Vehicle suspension apparatus

It is an object to effectively enhance rigidity of a subframe installed to couple a pair of right and left wheel suspension members, with a simple structure, and allow a stabilizer to be adequately installed. A subframe (3) installed to couple a pair of right and left wheel suspension members (2) together comprises a cross member (31) provided with a lateral-link support portion (14, 18) supporting an end of the lateral link (5, 6), a pair of right and left side members (33) each extending from a respective one of opposite vehicle-widthwise outer ends of the cross member (31), in a vehicle longitudinal direction; and a pair of right and left reinforcing members (35) each reinforcing a coupling section between the lateral-link support portion (14, 18) of the cross member (31) or a vicinity thereof, and a respective one of the side members (33). A stabilizer (10) is installed above the cross member (31) to extend in a vehicle widthwise direction in such a manner as to couple the right and left wheel suspension members 2, and each of the reinforcing members (35) is provided with a stabilizer support section torsionably supporting the stabilizer (10).

TECHNICAL FIELD

The present invention relates to a vehicle suspension apparatus which comprises a wheel carrying member adapted to rotatably carry a wheel, a pair of right and left wheel suspension members each including a lateral link having one end mounted to the wheel carrying member, and a subframe installed to couple the right and left wheel suspension members together.

BACKGROUND ART

Heretofore, in a vehicle rear suspension structure for suspending a wheel by a trailing arm integrated with a wheel carrying member to extend in a longitudinal (frontward-rearward) direction of a vehicle (hereinafter referred to as “vehicle longitudinal direction”), and upper and lower lateral links extending in a widthwise (rightward-leftward) direction of the vehicle (hereinafter referred to as “vehicle widthwise direction”) in approximately parallel relation to each other and at an acute angle with respect to the trailing arm in top plan view, a technique has been implemented in which a stabilizer is provided to couple a pair of right and left wheel suspension members together, wherein a fixation angle at which the stabilizer is fixedly mounted to each of the wheel suspension members, is set to allow the stabilizer to become approximately parallel to an instantaneous rotation axis of the wheel, which connects an apparent rotation center defined by the upper and lower lateral links in a stopped or static state of the wheel, and a pivot point of the trailing arm, so as to prevent the occurrence of torsion between the stabilizer and the wheel suspension member to ensure reliability of a mounting section therebetween, as disclosed in the following PTL 1.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In the vehicle rear suspension structure disclosed in the PTL 1, the stabilizer is disposed below a subframe installed to couple the right and left wheel suspension members together, and a stabilizer support section is installed rearward of the subframe to support a central portion of the stabilizer, and fixed to a vehicle body (so as to allow the stabilizer to be mounted to a vehicle body) through a clamping bracket installed rearward of the subframe to extend in an upward-rearward direction. However, there is a problem, for example, that it is difficult in terms of layout to adequately install the stabilizer clamping bracket without causing interference with the subframe, and a supported state of the stabilizer based on the clamping bracket is likely to become unstable.

In view of the above problem, the present invention is directed to providing a vehicle suspension apparatus capable of effectively improving rigidity of a subframe installed to couple right and left wheel suspension members together, with a simple configuration, and adequately installing a stabilizer so as to effectively bring out its function.

Solution to Problem

In order to solve the above problem, the present invention provides a vehicle suspension apparatus which comprises: a wheel carrying member (1) adapted to rotatably carry a wheel; a pair of right and left wheel suspension members (2;7) each including a lateral link (5,6) having one end mounted to the wheel carrying member (1); a subframe (3) installed to couple the right and left wheel suspension members together; and a stabilizer (10). The subframe (3) includes: a cross member (31) installed to extend in a vehicle widthwise direction and provided with a lateral-link support portion (14,18) supporting the other end of the lateral link (5,6); a pair of right and left side members (33) each extending from a respective one of opposite vehicle-widthwise outer ends of the cross member, in a vehicle longitudinal direction; and a pair of right and left reinforcing members (35) each reinforcing a coupling section between the lateral-link support portion (14,18) of the cross member (31) or a vicinity thereof, and a respective one of the side members (33). The stabilizer (10) is installed at a position vertically higher than that of the cross member (31). The stabilizer (10) has a stabilizer body (49) provided to extend in the vehicle widthwise direction, and a pair of right and left extension portions (50) each extending from a respective one of opposite right and left ends of the stabilizer body (49), in the vehicle longitudinal direction. Each of the reinforcing members (35) is provided with a stabilizer support section (47) rollably supporting a corresponding one of the right and left ends of the stabilizer body (49), and each of the extension portions (50) has a distal end coupled to a corresponding one of the right and left wheel suspension members (2;7) through a coupling link (25).

