Asymmetric efficiency transmission mechanism, motor assembly, steer-by-wire system and vehicle

Abstract

The present application provides an asymmetric efficiency transmission mechanism, a motor assembly, a wire-controlled steering system and a vehicle, which are applied to the field of asymmetric efficiency transmission technology. The transmission mechanism has a first transmission path and a second transmission path connected in parallel, the first transmission path is configured to have a high forward transmission efficiency and includes a first drive-side shaft component and a first load-side shaft component; the second transmission path is configured to have a low reverse transmission efficiency and includes a second drive-side shaft component and a second load-side shaft component, wherein the first drive-side shaft component and the second drive-side shaft component are transmission-connected, the transmission mechanism can have both high forward transmission efficiency and low reverse transmission efficiency, and the reverse efficiency is flexibly adjustable, the motor assembly using the transmission mechanism has the advantages of stable power output and strong anti-interference ability, and improves the robustness of the motor, and the wire-controlled steering system and vehicle using the transmission mechanism have the advantages of sufficient steering force and soft road feedback.

Description

Technical Field

[0001] The present application relates to the technical field of asymmetric efficiency transmission, and in particular to an asymmetric efficiency transmission mechanism, a motor assembly, a wire-controlled steering system and a vehicle. Background Art

[0002] In the field of mechanical transmission, many scenarios require the transmission mechanism to have different forward transmission efficiencies and reverse transmission efficiencies, or even require that the power can only be transmitted in one direction. Such a transmission mechanism is an asymmetric efficiency transmission mechanism. Worm gear mechanisms, trapezoidal screw mechanisms, planetary roller screw mechanisms, etc. are all typical asymmetric efficiency transmission mechanisms. So far, the existing asymmetric efficiency transmission mechanisms have at least the following technical contradictions in the design and even application stages:

[0003] (1) There is a contradiction between the forward and reverse transmission efficiencies of the mechanism. For example, if the overall forward transmission efficiency of the mechanism is improved, the reverse transmission efficiency of the mechanism will often be improved. On the contrary, if the overall reverse transmission efficiency of the mechanism is reduced, the forward transmission efficiency of the mechanism will often be reduced. If reliable reverse self-locking is required, the forward transmission efficiency may even be lower than 30%, which is unacceptable in some energy-sensitive occasions.

[0004] Taking the rack and pinion electric power steering (P-EPS) and the dual rack and pinion electric power steering (DP-EPS) as examples, the transmission mechanism between the steering actuator motor and the steering wheel can be regarded as an asymmetric efficiency transmission mechanism. The transmission process is roughly as follows: the motor first drives a small gear to rotate through a pair of worm gear structures, and the small gear meshes with the steering gear rack to convert the rotational motion of the gear into the lateral movement of the rack, driving the steering rod to move so that the steering wheel can be turned. Although the reverse transmission efficiency of the mechanism can be reduced by setting the worm gear structure, thereby better filtering the load impact and harmful excitation from the road surface, the worm gear structure with low reverse efficiency often has a large transmission ratio, and the friction and wear between the teeth are severe during meshing, so the forward transmission efficiency of the mechanism is also reduced, which also means that the power distributed by the transmission mechanism on the steering actuator module, such as on the steering gear rack, is further reduced. According to statistics, the maximum rack force that can be distributed to the steering rack of the above two steering gears is only 12kN, while the wire-controlled steering system is generally used for electric vehicles, which are relatively heavy and generally require a rack force of 15kN. Therefore, the weakening of the forward transmission efficiency of the mechanism is unacceptable for the performance design of the above two electric power steering gears.

[0005] (2) There is a contradiction between the transmission efficiency and transmission ratio of the mechanism. For example, when the design goal is to reduce the reverse transmission efficiency of the mechanism, the forward transmission ratio of the mechanism is often increased. In particular, when the transmission mechanism requires better self-locking performance, a very large forward transmission ratio must be adopted. For example, the forward transmission ratio of the self-locking worm gear structure generally needs to exceed 30. The increase in the transmission ratio not only means that the friction and wear generated by the worm gear structure when the teeth are meshed will be further aggravated, thereby reducing the forward transmission efficiency of the mechanism, but also will have a greater impact on a series of parameters related to steering control, such as steering sensitivity, steering angle, road feel feedback, etc., so that the steering system cannot obtain the best steering performance.

