Rack and electric power steering system comprising same

Abstract

The utility model relates to the technical field of power-assisted steering systems, in particular to a rack and an electric power-assisted steering system comprising the same, the rack comprises a rod body, a tooth part is arranged on the outer surface of the rod body, a through hole is formed in the rod body, and an annular groove is formed in the outer surface of the rod body. According to the gear-assisted steering system, the problem that the light weight degree of an existing gear-assisted steering system is insufficient is solved, the weight of the rack is reduced, the light weight degree of the rack is improved, and a greater contribution can be made to the light weight of the gear-assisted electric steering system.

Description

TECHNICAL FIELD

[0001] The utility model relates to power assisted steering system technical field, more specifically, relate to a rack and contain its electric power assisted steering system. BACKGROUND

[0002] Electric power assisted steering system (Electric Power Steering, EPS for short) is the main steering system of passenger cars and part of small commercial vehicles. According to the different assembly positions of the power-assisted motor, EPS can be divided into column power-assisted type (C-EPS for short), pinion power-assisted type (P-EPS for short), rack power-assisted type (R-EPS for short) and double pinion power-assisted type (DP-EPS for short) four kinds. New energy electric vehicles mostly use P-EPS and DP-EPS gear power-assisted steering system, which has compact structure, light weight and high transmission efficiency, and is suitable for lightweight and small design.

[0003] With the increase of new energy electric vehicles, the weight of the battery and the vehicle increases, so the overall weight of the vehicle increases, and the driving distance relative to the battery capacity becomes shorter, so the lightweight of the parts is more needed, and the electric power assisted steering system also needs to be lightweight, how to optimize the structure design and reduce the weight of the parts, which is a long-term and constantly improved production problem. UTILITY MODEL CONTENTS

[0004] The utility model aims at overcoming the problem of insufficient lightweight degree of the existing gear power-assisted steering system, and provides a rack and an electric power assisted steering system containing the same. The utility model reduces the weight of the rack, improves the lightweight degree of the rack, and can make greater contribution to the lightweight of the electric power assisted steering system of the gear power-assisted type.

[0005] To solve the above technical problems, the utility model adopts the technical scheme of:

[0006] A rack, comprising a rod body, the outer surface of the rod body is provided with a tooth part, a through hole is formed in the inner part of the rod body, and an annular groove is formed on the outer surface of the rod body.

[0007] The utility model discloses a kind of weight-reducing rack, comprising rod body and tooth part, the rod body is provided with two kinds of weight-reducing parts on the rod body, one is internal through hole, one is annular groove for weight reduction of outer surface;Tooth part is arranged on outer surface, the shaft diameter of rack tooth part cannot be changed, but since tooth part only receives the force of rack axial direction, so it is not necessary that each place shaft diameter is same with tooth part, thus compared with the shaft diameter of tooth part, other positions can reduce diameter, and it does not affect the use of rack;On the one hand, annular groove is formed by reducing shaft diameter, on the other hand, internal through hole is provided in rack to realize hollow, to reduce the weight of rack, improve the degree of rack lightweight, can make greater contribution for gear power-assisted electric power steering system lightweight.

[0008] Further, the cross section of the annular groove is trapezoidal, and the bottom width of the annular groove is less than the opening width of the annular groove.

[0009] The annular groove with trapezoidal cross section can have a good transition slope on the side wall, which can reduce stress concentration and improve the fatigue strength and service life of the part. Meanwhile, a chamfer can be arranged at the junction of the slope and the slope bottom or top, further reducing stress concentration.

[0010] Further, the included angle between the side wall and the bottom of the annular groove is in the range of 105°-135°. Due to the length limitation of the rack, if the inclination angle of the transition slope is too large, the depth of the annular groove is not large, and the weight reduction effect is not large. If the inclination angle of the transition slope is too small, stress concentration is easily formed. After continuous testing, when the included angle is in the range of 105°-135°, the rack can better balance the weight reduction effect and torsional strength.

[0011] Further, the depth of the annular groove is 10%-15% of the diameter of the rod body. The depth of the annular groove needs to consider whether the overall torsional strength of the rack after slotting can meet the transmission requirements, so after continuous testing, the depth of the annular groove is preferably 10%-15% of the diameter of the rod body, taking the commonly used rack specifications of the gear power-assisted type as the design standard.

