Electric power steering

Abstract

In the present invention, a case (34) accommodating a controller for controlling a motor that operates a steering mechanism of a vehicle (10) is provided with at least one of: a thin-walled part (34b) which is thinner than other parts of the case (34) and which extends along an attachment part of a harness connector (36) to which wire harnesses (32a, 32b, 32c) for supplying power to the motor are connected, and along at least one of the width direction and the front-rear direction of the vehicle (10); and a starting point part which is provided on the vehicle rear side of the attachment part of the harness connector (36), and which serves as a starting point for fracture of the case (34) when a force toward the front of the vehicle (10) is applied thereto.

Description

Electric power steering

[0008] ,

[0001] The present invention relates to an electric power steering.

[0002] There is known an electric power steering that outputs an auxiliary torque for assisting the steering of a steering wheel from a motor and transmits the auxiliary torque to a rack shaft via a belt drive mechanism (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2019-21604

[0004] In the above prior art, when the vehicle has a frontal collision, the connector unit of the motor contacts a dash panel arranged behind the vehicle from the electric power steering, and there is a problem that the wire harness comes off from the connector unit.

[0005] The problem to be solved by the present invention is to provide an electric power steering that can suppress the wire harness from coming off from the harness connector when the vehicle has a frontal collision.

[0006] ​​​​​​This is a front view showing a vehicle equipped with electric power steering according to one embodiment of the present invention. This is a cross-sectional view along the line A-A in Figure 1. This is a cross-sectional view along the line B-B in Figure 2. This is an enlarged side view showing an example of the case in Figure 3. This is an enlarged side view showing another example of the case in Figure 3. This is a perspective view showing electric power steering according to another embodiment of the present invention. This is an enlarged side view showing the position where the case in Figure 3 breaks when the vehicle in Figure 1 is involved in a frontal collision.

[0009] Embodiments of the present invention will be described below with reference to the drawings. In the drawings, "front" refers to the front of the vehicle, "rear" refers to the rear of the vehicle, "right" refers to the right side of the vehicle, "left" refers to the left side of the vehicle, "up" refers to the top of the vehicle, and "down" refers to the bottom of the vehicle. The front-rear direction of the vehicle is also simply referred to as the front-rear direction, the left-right direction of the vehicle is also referred to as the width direction, and the up-down direction of the vehicle is also referred to as the height direction.

[0010] In the following explanation, the front of the vehicle, the rear of the vehicle, the right side of the vehicle, the left side of the vehicle, the top of the vehicle, and the bottom of the vehicle correspond to the front, back, right, left, top, and bottom sides of the vehicle, respectively. The right and / or left sides of the vehicle are also referred to as the vehicle sides.

[0011] Furthermore, the front of the vehicle's power source (e.g., the engine) is defined as the front side, and viewing the vehicle from the front of the power source is called a front view of the vehicle. Similarly, viewing the vehicle from the rear is called a rear view of the vehicle, viewing the vehicle from the right or left side is called a side view of the vehicle, viewing the vehicle from above is called a top view of the vehicle, and viewing the vehicle from below is called a bottom view of the vehicle.

[0012] [Configuration of Electric Power Steering] Figure 1 is a front view showing a vehicle equipped with electric power steering according to one embodiment of the present invention (hereinafter also referred to as this embodiment). The vehicle according to this embodiment is not particularly limited as long as it can be equipped with the electric power steering of this embodiment. The vehicle 10 shown in Figure 1 is a vehicle equipped with a motor, which is a drive source, at the front of the vehicle and drives at least the front wheels.

[0013] Figure 2 is a cross-sectional view along the line A-A in Figure 1, and is a cross-sectional view of the main parts showing the electric power steering and related components of this embodiment. As shown in Figure 2, the vehicle 10 includes front side members 11a, 11b, a dash panel 12, a front suspension member 13, suspension arms 14a, 14b, drive shafts 15a, 15b, a motor 16, hubs 17a, 17b, electric power steering 18, a case 19, a steering shaft 20, and tie rods 21a, 21b.

[0014] The front side members 11a and 11b are components that support drive sources such as engines and motors, auxiliary equipment for drive sources, and the body shell, and extend in the longitudinal direction at a position forward of the passenger compartment of the vehicle 10. The front side members 11a and 11b are manufactured, for example, by joining two steel plates that have been press-formed into a U-shape (or C-shape) cross-section by spot welding or the like. The shape of the front side members 11a and 11b is not particularly limited as long as it can adequately support the drive sources and the like.