In the present invention, the vehicle suspension apparatus is provided with the reinforcing members each reinforcing the coupling section between the lateral-link support portion of the cross member or the vicinity thereof, and a respective one of the side members, so that it becomes possible to effectively reinforce the coupling section between the lateral-link support portion provided in the cross member or the vicinity thereof, and the side member, so as to effectively improve rigidity of the subframe. In addition, the stabilizer (10) is installed at a position higher than that of the cross member, and has the stabilizer body (49) extending in the vehicle widthwise direction and the right and left extension portions (50) each extending from a respective one of the right and left ends of the stabilizer body (49), in the vehicle longitudinal direction. Further, each of the reinforcing members (35) is provided with the stabilizer support section rollably supporting a corresponding one of the right and left ends of the stabilizer body (49), and each of the extension portions (50) has a distal end coupled to a corresponding one of the right and left wheel suspension members (2;7) through the coupling link (25). This makes it possible to stably support the stabilizer body to the cross member, and reduce a vehicle-widthwise offset amount (distance) between the stabilizer support section and the extension portion at each of the right and left ends of the stabilizer body. Furthermore, a load input into one of the wheel suspension members during vehicle turning can be efficiently transmitted to the stabilizer body through the coupling link and the extension portion to allow the stabilizer body to be reliably twisted so as to effectively produce a reaction force for suppressing a roll displacement of a vehicle body. In other words, the present invention has an advantage of being able to install the stabilizer at an adequate position so as to effectively bring out its function, with a simple configuration.

DESCRIPTION OF EMBODIMENTS

FIGS. 1 to 3illustrate a vehicle suspension apparatus according to one embodiment of the present invention. The suspension apparatus comprises a wheel carrying member1made of a casting material or the like and adapted to rotatably carry a wheel consisting of a rear wheel of a vehicle, a pair of right and left wheel suspension members2each supporting the wheel carrying member1, and a subframe3disposed in a rear of a vehicle body to couple the right and left wheel suspension members2together.

Each of the wheel suspension members2includes: a trailing arm4having one end mounted to the wheel carrying member1; a pair of upper and lower lateral links5,6each having one end swingably mounted to the wheel carrying member1and the other end swingably supported by the vehicle body, while being installed to extend in a vehicle widthwise direction; a lower link7disposed rearward of the upper and lower lateral links; a shock absorber8having a lower end supported by the wheel carrying member1; a suspension spring9having a lower end supported by the lower link7; and a stabilizer10installed to extend in the vehicle widthwise direction while passing above the subframe3.

The trailing arm4is formed as a component prepared by subjecting a steel plate to press forming and installed to extend in a vehicle longitudinal direction. One end (rear end) of the trailing arm4is bolted to the wheel carrying member1, and a front end (the other end) of the trailing arm4is supported by a rear side frame11constituting a frame of the vehicle body, through a rubber bush in an elastically displaceable manner.

As illustrated inFIGS. 3 to 5, etc., the lateral links5,6are disposed above and below a rotary shaft S of the wheel, respectively, across the rotary shaft S. One end (vehicle-widthwise outer end) of the upper, first, lateral link5is mounted to a lateral-link mounting portion12provided in an upper portion of the wheel carrying member1at a position frontward of the rotary shaft S, through a rubber bush13in an elastically displaceable manner. The other end (vehicle-widthwise inner end) of the first lateral link5is supported by an upper lateral-link support portion14provided on an upper side of the subframe3, through a rubber bush15in an elastically displaceable manner.

One end (vehicle-widthwise outer end) of the second lateral link6disposed below the rotary shaft S of the wheel is mounted to a lateral-link mounting portion16provided in a lower portion of the wheel carrying member1at a position frontward of the rotary shaft S, through a rubber bush17in an elastically displaceable manner. The other end (vehicle-widthwise inner end) of the second lateral link6is swingably supported by a lower lateral-link support portion18provided on a lower side of the subframe3, through a rubber bush19.

In side view, the lateral-link mounting portions12,16are disposed above and below the rotary shaft S in spaced-apart relation to each other by a given distance, and disposed frontward of the rotary shaft S of the wheel and at approximately the same positions in the vehicle longitudinal direction. Similarly, in side view, the upper and lower lateral-link support portions14,18provided in the subframe3are disposed above and below the rotary shaft S in spaced-apart relation to each other by a given distance, and disposed frontward of the rotary shaft S of the wheel and at approximately the same positions in the vehicle longitudinal direction.

One end (vehicle-widthwise outer end) of the lower link7is mounted to a lower-link mounting portion20provided in a lower portion of the wheel carrying member1at a position rearward of the rotary shaft S of the wheel, through a rubber bush21in an elastically displaceable manner. The other end (vehicle-widthwise inner end) of the lower link7is supported by a lower-link support portion22provided in a rear portion of the subframe3, through a rubber bush23in an elastically displaceable manner.