[0012] Further, the through hole penetrates the rod body along the axis of the rod body.

[0013] Further, the wall thickness L between the through hole and the tooth bottom of the tooth part is greater than or equal to 2 mm. Limiting the minimum wall thickness can ensure the feasibility of the manufacturing process and the fatigue strength of the material.

[0014] As a preferred scheme, the tooth part includes two, the two tooth parts are distributed at both ends of the rod body, and the annular groove is located between the two tooth parts.

[0015] Further, the annular groove is located in the middle of the rod body, and the opening width of the annular groove is 50%-80% of the distance between the two tooth parts.

[0016] It should be noted that when the number of teeth is two, the rack is a double pinion assisted steering system, and the two teeth of the rack are symmetrically arranged on the outer side wall of the two ends of the rod body, at this time the annular groove is located in the middle of the two teeth, and both sides of the teeth have transmission movement, therefore the torque transmission strength of the connection in the middle needs to be considered, the opening distance of the annular groove is controlled to be 50% to 80% of the distance between the teeth, and good lightweight effect is achieved.

[0017] As another preferred solution, the tooth part is one, and the tooth part and the annular groove are located on the two sides of the rod body.

[0018] It should be noted that when the number of teeth is one, the rack is a single pinion assisted steering system, and the tooth part and the annular groove of the rack are located on the two sides, the opening distance of the annular groove does not need to be specially controlled, and the transmission torque strength requirement is not easily affected, therefore a suitable length of the annular groove can be opened according to the length of the rack, so that the lightweight effect is best.

[0019] The utility model also provides a kind of electric power assisted steering system, including rack as described above.It should be noted that when the number of teeth is two, it is a double pinion assisted steering system, and when the number of teeth is one, it is a single pinion assisted steering system.

[0020] Compared with the prior art, the utility model has the beneficial effects that:

[0021] The utility model realizes lightweight by setting two weight-reducing parts on the rod body of rack, one is internal through hole, and the other is annular groove for weight reduction of outer surface;Tooth part is arranged on outer surface, and the shaft diameter of rack tooth part cannot be changed, but since tooth part only bears axial force of rack, the shaft diameter of each part does not need to be the same as that of tooth part, so compared with the shaft diameter of tooth part, the diameter of other positions can be reduced, without affecting the use of rack;On the one hand, annular groove is formed by reducing shaft diameter, and on the other hand, internal through hole is arranged in rack to realize hollow, so as to reduce the weight of rack, improve the degree of lightweight of rack, and make greater contribution to lightweight of electric power assisted steering system. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a structure schematic view of the utility model embodiment 1.

[0023] Figure 2 It is Figure 1 a sectional view schematic view;

[0024] Figure 3 It is Figure 2 enlarged view of A in

[0025] Figure 4 It is a structure schematic view of the utility model embodiment 4.

[0026] Figure 5 Figure 4 is a structural schematic view of another aspect of the embodiment 4 of the present application.

[0027] The illustration marks are explained as follows:

[0028] 1-rod body, 2-tooth part, 3-through hole, 4-annular groove. DETAILED DESCRIPTION

[0029] The present application will be further described in conjunction with specific embodiments. The drawings are only used for exemplary description, and the representation is only a schematic diagram, not a physical diagram, and cannot be understood as a limitation on the present patent; in order to better illustrate the embodiments of the present application, some components of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures in the drawings and their descriptions may be omitted.

[0030] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it is understood that if the terms "upper", "lower", "left", "right" and the like indicate the orientation or positional relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the positional relationship described in the drawings is only used for exemplary description, and cannot be understood as a limitation on the present patent, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0031] Embodiment 1

[0032] As Figures 1 to 3 shown is the first embodiment of the present application, a rack, comprising a rod body 1, the outer surface of the rod body 1 is provided with a tooth part 2, the inside of the rod body 1 is provided with a through hole 3, and the outer surface of the rod body 1 is provided with an annular groove 4.

[0033] As Figure 3 shown, the cross section of the annular groove 4 is trapezoidal, and the bottom width of the annular groove 4 is less than the opening width of the annular groove 4.