[0015] The dash panel 12 is a bulkhead plate that separates the engine compartment and the passenger compartment at the front of the vehicle, and is manufactured, for example, by press-forming a steel plate. The shape of the dash panel 12 is not particularly limited, as long as it corresponds to the shape of the passenger compartment and can adequately separate the engine compartment and the passenger compartment.

[0016] The front suspension member 13 is manufactured, for example, by joining press-formed rolled steel plate members by arc welding, and supports the drive shafts 15a and 15b via suspension arms 14a and 14b. The suspension arms 14a and 14b are, for example, cast or forged products of steel, aluminum alloy, etc. The front suspension member 13 is attached to the front side members 11a and 11b by bolt fastening or the like.

[0017] The drive shafts 15a and 15b are manufactured, for example, by forging or machining a cylindrical steel member, and transmit power from the motor 16, which is the drive source of the vehicle 10, to the front wheels supported by the hubs 17a and 17b. Specifically, the drive shaft 15a transmits power to the left front wheel supported by the hub 17a on the left side of the vehicle, and the drive shaft 15b transmits power to the right front wheel supported by the hub 17b on the right side of the vehicle. The motor 16 is supported by the front side members 11a and 11b. The hubs 17a and 17b are, for example, cast or forged steel products.

[0018] Vehicle 10 is equipped with an electric power steering system 18 located behind the drive shafts 15a and 15b that drive the front wheels. The electric power steering system 18 is a group of devices that assist the driver's steering operation by operating the steering mechanism with a motor different from the motor 16 that is the drive source. The electric power steering system 18 is mounted in a case 19 that houses the steering rack. The electric power steering system 18 detects the torque input to the steering wheel (not shown) using a torque sensor (not shown) attached to the steering shaft 20, and operates the motor according to the detected torque to move the steering rack in the width direction.

[0019] The ends of the steering rack are connected to one end of tie rods 21a and 21b via ball joints or the like, and the other ends of tie rods 21a and 21b are connected to suspension arms 14a and 14b via ball joints or the like. Hub 17a is supported by suspension arm 14a so as to be able to rotate around the height direction as the axis of rotation, and hub 17b is supported by suspension arm 14b so as to be able to rotate around the height direction as the axis of rotation. Therefore, when the steering rack moves in the width direction, the hubs 17a and 17b rotate around the height direction as the axis of rotation via tie rods 21a and 21b, and the direction of travel of the vehicle 10 can be changed. The tie rods 21a and 21b are cast or forged products of steel, aluminum alloy, etc.

[0020] The lower part of Figure 2 shows a magnified view of the area around the electric power steering 18. As shown in Figure 2, the electric power steering 18 comprises a case 31, wire harnesses 32a, 32b, 32c, connectors 33a, 33b, 33c, case 34, and cover 35.

[0021] Case 31 houses a motor (hereinafter also referred to as the steering motor) that operates the steering mechanism of the vehicle 10 and is fixed to case 19. Case 31 is a casting or forging of steel, aluminum alloy, or the like. The shape of case 31 is not particularly limited as long as it can accommodate the steering motor, which is the power source of the electric power steering 18. Case 31 may be integrated with case 19.

[0022] The steering motor housed in case 31 supplies power to operate the electric power steering 18. The steering mechanism operated by the steering motor is a component that rotates the steering wheels (i.e., the front wheels) of the vehicle 10 with the height direction as the axis of rotation, thereby changing the direction of travel of the vehicle 10. Examples of the steering mechanism include the steering shaft 20 and the steering rack housed in case 19. Furthermore, if the power of the steering motor is transmitted to the steering rack by a pinion meshed with the steering rack, the pinion is included in the steering mechanism, and if the power of the steering motor is transmitted to the steering rack by a belt drive mechanism, the belt is included in the steering mechanism.

[0023] The wire harnesses 32a, 32b, and 32c supply power to the steering motor. For example, wire harness 32a supplies power to the controller that controls the steering motor, wire harness 32b supplies power to the rotor coil of the steering motor, and wire harness 32c supplies backup power to the steering motor and its controller. The wire harnesses 32a, 32b, and 32c are made by bundling multiple wires covered with insulating material using cable ties or the like, and terminals are provided at both ends for electrical connection to other circuits or elements.

[0024] Connectors 33a, 33b, and 33c are housings that hold terminals provided at the ends of wire harnesses 32a, 32b, and 32c. Connectors 33a, 33b, and 33c are manufactured, for example, by injection molding of resin materials such as polyacetal (POM) or polybutylene terephthalate (PBT). Connectors 33a, 33b, and 33c have shapes corresponding to the shape of the harness connector 36, which will be described later, and are inserted into the harness connector 36.