Each of the rubber bushes21,23provided in the mounting portion20and the support portion22for the lower link7has a hardness set to a highest value, i.e., a first hardness, and each of the rubber bushes17,19provided in the mounting portion16and the support portion18for the second lateral link6has a hardness set to a lowest value, i.e., a second hardness. Further, each of the rubber bushes13,15provided in the mounting portion12and the support portion14for the first lateral link5has a hardness set to an intermediate value between the first hardness and the second hardness.

The lower link7has a concave portion24formed to support the lower end of the suspension spring9. The suspension spring9is disposed to extend between the concave portion24and the rear side frame11located above the concave portion24. The lower link7also has a lock portion26which locks a lower end of a coupling link25provided at each of opposite lateral (vehicle-widthwise outer) ends of the stabilizer10to extend in an upward-downward direction (seeFIG. 5). The lock portion26for the stabilizer10is disposed at a vehicle-widthwise inner position with respect to the upper and lower lateral-link support portions14,18provided in the subframe3, to rollably support a ball joint provided at the lower end of the coupling link25.

The shock absorber8is installed at a position rearward of the rotary shaft S of the wheel to extend in an upward-downward direction in a posture inclined frontwardly by a given angle. The lower end of the shock absorber8is rigidly joined to the wheel carrying member1by bolting, and an upper end of the shock absorber8is supported by a strut tower (not illustrated) constituting the frame of the vehicle body, through a rubber insulator or the like.

As illustrated inFIGS. 1 and 2, etc, the subframe3includes: a front cross member31installed to extend in the vehicle widthwise direction at a position frontward of the rotary shaft S of the wheel; a rear cross member32installed to extend in the vehicle widthwise direction at a position rearward of the rotary shaft S; a pair of right and left side members33each extending from a respective one of opposite vehicle-widthwise outer ends of each of the front and rear cross members, in the vehicle longitudinal direction; a pair of right and left connection members34each connecting the front cross member31and the rear cross member32at a vehicle-widthwise inner position with respect to a corresponding one of the side members33; and a pair of right and left reinforcing members35each reinforcing a coupling section between the front cross member31and a respective one of the side members33.

As illustrated inFIG. 3, in front view, the front cross member31includes a first front cross member36extending obliquely to couple the upper lateral-link support portion14provided on a left upper side of the front cross member31and the lower lateral-link support portion18provided on a right lower side of the front cross member31, and a second front cross member37extending obliquely to couple the upper lateral-link support portion14provided on a right upper side of the front cross member31and the lower lateral-link support portion18provided a left lower side of the front cross member31. Thus, the first and second front cross members36,37intersect to form an X shape in front view. Respective lateral ends of the first and second front cross members36,37are installed in spaced-apart relation to each other by a given distance in an upward-downward direction, in side view, so that a frame member extending in the upward-downward direction is formed at each of opposite lateral ends of the front cross member31, as illustrated inFIG. 6.

The rear cross member32is installed to extend in the vehicle widthwise direction in such a manner as to couple the right and left side members33. Further, the pair of right and left lower-link support portions22are provided in the rear cross member32, and the vehicle-widthwise inner end of the lower link7is swingably supported by each of the right and left lower-link support portions22through the rubber bush23(seeFIG. 3).

Each of the side members33of the subframe3is installed to extend in the vehicle longitudinal direction while passing between the upper and lower lateral-link support portions14,18provided at a corresponding one of the lateral ends of the front cross member31. The side member33is connected to respective lateral ends of the front cross member31and the rear cross member32, so that the front cross member31and the rear cross member32are coupled together by the side member33.

The side member33has a front portion42provided to protrude frontwardly and outwardly from the lateral end of the front cross member31, and a rear portion43provided to protrude rearwardly and outwardly from the lateral end of the rear cross member32. Thus, in front view, the side member33is formed in a semi-circular shape having a longitudinally central portion curved concavedly and inwardly in the vehicle widthwise direction. Further, a front mount portion44and a rear mount portion45are provided, respectively, at distal ends of the front portion42and the rear portion43, and the side member33is connected to the lateral ends of the front and rear cross members31,32at a position where the side member33is concavedly curved inwardly with respect to the front and rear mount portions44,45in the vehicle widthwise direction.

As illustrated inFIGS. 6 and 7, the upper lateral-link support portion14or a vicinity thereof, and the side member33, are coupled together through the reinforcing member35provided on a top portion of the front cross member31, so that a coupling section between the front cross member31and the side member33is reinforced. More specifically, a triangular pawl-shaped protrusion46provided in a front portion of the reinforcing member35is joined to a top surface and a rear surface of the front cross member31, and a rear portion of the reinforcing member35is joined to a top surface and a vehicle-widthwise inner side surface of the side member33. In this manner, a coupling section between a vicinity of the upper lateral-link support portion14provided on an upper side of the lateral end of the front cross member31, and a top surface portion of the side member33, is reinforced. Specifically, each of the reinforcing members35has a front portion formed as the protrusion46and joined to the top and rear surfaces of the front cross member31, a rear portion joined to the top and vehicle-widthwise inner side surfaces of the side member33, and a top surface portion disposed in a posture inclined frontwardly and upwardly. Thus, based on the reinforcing member35disposed in the inclined posture, an effect of preventing tilting of the front cross member31in the vehicle longitudinal direction can be improved to enhance an effect of reinforcing the coupling section between the front cross member31and the side member33.

