JP6565410B2 - Rack and pinion steering system - Google Patents

Description

  The present invention relates to an improvement of a rack housing of a rack and pinion type steering apparatus.

  In automobiles, the ball screw type and the rack and pinion type are known as mechanisms for converting the rotation of the steering shaft to which the steering wheel is attached to the movement of the left and right steering wheels. The rack and pinion type is mainly used for reasons such as high. This rack-and-pinion type mechanism bites the pinion teeth formed on the pinion shaft connected via the steering shaft, intermediate shaft, universal joint, etc., and the rack teeth formed on the rack shaft extending in the vehicle width direction. By combining them, the rotational motion of the steering wheel is converted into the linear motion of the rack shaft.

  Tie rods connected to the steering wheel are connected to both ends of the rack shaft, and the movement of the steering wheel is controlled by movement of the rack shaft in the axial direction (vehicle width direction). Conversely, the reaction force acting on the steered wheel from the road surface is transmitted to the steering wheel via the route opposite to the above, that is, the tie rod and the rack shaft.

  The rack shaft is required to have the function of transmitting the axial force described above and the function of receiving the reaction force acting on the steered wheels. To achieve this function, the engagement between the rack teeth and the pinion teeth is ensured. In addition to being maintained, it is necessary to reliably support the force acting on the rack shaft. Under such circumstances, a rack housing for supporting and guiding the rack shaft is generally made of a strong metal material. In recent years, among metal materials, it is becoming a product made from light metal (for example, aluminum) alloy with small specific gravity from iron (for example, refer patent document 1).

JP 2003-285751 A

  However, as described above, since the rack housing needs to have a high strength, when it is made of an aluminum alloy, it is necessary to increase the wall thickness, which inevitably increases the weight.

  In recent years, there has been an increasing demand for reduction of carbon dioxide emission due to global warming, and automobiles are required to have low fuel consumption. Among them, the weight reduction of each part constituting the automobile is being promoted, and the weight reduction is also achieved by optimizing the structure of the steering device. Regarding the rack housing, further weight reduction has been studied from such a viewpoint, but since a metal material is required to maintain the strength, there is a problem that there is a limit to further weight reduction.

  The present invention has been made to solve such a problem, and the rack housing in the rack and pinion type steering device has strength and rigidity equal to or higher than those of the conventional one, and is greatly reduced in weight. An object of the present invention is to provide a rack and pinion type steering device that contributes to a reduction in carbon dioxide emission.

In order to achieve the above object, a rack and pinion type steering apparatus according to the present invention is configured as follows.
Rack and pinion type steering equipped with a pinion shaft formed with pinion teeth, a rack shaft formed with rack teeth meshing with the pinion teeth, and a rack housing for guiding the rack shaft so as to be movable in the axial direction an apparatus,
The rack housing has a first attachment portion and a second attachment portion that are made of metal and attached to a vehicle body, and a pipe-like cylinder portion that connects the first attachment portion and the second attachment portion to each other,
The cylindrical portion is a laminate formed by laminating at least two layers of fiber reinforced plastic sheets , and the fiber angles of the reinforcing fibers included in one of the two adjacent layers and the other layer are different from each other. And
The outer surface of the cylindrical connecting portion formed on the first mounting portion and the second mounting portion and connected to the cylindrical portion protrudes radially outward, and the thickness of the two-layer sheet of the cylindrical portion A plurality of engaging projections having the above length are formed ,
The axial ends of the cylindrical part engage with the connecting part in a state where the engaging convex part penetrates at least the innermost two layers of sheets ,
A rack and pinion type steering device.

  According to the rack and pinion type steering device according to the present invention, the cylindrical portion of the rack housing is formed from a fiber reinforced plastic made of a laminate of at least two layers in which the fiber angles of the reinforcing fibers included are different from each other. Since the connecting portion is connected via an engaging convex portion having a length equal to or greater than the thickness of the two layers of the cylindrical portion, the strength and rigidity are equal to or higher than those of a conventional metal, and The weight can be greatly reduced.