[0006] In summary, it is necessary to study the transmission principle and form of the above-mentioned asymmetric efficiency transmission mechanism in order to overcome the technical contradictions between the positive and reverse transmission efficiency designs and the technical contradictions between the transmission efficiency and transmission ratio designs. Summary of the invention

[0007] In view of this, the embodiments of the present specification provide an asymmetric efficiency transmission mechanism, a motor assembly, a wire-controlled steering system and a vehicle. The transmission mechanism has both high forward transmission efficiency and low reverse transmission efficiency, and the reverse efficiency is flexibly adjustable. The motor assembly using the transmission mechanism has the advantages of smooth power output and strong anti-interference ability, which improves the robustness of the motor. At the same time, the wire-controlled steering system and the vehicle using the transmission mechanism have the advantages of sufficient steering force and soft road feedback.

[0008] The embodiments of this specification provide the following technical solutions:

[0009] As a first aspect of the embodiment, an asymmetric efficiency transmission mechanism is provided for transmitting positive torque power from the drive side to the load side, the transmission mechanism having a first transmission path and a second transmission path connected in parallel, the first transmission path being configured to have a high forward transmission efficiency and comprising a first drive side shaft component and a first load side shaft component; the second transmission path being configured to have a low reverse transmission efficiency and comprising a second drive side shaft component and a second load side shaft component; wherein the first drive side shaft component and the second drive side shaft component are transmission-connected by a drive side node structure and the torsional stiffness of the first drive side shaft component is greater than that of the second drive side shaft component, and the first load side shaft component and the second load side shaft component are transmission-connected by a worm gear structure and the second load side shaft serves as a worm gear shaft and the first load side shaft serves as a worm gear shaft.

[0010] As a preferred embodiment, the second drive-side shaft component includes a second drive-side shaft and a second coupling mounted on the second drive-side shaft, and the second drive-side shaft is coupled to the second load-side shaft component through the second coupling.

[0011] As a preferred embodiment, the first drive side shaft component includes a first drive side shaft and a first coupling installed on the first drive side shaft, the first drive side shaft is coupled to the first load side shaft component through the first coupling, and the torsional stiffness of the first coupling is greater than that of the second coupling.

[0012] As a preferred embodiment, the first coupling is a rigid coupling or a flexible coupling, and the second coupling is a flexible coupling. In particular, the flexible coupling is, for example, a rubber coupling or a spring coupling.

[0013] As a preferred embodiment, the first drive-side shaft component and the first load-side shaft component are integrally formed and connected and are coaxially arranged.

[0014] As a preferred embodiment, the second transmission path is arranged in a multi-stage transmission form.

[0015] As a preferred embodiment, the worm gear structure is configured such that the forward transmission efficiency does not exceed 50% and the reverse transmission efficiency does not exceed 10%. In particular, the worm gear structure is a self-locking worm gear structure.

[0016] As a preferred embodiment, the axial restraint rigidity of the second load-side shaft component is greater than the torsional rigidity of the first load-side shaft component.

[0017] As a preferred embodiment, the driving side node structure is a gear transmission structure, such as a bevel gear transmission structure or a cylindrical gear transmission structure.

[0018] As a second aspect of the embodiment, a motor assembly is provided, comprising a drive motor and the above-mentioned asymmetric efficiency transmission mechanism, wherein the first drive-side shaft component is suitable for obtaining power from the motor shaft of the drive motor.

[0019] As a preferred embodiment, the first driving-side shaft component is integrally connected to the motor shaft of the driving motor.

[0020] As a third aspect of the embodiment, there is provided a steer-by-wire system comprising the above-mentioned motor assembly.

[0021] As a fourth aspect of the embodiment, a vehicle is provided, comprising the above-mentioned steer-by-wire system.

[0022] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0023] On the one hand, in the present embodiment, the transmission mechanism has two transmission paths, namely the first transmission path and the second transmission path. When the torque power transmitted from the driving side in the positive direction passes through the driving side node structure, since the torsional stiffness of the first driving side shaft component is greater than that of the second driving side shaft component, according to the constraint of deformation coordination, most of the power will enter the first transmission path with high forward transmission efficiency from the first driving side shaft component with larger torsional stiffness, and only a small part of the power will be diverted from the second driving side shaft component with smaller torsional stiffness to the second transmission path with relatively lower forward transmission efficiency. That is, at this time, the energy consumed on the second transmission path is less, so the total forward transmission efficiency of the mechanism is still high. On the contrary, the power from the load When the torque power transmitted in the reverse direction along the side passes through the worm gear structure, since the axial constraint stiffness of the worm shaft is greater than the torsional stiffness of the mechanism, most of the power enters the second transmission path with lower reverse transmission efficiency from the worm shaft, i.e., the second load-side shaft component, and only a small part of the power enters the first transmission path with relatively higher reverse transmission efficiency from the worm shaft, i.e., the first load-side shaft component. That is, most of the energy will be consumed in the second transmission path at this time, so that the overall reverse transmission efficiency of the mechanism is still low. In summary, the transmission mechanism can have both high forward transmission efficiency and low reverse transmission efficiency, and the forward and reverse transmission efficiencies can be flexibly configured according to the specific forms of the transmission forms on the two transmission paths.