Further, a mounting bolt48is provided to protrude from a top surface of the reinforcing member35so as to allow a support bracket47of the stabilizer10to be mounted to the top surface. In top plan view, the stabilizer10has a stabilizer body49installed to extend in the vehicle widthwise direction, and a pair of right and left extension portions50each provided to extend from a respective one of opposite right and left ends of the stabilizer body49, in the vehicle longitudinal direction. Each of the right and left ends of the stabilizer body49is rollably supported by a support member51which is fixed to the top surface of the reinforcing member35through the support bracket47. As above, a stabilizer support section comprising the support bracket47is provided on the top surface portion of the reinforcing member35disposed in the inclined posture. Thus, a dimension of an upwardly protruding portion of the stabilizer support section is reduced, so that the stabilizer10can be compactly disposed rearward of the front cross member31.

The extension portion50of the stabilizer10and the lock portion26of the lower link7are coupled together through the coupling link25. Thus, each of opposite vehicle-widthwise ends of the stabilizer10can be locked to the wheel suspension member2at a vehicle-widthwise inner position with respect to the upper and lower lateral-link support portions14,18of the front cross member31. Then, an external force, such as a push-up force, input into one of the right and left lower links7during vehicle running is transmitted to the other lower link7via the stabilizer10and the right and left coupling links25, to suppress inclination of the vehicle body during vehicle turning.

As above, the vehicle suspension apparatus according to the above embodiment comprises a wheel carrying member1adapted to rotatably carry a wheel, a pair of right and left wheel suspension members2each including a lateral link5,6having one end mounted to the wheel carrying member1, a subframe3installed to couple the right and left wheel suspension members2together, and a stabilizer10. The subframe3includes: a front cross member31installed to extend in a vehicle widthwise direction and provided with a lateral-link support portion14,18supporting the other end of the lateral link5,6; a pair of right and left side members33each extending from a respective one of opposite vehicle-widthwise outer ends of the front cross member31, in a vehicle longitudinal direction; and a pair of right and left reinforcing members35each reinforcing a coupling section between the lateral-link support portion14,18of the front cross member31or a vicinity thereof, and a respective one of the side members33. The stabilizer10is installed at a position higher than that of the front cross member31to generally extend in the vehicle widthwise direction, and each of the reinforcing members35is provided with a stabilizer support section (the aforementioned support bracket47, etc.) rollably supporting a corresponding one of opposite right and left ends of a stabilizer body49of the stabilizer10installed to extend in the vehicle widthwise direction. Thus, it becomes possible to effectively reinforce the coupling section between the vicinity of the lateral-link support portion14,18provided in the front cross member31, and a respective one of the side members33, so as to sufficiently enhance rigidity of the subframe3. In the above embodiment, the stabilizer10is installed to extend in the vehicle widthwise direction at a position above the front cross member31, and each of the reinforcing members35is provided with the stabilizer support section rollably supporting the corresponding end of the stabilizer body49installed to extend in the vehicle widthwise direction. Further, a distal end of each of a pair of right and left extension portions50provided to extend from respective ones of the right and left ends of the stabilizer body49is coupled to a corresponding one of the wheel suspension members2(the aforementioned right and left lower links7). Thus, it becomes possible to stably support the stabilizer body49to the front cross member31, and reduce a vehicle-widthwise offset amount (distance) between the stabilizer support section and the extension portion50at each of the right and left ends of the stabilizer body49. In addition, it becomes possible to efficiently transmit a load input into one of the wheel suspension members2during vehicle turning, to the stabilizer body49through the coupling link25and the extension portion50to allow the stabilizer body49to be reliably twisted so as to effectively produce a reaction force for suppressing a roll displacement of a vehicle body. In other words, the above embodiment has an advantage of being able to install the stabilizer at an adequate position so as to effectively bring out its function, with a simple configuration.

More specifically, in the above embodiment, the support bracket47is mounted to a top surface of each of the reinforcing member35installed to reinforce the coupling section between the vicinity of the lateral-link support portion14,18and a respective one of the side members33, by means of a mounting bolt48provided to protrude from the top surface, and each of the right and left ends of the stabilizer body51is rollably supported based on a support member51held by the support bracket47, so that it becomes possible to allow the each of the reinforcing members35to have both a function as a reinforcing bracket for reinforcing the coupling section between the front cross member31and the side member31, and a function as the stabilizer support section. This provides an advantage of being able to effectively reinforce the coupling section between the vicinity of the lateral-link support portion14,18provided in the front cross member31, and the side member33, so as to effectively improve rigidity of the subframe3, with a simple configuration, and adequately install the stabilizer10so as to effectively bring out its function.