1 is a view showing a rack and pinion type steering device according to the present invention. It is a figure which takes out and shows the rack housing of the steering apparatus of FIG. It is sectional drawing of a rack housing. FIG. 8 is an explanatory view showing, in an enlarged manner, the relationship between the connecting portion of the first mounting portion of the rack housing and the cylindrical portion. FIG. 5 is a perspective view showing a connection part of a first attachment part of a rack housing.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. As shown in FIG. 1, the rack and pinion type steering device 100 of the present embodiment is configured as a column assist type rack and pinion type power steering device, and in order to reduce the operating force of the steering wheel 1, A steering assist force of the motor 2 attached to the steering shaft is applied to a steering shaft (not shown). Then, the rotation of the steering shaft is transmitted to the intermediate shaft 4 via the universal joint 3 and the like, and further transmitted to the pinion shaft 7 via the universal joint 6. By rotation of the pinion shaft 7, the rack shaft 12 of the rack and pinion type steering gear 8 is reciprocated to steer a steered wheel (not shown) via the tie rod 9.

  The steering gear 8 has a rack housing 10, a rack shaft 12, and a pinion shaft 7. The rack shaft 12 has rack teeth on at least a part of the outer periphery, and is supported by the rack housing 10 so as to be reciprocally movable. The pinion shaft 7 has pinion teeth that mesh with the rack teeth of the rack shaft 12, is connected to the steering shaft as described above, and is rotatably supported by the rack housing 10.

  Tie rods 9, 9 are connected to the left and right ends of the rack shaft 12, and the tie rods 9, 9 are connected to the steered wheels via knuckle arms (not shown). Therefore, when the driver rotates the steering wheel 1, the pinion shaft 7 rotates, and the rack shaft 12 slides left and right (vehicle width direction) according to the rotation of the pinion shaft 7, and the steering angle of the steered wheels Can be changed.

  As shown in FIG. 2, the rack housing 10 of the steering gear 8 includes a first attachment portion 14 and a second attachment portion 16, and a pipe-like cylinder portion 18 that connects the attachment portions 14 and 16. .

  The first attachment portion 14 is made of metal, preferably made of aluminum die cast, and is provided so as to protrude from the first annular portion 20 surrounding the rack shaft 12 to the upper side of the vehicle body, and communicates with the first annular portion 20. A cylindrical boss 21 for inserting a pinion, a cylindrical boss 22 for inserting a rack guide adjacent to the cylindrical boss 21, a first boss portion 23 for attaching a vehicle body that can be attached to a vehicle body frame (not shown), Have In the present embodiment, the cylindrical boss 22 protrudes toward the rear of the vehicle body. However, when the rack shaft is positioned on the front side of the vehicle body with respect to the pinion shaft, the cylindrical boss 22 may protrude toward the front side of the vehicle body. .

  The pinion shaft 7 is inserted into the cylindrical boss 21 for pinion insertion, and pinion teeth that mesh with the rack shaft 12 are formed at the lower end of the inserted pinion shaft 7. A rack guide is inserted into the cylindrical boss 22 for inserting a rack guide (not shown). The rack guide urges the back surface (the side opposite to the rack teeth) of the rack shaft 12 in a meshing direction with the pinion teeth via a roller or the like to prevent the rack shaft 12 from being deformed by a reaction force when meshing with the pinion. Thus, the rack shaft 12 slides smoothly.

  A circular mounting hole 23a is formed in the vehicle body vertical direction in the vehicle body mounting first boss portion 23. The first attachment portion 14 is attached to the vehicle body frame by inserting a bolt (not shown) into the attachment hole 23a and tightening the bolt to the vehicle body frame.

  The second mounting portion 16 is also made of metal, preferably made of aluminum die cast, and has a second annular portion 30 surrounding the rack shaft 12 and a second boss portion 33 for mounting the vehicle body that can be attached to the vehicle body frame. The second mounting portion 16 is provided at a predetermined distance from the first mounting portion 14 in the vehicle width direction (left-right direction in FIG. 2).