[0034] The trapezoidal annular groove 4 can have a good transition slope on the side wall, the transition slope can reduce stress concentration, and improve the fatigue strength and service life of the part.

[0035] In the embodiment, the junction of the slope of the annular groove 4 and the slope bottom or slope top is provided with a chamfer, further reducing the stress concentration.

[0036] In this embodiment, the included angle between the sidewall and bottom of the annular groove 4 is 120°. Due to the length limitation of the rack, if the inclination angle of the transition slope is too large, the depth of the annular groove 4 will be small, and the weight reduction effect will be small. If the inclination angle of the transition slope is too small, stress concentration is likely to occur. Controlling the included angle range allows the rack to better balance the weight reduction effect and torsional strength.

[0037] In this embodiment, the depth of the annular groove 4 is 12% of the diameter of the rod 1. The depth of the annular groove 4 needs to take into account whether the overall torsional strength of the rack after slotting can meet the transmission requirements. Therefore, after continuous testing, the rack specifications commonly used in gear-assisted systems are used as the design standard, and the depth of the annular groove 4 is 12% of the diameter of the rod 1.

[0038] like Figure 2 As shown, through hole 3 extends through rod 1 along the axis of rod 1.

[0039] like Figure 3 As shown, the wall thickness L between the through hole 3 and the tooth root of the tooth 2 is greater than or equal to 2 mm.

[0040] In this embodiment, there is one tooth 2, and the tooth 2 and the annular groove 4 are located on both sides of the rod 1, respectively.

[0041] It should be noted that when there is only one tooth 2, it is a rack of a single pinion power steering system. The tooth 2 and the annular groove 4 are located on both sides of the rack. The opening distance of the annular groove 4 does not need to be specially controlled and is not likely to affect its transmission torque strength requirements. Therefore, the annular groove 4 of appropriate length can be opened according to the rack length to achieve the best weight reduction effect.

[0042] The advantage of this embodiment is that it achieves weight reduction by setting two weight-reducing parts on the rack body 1: an internal through hole 3 and an annular groove 4 for weight reduction on the outer surface. The tooth 2 is located on the outer surface, and the shaft diameter of the rack tooth 2 cannot be changed. However, since the tooth 2 only bears the axial force of the rack, it is not necessary for the shaft diameter to be the same as that of the tooth 2 at all other locations. Therefore, the diameter at other locations can be reduced compared to that of the tooth 2 without affecting the use of the rack. On the one hand, the annular groove 4 is formed by reducing the shaft diameter, and on the other hand, the rack is hollowed out by opening the through hole 3 inside, thereby reducing the weight of the rack and improving the degree of rack weight reduction. This can make a greater contribution to the weight reduction of gear-assisted electric steering systems.

[0043] Example 2

[0044] This embodiment is similar to Embodiment 1, except that:

[0045] In the embodiment, the included angle of the side wall and the bottom of the annular groove 4 ranges from 105°. Due to the length limitation of the rack, if the inclination angle of the transition slope is too large, the depth of the annular groove 4 is not large, and the weight reduction effect is not large. If the inclination angle of the transition slope is too small, stress concentration is easily formed. Controlling the included angle range can make the rack better balance the weight reduction effect and the torsional strength.

[0046] In the embodiment, the depth of the annular groove 4 is 10% of the diameter of the rod body 1. The depth of the annular groove 4 needs to consider whether the torsional strength of the rack as a whole after the groove is opened can meet the transmission demand. Therefore, after continuous testing, the depth of the annular groove 4 is 10% of the diameter of the rod body 1, which is used as the design standard of the commonly used rack of the gear-assisted type at present.

[0047] The other structures and principles of the embodiment are the same as those of embodiment 1.

[0048] Embodiment 3

[0049] The embodiment is similar to embodiment 1, and the difference is that:

[0050] In the embodiment, the included angle of the side wall and the bottom of the annular groove 4 ranges from 135°. Due to the length limitation of the rack, if the inclination angle of the transition slope is too large, the depth of the annular groove 4 is not large, and the weight reduction effect is not large. If the inclination angle of the transition slope is too small, stress concentration is easily formed. Controlling the included angle range can make the rack better balance the weight reduction effect and the torsional strength.