[0025] Case 34 houses a controller (hereinafter also simply referred to as the controller) that controls the steering motor. Case 34 has a box-like shape and is manufactured by press forming of steel plate or casting of aluminum alloy. The controller controls the operation of the steering motor according to control signals transmitted via wire harnesses 32a, 32b, and 32c.

[0026] The cover 35 is a plate-shaped member that closes the opening of the case 34, and is joined to the case 34 by means of adhesive bonding or fastening with bolts. The cover 35 is manufactured, for example, by injection molding of a resin material such as polybutylene terephthalate (PBT).

[0027] Figure 3 is a cross-sectional view along the line B-B in Figure 2, showing the positional relationship between the electric power steering 18 and the components arranged around it.

[0028] The harness connector 36 shown in Figure 3 is a housing that holds the connectors 33a, 33b, and 33c of the wire harnesses 32a, 32b, and 32c, and is attached to the case 34 by bolt fastening or the like. The harness connector 36 is manufactured by injection molding of a resin material such as polyacetal (POM) or polybutylene terephthalate (PBT), and has a shape that can properly hold the inserted connectors 33a, 33b, and 33c.

[0029] The harness connector 36 has terminals that are electrically connected to terminals provided at the ends of the wire harnesses 32a, 32b, and 32c. The terminals of the harness connector 36 are electrically connected to at least one of the steering motor and the controller. As a result, a power source such as a battery (not shown) is electrically connected to the steering motor and the controller via the wire harnesses 32a, 32b, 32c and the harness connector 36.

[0030] As shown in Figures 2 and 3, the electric power steering 18 is positioned in front of the dashboard panel 12. For example, the electric power steering 18 is positioned in front of the dashboard panel 12 and behind the drive shafts 15a, 15b and the motor 16. Alternatively, the electric power steering 18 may be positioned between the dashboard panel 12 and the drive shafts 15a, 15b in the front-rear direction.

[0031] Furthermore, at least a portion of the electric power steering 18 (or the components comprising the electric power steering 18) overlaps with at least one of the drive shafts 15a, 15b and the motor 16 when the vehicle 10 is viewed from the front. For example, if the vehicle 10 is involved in a frontal collision and the drive shafts 15a and motor 16 move to the rear of the vehicle, the drive shafts 15a and motor 16 will interfere with (e.g., contact with) the electric power steering 18, causing the electric power steering 18 to move to the rear of the vehicle.

[0032] Figures 4 and 5 are enlarged side views (right side views) of the case 34 with the harness connector 36 removed. In the case 34 shown in Figures 4 and 5, the controller 37 is housed in the upper part of the case 34, and the lower part of the case 34 is integrated with the case 31. Furthermore, the case 34 in this embodiment has a part that is relatively more prone to breakage than other parts of the case 34.

[0033] For example, the case 34 of this embodiment is provided with a thin-walled portion that is thinner than the rest of the case 34. The thin-walled portion extends along the mounting portion of the harness connector 36 (hereinafter also simply referred to as the mounting portion) in at least one direction, either in the width direction or the front-rear direction. As an example, the case 34 shown in Figure 4 is provided with a protrusion 34a that projects to the right of the vehicle as a mounting portion. The protrusion 34a engages with a corresponding recess provided on the harness connector 36. In the case 34 shown in Figure 4, a thin-walled portion 34b, indicated by a dashed line, extends in the front-rear direction along the protrusion 34a provided on the upper part of the case 34. The thin-walled portion 34b is provided, for example, at least one of a position above the protrusion 34a on the vehicle and a position below the protrusion 34a on the vehicle.

[0034] The thickness of the thin-walled portion 34b of the case 34 can be set to an appropriate value within a range that allows the case 34 to be properly formed. For example, the thickness of the thin-walled portion 34b of the case 34 is 0.5 to 3 mm thinner than the thickness of the parts of the case 34 other than the thin-walled portion 34b. Alternatively, the thickness of the thin-walled portion 34b of the case 34 may be 10 to 90% of the thickness of the parts of the case 34 other than the thin-walled portion 34b. Note that the mounting portion is not limited to the protrusion 34a shown in Figure 4, but also includes the bolt fastening portion between the case 34 and the harness connector 36, the adhesive portion between the case 34 and the harness connector 36, etc.