  A circular mounting hole 33a is formed in the vertical direction of the vehicle body in the second boss portion 33 for mounting the vehicle body. The second attachment portion 16 is attached to the vehicle body frame by inserting a bolt (not shown) into the attachment hole 33a and tightening the bolt to the vehicle body frame.

  The cylindrical portion 18 connects the first annular portion 20 of the first attachment portion 14 and the second annular portion 30 of the second attachment portion 16, and over the whole, the carbon fiber is excellent in strength and rigidity. It is composed of fiber reinforced plastic reinforced. The cylinder portion 18 is not formed alone, but is manufactured as an assembly of the first attachment portion 14 and the second attachment portion 16.

  That is, as shown in FIG. 3, the first mounting portion 14 and the second mounting portion 16 are set around the steel cored bar 40. Next, as shown in FIG. 4, a prepreg containing carbon fibers oriented in one direction is formed on the connecting portions 14a, 16a of the mounting portions 14, 16 and the cored bar 40 with a fiber angle θ of 90 °. It is formed by winding and laminating two layers of different layers. FIG. 4 is an enlarged view of the connecting portion 14a and the prepreg on the first mounting portion 14 side.

  The fiber angle refers to an angle formed by the axial direction of the cored bar 40 and the axial direction of the fiber. Therefore, in FIG. 4, the carbon fiber contained in the first layer 18a, which is one of the two layers, is oriented toward the axial direction of the cored bar 40, so the fiber angle θ = 0. °. Further, since the carbon fiber contained in the second layer 18b, which is the other of the two layers, is oriented perpendicular to the axial direction of the core metal 40, the fiber angle θ = 90 °. It has become. For this reason, the fiber angles θ of the carbon fibers contained in the first layer 18a and the second layer 18b are different from each other by 90 °.

  Although exaggerated in FIG. 4, the thickness of the prepreg is, for example, 0.1 to 0.5 mm. On the other hand, the height of the engaging convex part 14b formed in the connecting part 14a (see also FIG. 5) is 1 to 3 mm, and the thickness of the two layers of these prepregs is 0.2 to 0.2. It is 1 mm or more. For this reason, the engaging convex part 14b penetrates two layers of prepregs having different fiber angles. Therefore, even if a force is applied to pull the cylindrical portion 18 and the first mounting portion 14 away from each other as indicated by a black arrow in the drawing, or the cylindrical portion 18 and the first mounting portion 14 approach each other as indicated by a white arrow. Even if the force to be applied acts, the engaging convex portion 14b is engaged with at least the carbon fiber of the second layer 18b, so both members (the cylindrical portion 18 and the first mounting portion). 14) is maintained.

  In addition, since the connection state of the cylinder part 18 and the 2nd attachment part 16 is also the same, illustration and description are abbreviate | omitted.

  The prepreg contains, for example, 22 to 50 mass%, more preferably 25 to 40 mass% of a thermosetting resin typified by a phenol resin, an epoxy resin, and a thermosetting polyimide resin. When the amount of the thermosetting resin is less than 22% by mass, the resin does not spread between the fibers, the adhesiveness between the prepregs decreases, and voids are easily generated. When the amount exceeds 50% by mass, the number of fibers is increased. Therefore, the strength and rigidity of the prepreg are reduced. The carbon fiber is preferably in a range of 5 to 15 μm in diameter, a tensile strength of 3 to 8.5 GPa, a tensile elastic modulus of 200 to 800 GPa, and an elongation of 1.0 to 2.2%.

  FIG. 5 shows the connecting portion 14a of the first attachment portion 14 taken out, and a plurality of engaging convex portions 14b are formed in the radial direction of the annular connecting portion 14a. Although the engagement protrusion 14b is exaggerated, the thickness of the protrusion is preferably 0.1 to 1 mm in diameter, and the height is 1 to 3 mm as described above.

  As described above, the resin is cured by holding the assembly in which the sheet of prepreg is wound around the cored bar 40 and the first and second mounting portions 14 and 16 and holding them at 130 ° C. for 2 hours. Thereafter, unnecessary portions of the resin are removed by cutting.

  Next, by pulling out the cored bar 40 from the cylindrical part 18 and the assembly of the first and second mounting parts 14 and 16, the rack in which the cylindrical part 18 and the first and second mounting parts 14 and 16 are integrated. The housing 10 is produced.