In the above embodiment, each of opposite widthwise ends of the stabilizer10is locked to a respective one of the wheel suspension members2, specifically, the lower links7, at a vehicle-widthwise inner position with respect to the lateral-link support portion14,18of the front cross member31, so that it becomes possible to prevent the occurrence of a situation where a portion of the stabilizer10rotatably supported by the support bracket47and the support member51, and a lock portion26provided in the wheel suspension member2to lock the stabilizer10, are largely offset in the vehicle widthwise direction, which provides an advantage of being able to sufficiently bring out the function of the stabilizer10so as to effectively suppress the roll displacement of the vehicle body.

As disclosed in the above embodiment, each of the reinforcing members35has a front portion formed as a protrusion46and joined to a top surface and a rear surface of the front cross member31, a rear portion joined to a top surface and a vehicle-widthwise inner side surface of a corresponding one of the side members33, and a top surface portion disposed in a posture inclined frontwardly and upwardly. Thus, based on the reinforcing member35disposed in the inclined posture, an effect of preventing tilting of the front cross member31in the vehicle longitudinal direction can be improved to enhance an effect of reinforcing the coupling section between the front cross member31and the side member33. Further, a stabilizer support section comprising the support bracket47is provided on the top surface portion of the reinforcing member35disposed in the inclined posture. Thus, a dimension of an upwardly protruding portion of the stabilizer support section is reduced, so that the stabilizer10can be compactly disposed rearward of the front cross member31.

In the above embodiment, each of the wheel suspension members includes, as the lateral link, a pair of upper and lower lateral links5,6each having one, first, end swingably mounted to the wheel carrying member1and the other, second, end swingably supported by the vehicle body, while being installed to extend in the vehicle widthwise direction, and further comprises a lower link7having one end mounted to a lower portion of the wheel carrying member at a position rearward of the rotary shaft S of the wheel and the other end swingably supported by the vehicle body. The first ends of the upper and lower lateral links5,6are mounted to an upper portion and a lower portion of the wheel carrying member1at positions frontward of the rotary shaft S of the wheel, and respective mounting portions12,16for mounting the upper and lower lateral links5,6are disposed at approximately the same positions in the vehicle longitudinal direction in side view. This provides an advantage of being able to obtain excellent suspension performance, and effectively enhance steering stability during vehicle turning, with a simple configuration.

Specifically, in the above embodiment, a pair of upper and lower lateral-link support portions14,18are provided, respectively, at opposite right and left ends of the front cross member31constituting the subframe3installed to couple the right and left wheel suspension members2, and one end of the lower link7disposed rearward of the upper and lower lateral-link support portions14,18is swingably supported by the vehicle body at a position rearward of the rotary shaft S of the wheel, so that vehicle steering stability can be effectively enhanced by biasing a turning outer wheel (rear wheel located on an outer side during vehicle turning), toward a direction causing toe-in (toe-in direction). The term “toe-in” means that a front end (called “toe”) of a tire is moved into an inward side of a vehicle body on the basis of a vehicle body oriented in a traveling direction. Conversely, a state when the toe is moved outwardly is referred to as “toe-out”.

For example, as illustrated inFIG. 8, in a situation where a vehicle is turning counter-clockwise, an centrifugal force B causing a vehicle body A to be moved rightwardly, and a cornering force D biasing a tire ground point of each wheel inwardly against the centrifugal force B, act on the vehicle. Thus, as illustrated inFIGS. 9 and 10, according to the cornering force D acting on an turning outer wheel C which is a rear wheel located on an outer side with respect to a turning direction, a compression stress G1and a compression stress G2are produced, respectively, in a second lateral link6and a lower link7each located below a rotary shaft S of the turning outer wheel C serving as a support point, and a tensile stress H is produced in a first lateral link5located above the rotary shaft S.

In the top plan view illustrated inFIG. 10, in the second lateral link6disposed below the first lateral link5and rearward of the rotary shaft S, the compression stress G1is produced correspondingly to both the cornering force D and the tensile stress H produced in the first lateral link5. Differently, in the lower link7disposed rearward of the rotary shaft S, the compression stress G2is produced correspondingly to only the cornering force D, i.e., a stress having a value less than the compression stress G1acting on the second lateral link6is produced.

As above, based on balance in rotation moment about an installation location of the rotary shaft S, the compression stress greater than that in the lower link7located rearward of the rotary shaft S is produced in the second lateral link6located frontward of the rotary shaft S. Thus, rubber bushes17,19provided in the second lateral link6is compressively deformed more largely than rubber bushes21,23provided in the lower link7, and thereby the turning outer wheel C is deformed in a toe-in direction.