[0035] Furthermore, the case 34 of this embodiment may be provided with a starting point portion that serves as the starting point for fracture of the case 34 when a forward force is applied to the vehicle 10. The starting point portion is provided on the rear side of the mounting portion of the harness connector 36, for example, at the end of the case 34 that is on the vehicle side of the mounting portion of the harness connector 36. The starting point portion may be, for example, a notch provided at the end of the case 34, or a hole provided near the end of the case 34. As an example, the case 34 shown in Figure 5 has a notch 34c, which is the starting point portion, at the end of the case 34 that is on the vehicle side of the convex portion 34a at the top of the case 34.

[0036] The size of the notch 34c can be set to an appropriate size within the range in which the case 34 will break from the notch 34c in the event of a frontal collision with the vehicle 10. Similarly, if the starting point is a hole, the size of the hole can be set to an appropriate size within the range in which the case 34 will break from the periphery of the hole in the event of a frontal collision with the vehicle 10. The notch 34c is provided, for example, at least one of a position above the convex portion 34a and a position below the convex portion 34a.

[0037] Figure 6 is a perspective view showing an electric power steering system 18a according to another embodiment of the present invention. As shown in Figure 6, the electric power steering system 18a differs from the electric power steering system 18 in that it includes a protector 38.

[0038] The protector 38 prevents the drive shafts 15a and 15b from contacting the harness connector 36 in the event of a frontal collision of the vehicle 10. As shown in Figure 6, the protector 38 is positioned in front of the harness connector 36. The protector 38 is also positioned so as to overlap with the harness connector 36 when the vehicle 10 is viewed from the front. A predetermined gap is provided between the protector 38 and the case 34. This predetermined gap can be set to an appropriate distance within a range that prevents the case 34, if broken in the event of a frontal collision of the vehicle 10, from moving forward of the protector 38, for example, 10 to 30 mm.

[0039] The protector 38 has a suitable shape within a range that allows it to transmit the force input from the drive shafts 15a and 15b to the case 31, and is made of a material such as steel or aluminum alloy. The protector 38 is manufactured, for example, by joining together members made by press-forming steel plates by welding. Alternatively, the protector 38 may be manufactured by forging a steel workpiece. The protector 38 may be positioned so as to overlap with the case 34 or cover 35 when the vehicle 10 is viewed from the front.

[0040] Furthermore, the protector 38 may include a plate that restricts the movement of the case 34 when a force is applied to the case 34 in the right-front or left-front direction of the vehicle 10. This plate may be an L-shaped plate having a first portion extending from the protector 38 to the right or left of the vehicle, and a second portion extending from the tip of the first portion to the rear of the vehicle. As an example, the protector 38 shown in Figure 6 includes an L-shaped plate 39 having a first portion 39a extending from the protector 38 to the left of the vehicle, and a second portion 39b extending from the tip of the first portion 39a to the rear of the vehicle.

[0041] [Function of the thin-walled portion and the starting portion] Figure 7 is an enlarged side view (right side view) showing the position where the case 34 breaks when the vehicle 10 is involved in a frontal collision. In the example shown in Figure 7, the vehicle 10 is involved in a frontal collision, and the drive shaft 15a and motor 16, which have moved to the rear of the vehicle, come into contact with the case 31, causing the case 34 to move to the rear of the vehicle together with the case 31. Furthermore, the case 34 is provided with the thin-walled portion 34b shown in Figure 4.

[0042] In this case, as shown on the left side of Figure 7, case 34 moves together with case 31 toward the rear of the vehicle (in the direction of arrow A1) and comes into contact with the dash panel 12. A forward force F is applied to case 34 from the dash panel 12 upon contact with the vehicle 10. If the applied force F is strong enough to break the thin-walled portion 34b in the longitudinal direction, case 34 will break at the break position X shown on the left side of Figure 7.

[0043] If the cover 35 breaks in the same way as the case 34, the case 34 will separate into an upper part 34x, which is the upper part of the case 34 and to which the harness connector 36 is attached and which houses the controller 37, and a lower part 34y, which is integrated with the case 31, as shown on the right side of Figure 7. Part 34x moves towards the front of the vehicle (in the direction of arrow A2) on the opposite side of the dash panel 12 and does not come into contact with the dash panel 12 again, thus preventing the wire harnesses 32a, 32b, and 32c from coming off the harness connector 36. The same effect is achieved even if the case 34 is provided with a notch 34c as shown in Figure 5, as the case 34 will break at the break position X shown in Figure 7.