  Next, the operation of this embodiment will be described.

  As shown in FIG. 1, in the rack and pinion type steering device 1 of the present embodiment, when the pinion shaft 7 is rotated by the operation of the steering wheel 1, this rotational motion is caused by the meshing of the pinion teeth and the rack teeth. The steered wheel is steered by being converted into a linear motion in the axial direction.

  At this time, there is a case in which a force for causing the first and second mounting portions 14 and 16 to approach or separate from each other is exerted by a reaction force acting on the steered wheel from the road surface. However, the connecting portions 14a and 16a of the first and second mounting portions 14 and 16 extend in a direction penetrating the cylindrical portion 18 and have a length equal to or greater than the thickness of the stacked body of the two layers 18a and 18b. Since the engagement protrusions 14b and 16b having a plurality are formed, the engagement protrusions 14b and 16b are engaged with the reinforced carbon fibers of the second layer 18b. It is possible to maintain the positional relationship between the cylindrical portion 18 and the first and second mounting portions 14 and 16 against the above.

  As described above, according to the present embodiment, the cylindrical portion 18 of the rack housing 10 is formed of a fiber reinforced plastic composed of a laminate of at least two layers in which the fiber angles of the carbon fibers included are different from each other. Since the attachment parts 14 and 16 made of metal are connected via the engaging projections 14b and 16b having a length equal to or greater than the thickness of the two layers of the cylindrical part 18, the strength and rigidity are made of conventional metal. It is possible to provide the rack and pinion type steering device 100 which is equal to or more than the case and can be significantly reduced in weight.

  The present invention is not limited to the above-described embodiment, and modifications, improvements, etc. can be made as appropriate. For example, as the prepreg, a unidirectional prepreg in which at least one of a glass fiber and an aramid fiber is oriented in one direction in addition to carbon fibers as a reinforcing fiber, or a woven prepreg in which any of the above fibers is woven can be used.

  Further, the fiber angles of the reinforcing fibers included in each layer of the prepreg to be laminated are not necessarily different from each other by 90 °, and at least one of the adjacent two layers of reinforcing fibers is attached to the first and second attachment portions. It can be set as the arbitrary angle which can be engaged with the engagement convex part formed in the provided connection part.

  Further, the cylindrical portion may be formed by winding not only two layers of prepreg sheets but also stacking them, and winding three or more layers of prepreg sheets.

  In addition to the sheet winding method described above, the cylindrical portion may be formed by a filament winding method in which a filament bundle made of reinforcing fibers is wound while impregnating a liquid thermosetting resin. Furthermore, a braid structure formed in a cylindrical shape may be used, and the cylindrical portion may be formed by impregnating with a thermosetting resin.

7 Pinion shaft 10 Rack housing 12 Rack shaft 14 First mounting portion 16 Second mounting portion 18 Tube portions 14a, 16a Connecting portions 14b, 16b Engaging convex portion 100 Rack and pinion type steering device

Claims (1)

Rack and pinion type steering equipped with a pinion shaft formed with pinion teeth, a rack shaft formed with rack teeth meshing with the pinion teeth, and a rack housing for guiding the rack shaft so as to be movable in the axial direction an apparatus,
The rack housing has a first attachment portion and a second attachment portion that are made of metal and attached to a vehicle body, and a pipe-like cylinder portion that connects the first attachment portion and the second attachment portion to each other,
The cylindrical portion is a laminate formed by laminating at least two layers of fiber reinforced plastic sheets , and the fiber angles of the reinforcing fibers included in one of the two adjacent layers and the other layer are different from each other. And
The outer surface of the cylindrical connecting portion formed on the first mounting portion and the second mounting portion and connected to the cylindrical portion protrudes radially outward, and the thickness of the two-layer sheet of the cylindrical portion A plurality of engaging projections having the above length are formed ,
The axial ends of the cylindrical part engage with the connecting part in a state where the engaging convex part penetrates at least the innermost two layers of sheets ,
A rack and pinion type steering device.

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