Based on stress calculation, it was tested how a toe-in angle of the turning outer wheel C is changed along with an increase in inward cornering force D acting on the turning outer wheel C. As a result, it was ascertained that the toe-in angle of the turning outer wheel C is changed to a plus direction along with an increase in the inward cornering force D, as shown inFIG. 11.

On the other hand, using a comparative example where a first lateral link5ais disposed at a position between the second lateral link6and the lower link7and closer to the lower link7, i.e., disposed slightly rearward of the rotary shaft S, as illustrated inFIG. 12, it was tested how the toe-in angle of the turning outer wheel C is changed along with an increase in inward cornering force D acting on the turning outer wheel C, based on stress calculation. As a result, it was ascertained that the toe-in angle of the turning outer wheel C is changed to a minus direction (toe-out direction) along with an increase in the inward cornering force D, as shown inFIG. 13, and thereby steering stability is deteriorated.

Further, in the above embodiment, the first ends of the first and second lateral links5,6are mounted to respective one of the upper and lower portions of the wheel carrying member1at a position frontward of the rotary shaft S of the wheel, and the respective mounting portions12,16for mounting the upper and lower lateral links5,6are disposed at approximately the same positions in the vehicle longitudinal direction in side view, as described above. This also provides an advantage of being able to perform an operation such as design change or tuning for optimizing a change in geometry of the suspension apparatus during wheel bump, in an easy and adequate manner. Specifically, in order to effectively improve vehicle ride quality, it is desirable to set a correspondence relationship between a wheel bump amount and a toe-in angle, a correspondence relationship between the wheel bump amount and a camber angle, and a correspondence relationship between the wheel bump amount and a roll-center height, in respective manners as illustrated inFIG. 14,FIG. 15andFIG. 16. The term “camber angle” means an angle at which an upper portion of a tire is inclined outwardly or inwardly (inverted V shape), when viewed from a front of a vehicle. An outwardly-inclined angle is called, “positive camber”, and an inwardly-inclined angle is called, “negative camber”. The term “roll center” means a center of rolling (: rolling about a segment line extending in a vehicle traveling direction) of a vehicle body, when viewed from a front (or rear) of a vehicle, and the term “roll-center height” means a height of the roll center.

In a conventional apparatus where the first lateral link5ais disposed between the second lateral link6and the lower link7, when one of respective instruction positions, lengths or the like of the first lateral link5a, the second lateral link6and the lower link7is changed to set the correspondence relationship between the wheel bump amount and the toe-in angle to an adequate value as illustrated inFIG. 13, the correspondence relationship between the wheel bump amount and the camber angle and the correspondence relationship between the wheel bump amount and the roll-center height will be inevitably changed. Thus, if these relationships become inadequate, it is necessary to restart the design from the beginning. Moreover, it is extremely difficult to set all of the relationships to adequate values.

In contract, in the above embodiment where the first ends of the first and second lateral links5,6are mounted to respective one of the upper and lower portions of the wheel carrying member1at a position frontward of the rotary shaft of the wheel, and the respective mounting portions12,16for mounting the upper and lower lateral links5,6are disposed at approximately the same positions in the vehicle longitudinal direction in side view, wherein the lower link7is disposed rearward of the rotary shaft, even if one of respective instruction positions, lengths or the like of the first to third lateral links5to7is changed to set one of a plurality of characteristics to an adequate value, the remaining characteristics will not be largely changed, which provides an advantage of being able to facilitate the above operation such as design change.

As disclosed in the above embodiment, a frame member comprised of the front cross member31of the subframe3comprises a first front cross member36and a second front cross member37arranged to intersect to form an X shape in front view, and the pair of upper and lower lateral link support portions14,18are disposed at each of opposite right and left end regions of the first and second front cross members36,37. This provides an advantage of being able to effectively enhance the rigidity in the vehicle widthwise direction

In the above configuration, for example, during clockwise vehicle turning, a load is applied to the left lower lateral-link support portion18in a direction causing the front cross member31to be compressed, and simultaneously a load is applied to the right upper lateral-link support portion14located in diagonal relation to the left lower lateral-link support portion18, in a direction causing the front cross member31to be compressed, so that the two loads will be canceled out. Further, a load is applied to the left upper lateral-link support portion14in a direction causing the front cross member31to be tensioned, and simultaneously a load is applied to the right lower lateral-link support portion18located in diagonal relation to the left upper lateral-link support portion14, in a direction causing the front cross member31to be tensioned, so that the two loads will be canceled out. This provides an advantage of being able to effectively support an input load from the right and left wheel suspension members2, while simplifying a structure of the front cross member31.

As disclosed in the above embodiment, the pair of right and left side members33each extending from a respective one of opposite right and left edges of the front cross member31, in a vehicle longitudinal direction, and a rear cross member32extending in the vehicle widthwise direction to couple respective rear portions of the side members33, are provided, and the lower link7is swingably supported by the rear cross member32. This provides an advantage of stably support a load input from the lower link7into the subframe3, with a simple configuration.