[0024] Secondly, in this embodiment, according to the constraints of deformation coordination, by adjusting the stiffness characteristics of the first drive-side shaft component, the total forward transmission efficiency of the mechanism can be adjusted without almost affecting the total reverse transmission efficiency of the mechanism. By adjusting the stiffness characteristics of the second output shaft on the second transmission path, the total reverse transmission efficiency of the mechanism can be adjusted without almost affecting the forward transmission efficiency of the mechanism, thereby achieving structural decoupling of the forward transmission efficiency and reverse transmission efficiency of the mechanism.

[0025] Thirdly, in this embodiment, the different distribution ratios of torque power in forward and reverse transmission are determined by the mechanical characteristics of the structure and are fully adaptive, without the need for active intervention.

[0026] Fourthly, in this embodiment, according to the constraints of deformation coordination, the influence of adjusting the transmission ratio of the first transmission path on the transmission efficiency of the mechanism can be bridged and offset by adjusting the stiffness characteristics of the first drive side shaft component or the second drive side shaft component, thereby achieving structural decoupling between the transmission ratio and the transmission efficiency of the mechanism, further enhancing the adaptability and flexibility of the transmission mechanism when applied.

[0027] Fifthly, the motor assembly equipped with the above-mentioned asymmetric efficiency transmission mechanism can effectively shield most of the disturbances and excitations from the load side due to its low reverse transmission efficiency. At the same time, due to its high forward transmission efficiency, the power output from the drive motor to the load side is sufficient and stable.

[0028] Sixthly, for the steer-by-wire system and vehicle using the above-mentioned motor assembly, when applied to steering execution, it can output sufficient and stable steering execution power and reduce harmful excitations and disturbances transmitted from the road surface to the steering wheel, thereby obtaining a better driving experience; when applied to steering control, it can output sufficient and stable steering control power and reduce the interference of hand torque on the road feel simulation motor. In short, the application of the above-mentioned asymmetric efficiency transmission mechanism can further improve the steering performance of the vehicle steering system, while obtaining a more comfortable driving experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 It is a schematic diagram of the transmission structure of the first embodiment of the present application;

[0031] Figure 2 It is a schematic diagram of the structure of some components in Example 1 of the present application;

[0032] Figure 3 It is a schematic diagram of the structure of other parts in the first embodiment of the present application;

[0033] Figure 4 It is a schematic diagram of the transmission structure of the second embodiment of the present application;

[0034] Figure 5 It is a schematic diagram of the transmission structure of the third embodiment of the present application;

[0035] Figure 6 It is a transmission structure schematic diagram of the asymmetric efficiency transmission mechanism in Example 3 of the present application.

[0036] Reference numerals:

[0037] In the first embodiment:

[0038] 1. Drive end; 2. Load end; 3. First transmission path; 31. First drive side shaft; 32. First intermediate transmission structure; 33. First load side shaft; 4. Second transmission path; 41. Second drive side shaft; 42. Second intermediate transmission structure; 43. Second load side shaft; 5. Drive side node structure; 51. First bevel gear; 52. Second bevel gear; 6. Worm gear structure; 61. Worm; 62. Worm wheel; 12. Bearing; Q1. First equivalent torsional deformation; Q2. Second equivalent torsional deformation; L1. Equivalent axial displacement;

[0039] In the second embodiment:

[0040] 100, driving motor; 311, first driving side shaft; 321, rigid coupling; 331, first load side shaft; 4211, cylindrical gear set; 51, driving side node structure; 511, planetary gear set; 61, worm gear structure; 7, fastener;

[0041] In the third embodiment:

[0042] 200, steering motor; 201, steering motor controller; 301, asymmetric efficiency transmission mechanism; 401, synchronous belt transmission component; 501, lead screw nut; 502, ball screw; 601, steering shaft;

[0043] 312, first drive side shaft; 322, first coupling; 332, first load side shaft; 412, second drive side shaft; 422, second intermediate transmission structure; 432, second load side shaft; 442, second coupling; 52, drive side node structure; 62, worm gear structure. DETAILED DESCRIPTION

[0044] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0045] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0046] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0047] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0048] The embodiments of this specification propose an asymmetric efficiency transmission mechanism, which aims to solve the problem in the prior art that asymmetric efficiency transmission mechanisms cannot simultaneously have high forward transmission efficiency and low reverse transmission efficiency. The idea of ​​power diversion not only makes the transmission mechanism have the characteristics of high forward transmission efficiency and low reverse transmission efficiency, but also further realizes the structural decoupling between the forward transmission efficiency and the reverse transmission efficiency of the mechanism and the decoupling between the transmission ratio and the transmission efficiency, which greatly increases the scope of application of the transmission mechanism as well as its flexibility and adaptability in application.

