vehicle is determined, and a voltage control signal is output to the voltage supply unit 86 according to the traveling state.
The coil spring 46 of the present embodiment is also a left-handed coil spring, which generates a counterclockwise torque at the lower end when it is extended, and a clockwise torque at the lower end when it is compressed. appear.

Next, operation | movement of the frictional force variable support part 80 of this embodiment is demonstrated.
When the vehicle travels at a constant speed, the voltage controller 90 does not perform voltage control on the voltage supply unit 86.
The left and right coil springs 46 that repeatedly extend and compress with a small stroke generate torque around the coil axis, but the ER fluid-filled bearing 84 to which no voltage is applied from the voltage supply unit 86 has a low ER fluid viscosity, and the annular plate material. The rotational friction force at the time of relative rotation of 84a and 84b is reduced, and the spring support portion 54a of the upper support 54 is rotatably supported with a small support friction force. Thereby, the torque around the coil axis of the left and right coil springs 46 is hardly transmitted to the left and right wheel support member 20 side.

  Moreover, immediately after the vehicle starts, the voltage controller 90 that calculates a predetermined acceleration gradient based on input information from the acceleration sensor 88 controls the voltage supply unit 86 so that a predetermined strong voltage is applied. The ER fluid sealed bearing 84 to which a strong voltage is applied from the voltage supply unit 86 has a high viscosity of the ER fluid, and a rotational frictional force during the relative rotation of the annular plate members 84a and 84b increases.

The left and right coil springs 46 extended with a large stroke immediately after the start of the vehicle generate torque around the coil axis counterclockwise when viewed from the upper end. Since the viscosity of the ER fluid is increased in the ER fluid sealed bearing 84 and the rotation of the upper support 54 is restricted by a large support friction force, the rotation of the upper support 54 is restricted in the state where the rotation of the left and right coil springs 46 is restricted. Torque around the coil axis is transmitted to the left and right wheel support members 20 as torque T _S around the kingpin axis L _{K of} the left front wheel 10 _L and torque T _S around the king pin axis L _{K of} the right front wheel 10 _R.

Thus, the coil axis of the torque left and right coil springs 46 occurs to extend in a large stroke, the left front wheel 10 _L kingpin axis L _K around the torque T _S, the front right wheel 10 _R kingpin axis L _K around When the torque T _S is transmitted to the left and right wheel support members 20, it acts in a direction to cancel the torque T _L around the kingpin axis L _K of the left front wheel 10 _L , which is a factor of torque steer. The transient torque steer to be attempted is suppressed.

  Further, when a predetermined time elapses immediately after the start (for example, after 1 or 2 seconds), the voltage controller 90 that calculates the predetermined acceleration based on the input information from the acceleration sensor 88 applies a voltage slightly lower than the strong voltage immediately after the start. Thus, the voltage supply unit 86 is controlled. The ER fluid-sealed bearing 84 to which the above-described voltage is applied from the voltage supply unit 86 increases the viscosity of the ER fluid, and the rotational friction force during the relative rotation of the annular plate members 84a and 84b increases.

As a result, when a predetermined time has passed immediately after starting, the rotation of the upper support 54 is regulated with a slightly lower force than just after starting, and the coil shafts of the left and right coil springs 46 are controlled in a state where the rotation of the upper support 54 is regulated. The turning torque is transmitted to the left and right wheel support members 20 as torque T _S 'around the kingpin axis L _K of the left front wheel 10 _L and torque T _S ' around the king pin axis L _{K of} the right front wheel 10 _R.

The left front wheel 10 _L kingpin axis L _K around the torque T _S of the 'right front wheels 10 _R kingpin axis L _K around the torque T _S of' is transmitted to the left and right wheel support members 20, predetermined immediately after the start time Steady torque steer when it has elapsed is suppressed.
Further, when the vehicle is decelerating, the voltage controller 90 does not perform voltage control on the voltage supply unit 86 based on input information from the acceleration sensor 88.

  When the vehicle decelerates, the left and right coil springs 46 are compressed with a large stroke as the vehicle front is lifted down, but the ER fluid sealed bearing 84 to which no voltage is applied from the voltage supply unit 86 has a low ER fluid viscosity. The rotational frictional force at the time of relative rotation of the annular plate members 84a and 84b is reduced, and the spring support portion 54a of the upper support 54 is rotatably supported with a small support frictional force. Is hardly transmitted to the left and right wheel support members 20 side.

Therefore, in the present embodiment, when the left and right coil springs 46 are extended and a torque around the coil axis is generated when the vehicle starts, the voltage controller 90 has a predetermined strong strength based on the input information from the acceleration sensor 88. The voltage supply unit 86 is controlled so that a voltage is applied, and the ER fluid sealed bearing 84 to which a strong voltage is applied from the voltage supply unit 86 has a high viscosity of the ER fluid, and the annular plate members 84a and 84b are at the time of relative rotation. Since the rotational friction force becomes large, the rotation of the upper support 54 is restricted by a large support friction force, and when the rotation of the upper support 54 is restricted, the torque around the coil axis of the left and right coil springs 46 kingpin axis L _K around the torque of the wheel 10 _L, the left and right wheel support members as the kingpin axis L _K torque around the front right wheel 10 _R 0 is transmitted, acts in a direction to cancel the front left wheel 10 _L kingpin axis L _K around torque which causes the torque steer to rotate the steering in one left and right. As a result, the torque steer that is about to occur when the vehicle starts can be suppressed to prevent fluctuations in the steering holding force, and the driver's steering operation does not feel uncomfortable.