[0051] In the embodiment, the depth of the annular groove 4 is 15% of the diameter of the rod body 1. The depth of the annular groove 4 needs to consider whether the torsional strength of the rack as a whole after the groove is opened can meet the transmission demand. Therefore, after continuous testing, the depth of the annular groove 4 is 15% of the diameter of the rod body 1, which is used as the design standard of the commonly used rack of the gear-assisted type at present.

[0052] The other structures and principles of the embodiment are the same as those of embodiment 1.

[0053] Embodiment 4

[0054] The embodiment is similar to embodiment 1, and the difference is that:

[0055] As shown in Figure 4 and Figure 5 , the tooth part 2 includes two, and the two tooth parts 2 are distributed at the two ends of the rod body 1. The annular groove 4 is located in the middle of the two tooth parts 2.

[0056] As shown in Figure 4 and Figure 5 , the annular groove 4 is located in the middle of the rod body 1, and the opening width of the annular groove 4 is 60% of the distance between the two tooth parts 2.

[0057] It should be noted that when the number of tooth parts 2 is two, the rack is a double pinion assisted steering system, the two tooth parts 2 of the rack are symmetrically arranged on the outer side walls of the two ends of the rod body 1, at this time the annular groove 4 is located in the middle of the two tooth parts 2, and both sides of the tooth part 2 have transmission movement, therefore the connection in the middle needs to consider the torque transmission strength, so as to have a good lightweight effect.

[0058] The other structures and principles of the embodiment are the same as those of embodiment 1.

[0059] Embodiment 5

[0060] The embodiment provides an electric power assisted steering system, which comprises the rack of embodiment 1, the tooth part 2 comprises two, the two tooth parts 2 are distributed on the two ends of the rod body 1, and the annular groove 4 is located in the middle of the two tooth parts 2, when the number of tooth parts 2 is two, the electric power assisted steering system is a double pinion assisted steering system.

[0061] Embodiment 6

[0062] The embodiment provides an electric power assisted steering system, which comprises the rack of embodiment 4, the tooth part 2 is one, and the tooth part 2 and the annular groove 4 are located on the two sides of the rod body 1 respectively. When the number of tooth parts 2 is one, the electric power assisted steering system is a single pinion assisted steering system.

[0063] Obviously, the above embodiments of the utility model are only examples for clearly illustrating the utility model, and are not the limitation of the embodiments of the utility model. For ordinary skilled in the art, on the basis of the above description, other different forms of changes or changes can be made. Here, it is not necessary and impossible to exhaust all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principle of the utility model should be included in the protection scope of the utility model claim.

Claims

1. A rack characterized by, The rod body (1) is provided with a tooth portion (2) on its outer surface, and a through hole (3) is formed in the interior of the rod body (1), and an annular groove (4) is formed on the outer surface of the rod body (1).

2. A rack according to claim 1, wherein, The cross section of the annular groove (4) is trapezoidal, and the bottom width of the annular groove (4) is smaller than the opening width of the annular groove (4).

3. A rack according to claim 2, wherein, The included angle of the side wall and the bottom of the annular groove (4) ranges from 105° to 135°.

4. A rack according to claim 3, wherein, The depth of the annular groove (4) is 10% to 15% of the diameter of the rod body (1).

5. A rack according to claim 1, wherein, The through hole (3) penetrates the rod body (1) along the axis of the rod body (1).

6. A rack according to claim 1, wherein, The wall thickness L between the through hole (3) and the tooth bottom of the tooth portion (2) is greater than or equal to 2 mm.

7. A rack according to claim 1, wherein, The tooth portion (2) includes two tooth portions (2) distributed at both ends of the rod body (1), and the annular groove (4) is located between the two tooth portions (2).

8. The rack according to claim 7, wherein, The annular groove (4) is located in the middle of the rod body (1), and the opening width of the annular groove (4) is 50% to 80% of the distance between the two tooth portions (2).

9. A rack according to claim 1, wherein, The tooth portion (2) is one, and the tooth portion (2) and the annular groove (4) are located on both sides of the rod body (1), respectively.

10. An electric power assisted steering system characterised in that, The rack includes the rack according to any one of claims 8 or 9.

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