[0049] The technical solutions provided by various embodiments of the present application are described below in conjunction with the accompanying drawings.

[0050] Embodiment 1

[0051] like Figure 1 to Figure 3 As shown, an asymmetric efficiency transmission mechanism is used to transmit positive torque power from a driving side to a load side. The transmission mechanism has a first transmission path 3 and a second transmission path 4 connected in parallel. Figure 2 The middle arrow S1 roughly shows the direction of the first transmission path 3 during forward transmission. Figure 3 The middle arrow S2 roughly shows the direction of the second transmission path 4 during forward transmission. The first transmission path 3 is configured to have a high forward transmission efficiency and includes a first drive side shaft component and a first load side shaft component. The second transmission path 4 is configured to have a low reverse transmission efficiency and includes a second drive side shaft component and a second load side shaft component.

[0052] The first drive side shaft component and the second drive side shaft component are connected by a drive side node structure 5 and the torsional stiffness of the first drive side shaft component is greater than that of the second drive side shaft component. Figure 1 As shown, the angular displacement of the output end of the first drive side shaft component relative to its input end during forward transmission under the state of loading the rated transmission load is recorded as the first equivalent torsional deformation Q1, which is used to measure the torsional stiffness k1 of the first drive side shaft component. Under the same state, the angular displacement of the output end of the second drive side shaft component relative to its input end during forward transmission is recorded as the second equivalent torsional deformation Q2, which is used to measure the torsional stiffness k2 of the first drive side shaft component, then k1>k2.

[0053] The first load-side shaft component and the second load-side shaft component are connected by a worm gear structure 6, and the second load-side shaft 43 is used as the worm shaft and the first load-side shaft 33 is used as the worm gear shaft. Figure 3 As shown, the worm 61 is assembled on the second load-side shaft, and the worm wheel 62 is assembled on the first load-side shaft. Having low reverse transmission efficiency or self-locking characteristics is an important known characteristic of the worm gear transmission structure. When the worm wheel and worm are engaged, the worm shaft will be subjected to a large axial force. In order to prevent the worm from axial displacement or deformation, the axial constraint stiffness of the worm shaft must meet the target design value, while the torsional stiffness of the worm wheel shaft does not need to exceed this design value. Therefore, in the worm gear transmission structure, the axial constraint stiffness of the worm shaft should be greater than the torsional stiffness of the worm wheel shaft. Specifically, as shown in the figure, the axial displacement of the worm shaft under the rated transmission load is recorded as the equivalent axial displacement L1, and the displacement of the equivalent axial displacement L1 is used to measure the axial constraint stiffness k of the second load-side shaft, i.e., the worm shaft. s , then k s Greater than the torsional stiffness of the worm gear shaft.

[0054] In this embodiment, the transmission mechanism has two transmission paths, a first transmission path 3 and a second transmission path 4. When the torque power transmitted from the driving side in the positive direction passes through the driving side node structure 5, since the torsional stiffness of the first driving side shaft component is greater than that of the second driving side shaft component, according to the constraint of deformation coordination, most of the power will enter the first transmission path 3 with high forward transmission efficiency from the first driving side shaft component with larger torsional stiffness, and only a small part of the power will be diverted from the second driving side shaft component with smaller torsional stiffness to the second transmission path 4 with relatively lower forward transmission efficiency. That is, at this time, the energy consumed on the second transmission path is less, so the total forward transmission efficiency of the mechanism is still high. On the contrary, from the load side along When the torque power transmitted in reverse passes through the worm gear structure 6, since the axial constraint stiffness of the worm shaft is greater than the torsional stiffness of the mechanism, most of the power enters the second transmission path 4 with lower reverse transmission efficiency from the worm shaft, i.e., the second load-side shaft component, and only a small part of the power enters the first transmission path 3 with relatively higher reverse transmission efficiency from the worm shaft, i.e., the first load-side shaft component. That is, most of the energy will be consumed in the second transmission path 4 at this time, so that the overall reverse transmission efficiency of the mechanism is still low. In summary, the transmission mechanism can have both high forward transmission efficiency and low reverse transmission efficiency, and the forward and reverse transmission efficiencies can be flexibly configured according to the specific forms of the transmission forms on the two transmission paths.