  Further, when the vehicle is traveling at a constant speed or when the vehicle is decelerating, the ER fluid sealed bearing 84 to which no voltage is applied from the voltage supply unit 86 has a low viscosity of the ER fluid, and the relative rotation of the annular plate members 84a and 84b. By reducing the rotational friction force, the spring support portion 54a of the upper support 54 is rotatably supported by a small support friction force, so that the torque around the coil axis of the left and right coil springs 46 is the left and right wheel support members 20. Is hardly transmitted to the vehicle side, and does not affect the running stability at a constant speed and the running stability at a reduced speed.

Furthermore, since the ER fluid-filled bearing 84 is a thin-walled bearing, it can be arranged in a narrow space above the suspension while increasing the degree of freedom in layout.
A vehicle to which the strut type front suspension device for a front-wheel drive vehicle of the present invention is applied is an engine if it is a vehicle equipped with a drive source and a differential device that is positioned offset from the center in the vehicle width direction. The present invention can be applied not only to an engine-driven vehicle using a transmission as a drive source, but also to an electric vehicle using a motor and transmission as a drive source, and a hybrid vehicle using an engine and motor as a drive source.

It is the figure which showed the front-wheel drive vehicle carrying a horizontal installation engine from the vehicle front. It is the figure which showed the front-wheel drive vehicle by planar view. It is a figure which shows the structure of a strut type front suspension. FIGS. 4 to 7 show the frictional force variable support part of the first embodiment according to the present invention, and FIGS. 8 to 10 show the frictional force variable support part of the second embodiment of the invention. Furthermore, FIG. 11 is a diagram showing a frictional force variable support portion of a third embodiment according to the present invention. It is a figure which shows the structure of the frictional force variable support means of 1st Embodiment which concerns on this invention. It is a figure which shows operation | movement of the frictional force variable support means of 1st Embodiment immediately after a vehicle starts. It is a figure which shows operation | movement of the frictional force variable support means of 1st Embodiment when 1 second after 1 second passes immediately after starting of a vehicle. It is a figure which shows operation | movement of the frictional force variable support means of 1st Embodiment when the vehicle is decelerating. It is a figure which shows the structure of the frictional force variable support means of 2nd Embodiment which concerns on this invention. It is a figure which shows operation | movement of the frictional force variable support means of 2nd Embodiment immediately after a vehicle starts. It is a figure which shows operation | movement of the frictional force variable support means of 2nd Embodiment when the vehicle is decelerating. It is a figure which shows the structure of the frictional force variable support means of 3rd Embodiment which concerns on this invention.

Explanation of symbols

2 Engine 4 Transmission 6 Differential 8 Left drive shaft 10 _R Right front wheel 10 _L Left front wheel 16 Right drive shaft 20 Wheel support member 30 Strut 44 Shock absorber 44b Piston rod 44c Locking plate 46 Coil spring 50 Car body side member 54 Upper Support 54a Spring support 54c Flange 56a, 70a, 82 Case 56, 70, 80 Friction variable support (friction force variable support means)
60 First resin bearing (first bearing)
62 Second resin bearing (second bearing)
64 Third resin bearing (second bearing)
84a, 84b Annular plate material 84 ER fluid sealed bearing (electrorheological fluid sealed bearing)
86 Voltage supply means 88 Acceleration sensor (detection means)
90 Voltage controller (control means)

Claims (4)

The differential device connected to the drive source is a front wheel drive vehicle arranged offset from the center in the vehicle width direction, and left and right drive shafts extending in the vehicle width direction with different lengths from the differential device are A strut-type front suspension for a front-wheel drive vehicle in which left and right coil springs are arranged between the left and right wheel support members and the vehicle body side member that are connected to the front wheels and are rotatable around the turning shaft together with the left and right front wheels. In the device
The left and right coil springs support lower end portions of the left and right coil springs so as not to rotate relative to the left and right wheel support members, and the left and right coil springs are disposed between the upper end portions of the left and right coil springs and the vehicle body side member. Friction force variable support means for supporting the upper end portion so that the support friction force between the upper end portion and the vehicle body side member is variable is disposed,
The variable frictional force support means is configured to rotate the upper end portions of the left and right coil springs by increasing the rotational friction force around the coil axis generated by the extension of the left and right coil springs when the vehicle starts. Is transmitted as torque around the left and right turning shafts, and the torque around the left and right turning shafts is different between the left and right front wheels because the lengths of the left and right drive shafts are different when the vehicle starts. A strut type front suspension device for a front wheel drive vehicle, wherein the left and right coil springs are arranged so as to be generated in a direction opposite to a generated torque.   An upper support is disposed at the upper end of the coil spring so as not to be relatively rotatable, and the frictional force variable support means includes a first bearing that rotatably supports the upper support on the vehicle body side member, and the left and right coil springs. When the left and right coil springs are free-length or compressed, a support frictional force is generated between the upper support and the vehicle body side member by being sandwiched between the upper support and the vehicle body side member. And a second bearing spaced from at least one of the vehicle body side members, wherein the friction of the second bearing is greater than the friction of the first bearing. Strut type front suspension device.   The strut type front suspension for a front wheel drive vehicle according to claim 2, wherein the first bearing and the second bearing are resin bearings in which an annular resin plate is interposed between two annular plates. apparatus.   An upper support is disposed at the upper end portion of the coil spring so as not to be relatively rotatable, and the frictional force variable support means is interposed between the upper support and the vehicle body side member and is electroviscous between two annular plate members. An electrorheological fluid-enclosed bearing enclosing a fluid, voltage supply means for changing the viscosity of the electrorheological fluid by applying a voltage of a predetermined strength to the electrorheological fluid-enclosed bearing, and detection for detecting the running state of the vehicle 2. A strut type front suspension device for a front wheel drive vehicle according to claim 1, further comprising control means for controlling the voltage supply means based on information from the means.

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