In the above embodiment, each of the rubber bushes21,23provided in the mounting portion20and the support portion22for the lower link7has a hardness set to a highest value, i.e., a first hardness, and each of the rubber bushes17,19provided in the mounting portion16and the support portion18for the second lateral link6has a hardness set to a lowest value, i.e., a second hardness. Further, each of the rubber bushes13,15provided in the mounting portion12and the support portion14for the first lateral link5has a hardness set to an intermediate value between the first hardness and the second hardness. Thus, the second lateral link6disposed below and frontward of the rotary shaft of the wheel can be most largely elastically deformed to allow a turning outer wheel to be more effectively displaced to a toe-in position during vehicle turning.

However, it is not essential to set hardness of each of the rubber bushes13,15,17,19,21,23provided in the mounting portion12and the support portion14for the first lateral link5, the mounting portion16and the support portion18for the second lateral link6, and the mounting portion20and the support portion22for the lower link7, in the above manner. For example, only the rubber bushes13,17,21provided in the mounting portion12for the first lateral link5, and the mounting portion16for the second lateral link6and the mounting portion20for the lower link7may be designed to become different from each other in hardness. Conversely, only the rubber bushes15,19,23provided in the support portion14for the first lateral link5, the support portion18for the second lateral link6, and the support portion22for the lower link7may be designed to become different from each other in hardness. Even in these structures, it is possible to allow a turning outer wheel to be more effectively displaced to a toe-in position during vehicle turning.

As disclosed in the above embodiment, each of the side members33of the subframe3is provided with a pair of front and rear mount portions45,46each adapted to be mounted to a rear side frame11of a vehicle body, wherein the side member33is connected to the front cross member31and the rear cross member, at a position where the side member33is concavedly curved inwardly with respect to the front and rear mount portions44,45in the vehicle widthwise direction. For example, this provides an advantage of being able to adequately couple the rear side frame11and the side member33of the subframe3so as to effectively enhance the rigidity of the vehicle body, while ensuring a space for installing a coupling link25for the stabilizer10between the rear side frame11and the side member33.

In the above embodiment, a shock absorber8is installed to extend downwardly, at a position rearward of the rotary shaft of the wheel, and a lower end of the shock absorber8is supported by the wheel carrying member1, so that it becomes possible to sufficiently ensure an installation space of the shock absorber8, by effectively utilizing a space formed on a rear side of the wheel carrying member1based on the arrangement where the first lateral link5is disposed frontward of the wheel carrying member1. In addition, it is not necessary to change an installation position of the shock absorber8between a rear-wheel-drive or four-wheel-drive vehicle having a need for transmitting a driving force of an engine to rear wheels, and a front-wheel-drive vehicle free of the need for transmitting a driving force of an engine to rear wheels, so that it becomes possible to allow the suspension apparatus to have versatility as a rear-wheel suspension apparatus.

Particularly, as disclosed in the above embodiment, the shock absorber8is installed in a frontwardly-inclined posture by utilizing the space formed on the rear side of the wheel carrying member1. For example, this provides an advantage of effectively enhance vehicle ride quality with a simple configuration, by using the shock absorber8as a damping member against up-and-down vibration input from the rear wheel suspension member2, while effectively compactifying a installation space of the shock absorber8.

An outline of the present invention based on the above embodiment:

The present invention provided a vehicle suspension apparatus which comprises: a wheel carrying member (1) adapted to rotatably carry a wheel; a pair of right and left wheel suspension members (2;7) each including a lateral link (5,6) having one end mounted to the wheel carrying member (1); a subframe (3) installed to couple the right and left wheel suspension members together; and a stabilizer (10), characterized in that the subframe (3) includes: a cross member (31) installed to extend in a vehicle widthwise direction and provided with a lateral-link support portion (14,18) supporting the other end of the lateral link (5,6); a pair of right and left side members (33) each extending from a respective one of opposite vehicle-widthwise outer ends of the cross member, in a vehicle longitudinal direction; and a pair of right and left reinforcing members (35) each reinforcing a coupling section between the lateral-link support portion (14,18) of the cross member (31) or a vicinity thereof, and a respective one of the side members (33), and the stabilizer (10) is installed at a position higher than that of the cross member (31), wherein the stabilizer (10) has a stabilizer body (49) provided to extend in the vehicle widthwise direction, and a pair of right and left extension portions (50) each extending from a respective one of opposite right and left ends of the stabilizer body (49), in the vehicle longitudinal direction, and wherein: each of the reinforcing members (35) is provided with a stabilizer support section (47) rollably supporting a corresponding one of the right and left ends of the stabilizer body (49); and each of the extension portions (50) has a distal end coupled to a corresponding one of the right and left wheel suspension members (2;7) through a coupling link (25).