[0044] The movement of the partial 34x in the vehicle front direction (the direction of arrow A2) is restricted by the protector 38 (and the first part 39a of the plate 39) as shown on the right side of FIG. 7. That is, the partial 34x that has moved in the vehicle front direction contacts the protector 38 and the first part 39a and does not move further in the vehicle front direction from the protector 38 and the plate 39, so that the wire harnesses 32a, 32b, 32c are further prevented from detaching from the harness connector 36. Since an interval D corresponding to a predetermined interval is provided between the protector 38 and the case 34 (partial 34y), the partial 34x can move by a distance such that it does not contact the dash panel 12 again.

[0045] Further, when a force in the left front direction of the vehicle indicated by arrow A3 in FIG. 6 is input from the dash panel 12, the partial 34x moves in the left front direction of the vehicle. In this case, the movement of the partial 34x in the left direction of the vehicle is restricted by the second part 39b of the plate 39. That is, the partial 34x that has moved in the left direction of the vehicle contacts the second part 39b and does not move further in the left direction of the vehicle from the second part 39b, so that the wire harnesses 32a, 32b, 32c are further prevented from detaching from the harness connector 36.

[0046] [Embodiment of the Invention] According to the present embodiment, there is provided an electric power steering 18 including a case 34 disposed in front of the dash panel of the vehicle 10 and housing a controller 37 for controlling a motor that operates a steering mechanism of the vehicle 10, and a harness connector 36 attached to the case 34 and to which wire harnesses connected to supply electric power to the motor are connected. The case 34 has a thin-walled part 34b extending along at least one of the width direction and the front-rear direction of the vehicle 10 along the attachment part of the harness connector 36 and having a thickness thinner than other parts of the case 34, and at least one of a starting point part provided on the rear side of the vehicle of the attachment part and serving as a starting point of breakage of the case 34 when a force in the forward direction of the vehicle 10 is input. Thereby, it is possible to prevent the wire harnesses 32a, 32b, 32c from detaching from the harness connector 36 when the vehicle 1 is in a frontal collision.

[0047] In the electric power steering 18 of the present embodiment, a protector 38 is further provided in front of the vehicle from the harness connector 36 and at a position overlapping the harness connector 36 when the vehicle 10 is viewed from the front. Thereby, the movement amount of the broken harness connector 36 can be restricted.

[0048] In the electric power steering 18 of the present embodiment, the protector 38 includes a plate 39 that restricts the movement of the case 34 when a force in the right front direction or the left front direction of the vehicle 10 is input to the case 34. Thereby, the movement amount of the broken case 34 can be restricted.

[0049] In the electric power steering 18 of the present embodiment, the plate 39 is an L-shaped plate 39 having a first portion 39a extending from the protector 38 to the right or left of the vehicle and a second portion 39b extending rearward of the vehicle from the tip of the first portion 39a. Thereby, the movement amount of the broken case 34 can be restricted more.

[0050] 10... Vehicle 11a, 11b... Front side member 12... Dash panel 13... Front suspension member 14a, 14b... Suspension arm 15a, 15b... Drive shaft 16... Motor 17a, 17b... Hub 18, 18a... Electric power steering 19... Case 20... Steering shaft 21a, 21b... Tie rod 31... Case 32a, 32b, 32c... Wire harness 33a, 33b, 33c... Connector 34... Case 34x, 34y... Portion 34a... Convex portion (attachment portion) 34b... Thin-walled portion 34c... Notch (starting point portion) 35... Cover 36... Harness connector 37... Controller 38... Protector 39... Plate 39a... First portion 39b... Second portion A1, A2, A3... Arrow D... Interval F... Force X... Breaking position

Claims

1. An electric power steering system comprising: a case located in front of the vehicle's dashboard panel and housing a controller for controlling a motor that operates the vehicle's steering mechanism; and a harness connector attached to the case and connected to a wire harness that supplies power to the motor, wherein the case is provided with at least one of the following: a thin-walled portion extending along the mounting portion of the harness connector in at least one direction of the vehicle's width and longitudinal directions and having a thinner thickness than the rest of the case; and a starting portion provided on the rear side of the mounting portion of the vehicle and serving as the starting point for fracture of the case when a forward force is applied to the vehicle.

2. The electric power steering according to claim 1, further comprising a protector positioned in front of the harness connector and overlapping with the harness connector when the vehicle is viewed from the front.

3. The electric power steering according to claim 2, wherein the protector includes a plate that restricts the movement of the case when a force is applied to the case in the right front or left front direction of the vehicle.

4. The electric power steering according to claim 3, wherein the plate is an L-shaped plate having a first portion extending from the protector to the right or left of the vehicle, and a second portion extending from the tip of the first portion to the rear of the vehicle.

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