In the present invention, the vehicle suspension apparatus is provided with the reinforcing members each reinforcing the coupling section between the lateral-link support portion of the cross member or the vicinity thereof, and a respective one of the side members, so that it becomes possible to effectively reinforce the coupling section between the lateral-link support portion provided in the cross member or the vicinity thereof, and the side member, so as to effectively improve rigidity of the subframe. In addition, the stabilizer (10) is installed at a position higher than that of the cross member, and has the stabilizer body (49) extending in the vehicle widthwise direction and the right and left extension portions (50) each extending from a respective one of the right and left ends of the stabilizer body (49), in the vehicle longitudinal direction. Further, each of the reinforcing members (35) is provided with the stabilizer support section rollably supporting a corresponding one of the right and left ends of the stabilizer body (49), and each of the extension portions (50) has a distal end coupled to a corresponding one of the right and left wheel suspension members (2;7) through the coupling link (25), so that it becomes possible to stably support the stabilizer body to the cross member, and reduce a vehicle-widthwise offset amount (distance) between the stabilizer support section and the extension portion at each of the right and left ends of the stabilizer body. This makes it possible to efficiently transmit a load input into one of the wheel suspension members during vehicle turning, to the stabilizer body through the coupling link and the extension portion, so as to allow the stabilizer body to be reliably twisted so as to effectively produce a reaction force for suppressing a roll displacement of a vehicle body. In other words, the present invention has an advantage of being able to install the stabilizer at an adequate position so as to effectively bring out its function, with a simple configuration.

Preferably, as one embodiment of the present invention, the distal end of each of the extension portions (50) of the stabilizer (10) is locked to a corresponding one of the wheel suspension members (7) through the coupling link (25), at a vehicle-widthwise inner position with respect to the lateral-link support portion (14,18). As above, the distal end of each of the extension portions of the stabilizer is locked to a corresponding one of the wheel suspension members through the coupling link (25), at a vehicle-widthwise inner position with respect to the lateral-link support portion of the cross member. This provides an advantage of being able to prevent the occurrence of a situation where the stabilizer support section and a lock portion for locking the stabilizer to the wheel suspension member, are largely offset in the vehicle widthwise direction, and sufficiently bring out the function of the stabilizer so as to effectively suppress the roll displacement of the vehicle body.

Preferably, each of the reinforcing members (35) has a front portion coupled to the cross member (31), a rear portion coupled to a corresponding one of the side members (33), and a top surface portion disposed in a posture inclined rearwardly and downwardly, wherein the stabilizer support section (47) is provided on the top surface portion of the reinforcing member (35). According to this feature, each of the reinforcing members has the front portion coupled to the cross member, the rear portion coupled to the side member, and a top surface portion disposed in a posture inclined rearwardly and downwardly, wherein the stabilizer support section is provided on the top surface portion of the reinforcing member. Thus, based on the reinforcing member disposed in the inclined posture, an effect of preventing tilting of the front cross member in the vehicle longitudinal direction can be improved to enhance an effect of reinforcing the coupling section between the front cross member and the side member. Further, based on providing the stabilizer support section on the inclined top surface portion of the reinforcing member, a dimension of an upwardly protruding portion of the stabilizer support section is reduced, so that the stabilizer can be compactly disposed.

Preferably, each of the wheel suspension members includes an upper lateral link (5) and a lower lateral link (6), wherein ends of the upper and lower lateral links (5,6) on the side of the wheel carrying member (1) are supported, respectively, by an upper portion and a lower portion of the wheel carrying member (11) at positions frontward of a rotary shaft (S) of the wheel, and the upper and lower lateral-link support portions (12,16) provided in the wheel carrying member (1) are disposed at approximately same positions in the vehicle longitudinal direction in side view. This provides an advantage of being able to obtain excellent suspension performance, and effectively enhance steering stability during vehicle turning, with a simple configuration.

Preferably, each of the side members (33) of the subframe (3) is provided with a pair of front and rear mount portions (44,45) each adapted to be mounted to a rear side frame (11) of a vehicle body, wherein the side member (33) is connected to the cross member (31) at a position where the side member (33) is concavedly curved inwardly with respect to the front and rear mount portions (44,45) in the vehicle widthwise direction. According to this feature, each of the side members of the subframe is provided with the pair of front and rear mount portions each adapted to be mounted to a rear side frame of a vehicle body, wherein the side member is connected to the cross member at a position where the side member is concavedly curved inwardly with respect to the front and rear mount portions in the vehicle widthwise direction. For example, this provides an advantage of being able to adequately couple the rear side frame and the side frame so as to effectively reinforce the vehicle body, while ensuring a space for installing the coupling link for the stabilizer, etc., between the rear side frame and the side frame.

This application is based on Japanese Patent Application Serial No. 2010-150050 filed in Japan Patent Office on Jun. 30, 2010 the contents of which are hereby incorporated by reference.