[0055] As one of the development methods, in this embodiment, the second drive side shaft component includes a second drive side shaft 41 and a second coupling installed on the second drive side shaft 41, and the second drive side shaft 41 is coupled to the second load side shaft component through the second coupling. It should be noted that the "coupling" here should be understood in a broad sense, that is, all components that can realize the coupling function of the two transmission shafts should be included, for example, elastic rubber blocks or springs that realize the coupling of the two transmission shafts should also be included in the category of the "coupling", as long as they can provide a certain torsional deformation and under the premise of meeting the transmission requirements, the stiffness characteristics of the first drive side shaft 31 and the second drive side shaft 41 meet the set gap value. In this case, the shaft parts of the first drive side shaft component and the first load side shaft component can be integrally connected and the two are coaxially configured. Since the torsional stiffness of the transmission shaft is much greater than that of the coupling, torsional deformation will only occur in the corresponding coupling part under the above loading state. Therefore, the torsional stiffness of the second drive side shaft component here can also be represented by the torsional stiffness of the second coupling, that is, the torsional stiffness of the second drive side shaft component can be controlled by controlling the torsional stiffness of the second coupling. Obviously, in order to meet the stiffness characteristic requirement that the torsional stiffness of the first drive side shaft component is greater than that of the second drive side shaft component, the second coupling here preferably adopts a flexible coupling. Furthermore, the second coupling can adopt a rubber coupling, a spring coupling or a diaphragm coupling, etc.

[0056] As another development, the first drive side shaft component includes a first drive side shaft 31 and a first coupling mounted on the first drive side shaft 31, the first drive side shaft 31 is coupled to the first load side shaft component through the first coupling, and the torsional rigidity of the first coupling is greater than that of the second coupling, and each transmission shaft in the mechanism is supported by a certain number of bearings 12. Similarly, the first coupling can be a rigid coupling or a flexible coupling, and the second coupling is a flexible coupling, in particular, the flexible coupling is, for example, a rubber coupling or a spring coupling, which is not limited here.

[0057] In this embodiment, the second transmission path is arranged in a multi-stage transmission form. In this embodiment, one of the functions of the second transmission path is to consume energy in the transmission process, especially the energy in the reverse transmission process, to prevent it from entering the drive side. When other conditions have been determined, the increase in the number of transmission stages can increase the attenuation amplitude of the reverse transmission efficiency along the second transmission path, thereby reducing the interference of the reverse transmission on the drive side. Specifically, the second load-side shaft component includes a second load-side shaft 43 and a second intermediate transmission structure 42 installed on the second load-side shaft 43. The second intermediate transmission structure 42 is located between the second coupling and the worm gear structure 6 along the second transmission path 4. The second intermediate transmission structure 42 can be a primary transmission structure such as a cylindrical gear transmission structure, a planetary gear transmission structure, a synchronous belt transmission structure, or a multi-stage transmission structure including a worm gear and an external gear transmission assembly. Similarly, in order to enable the mechanism to obtain a desired transmission ratio, an intermediate transmission structure may also be provided on the first transmission path 3. Specifically, the first load-side shaft component may include a first load-side shaft 33 and a first intermediate transmission structure 32 mounted on the first load-side shaft 33. The first intermediate transmission structure 32 is located between the first coupling and the worm gear structure 6 along the first transmission path. It may be a cylindrical gear transmission structure, a bevel gear transmission structure, etc. with a target transmission ratio. There is no limitation here. Technicians may select and design according to the requirements of specific working conditions.

[0058] In this embodiment, the worm gear structure is configured such that the forward transmission efficiency does not exceed 50% and the reverse transmission efficiency does not exceed 10%. In particular, the worm gear structure is a self-locking worm gear structure. In addition, the axial constraint stiffness of the second load-side shaft component is greater than the torsional stiffness of the first load-side shaft component, so that according to the constraint of deformation coordination, most of the power is diverted from the worm shaft to the second transmission path 4 during reverse transmission, and the energy of reverse transmission is consumed by the second transmission path 4.

[0059] In this embodiment, the driving side node structure 5 is a gear transmission structure, such as a bevel gear transmission structure or a cylindrical gear transmission structure, or other combined transmission structures. Here, the bevel gear transmission structure is taken as an example. The bevel gear transmission structure includes a first bevel gear 51 and a second bevel gear 52 that are meshed and connected to each other, wherein the first bevel gear 51 is assembled on the first driving side shaft 31, and the second bevel gear 52 is assembled on the second driving side shaft 41. The distribution of driving side power is achieved through the cooperation of the first bevel gear 51 and the second bevel gear 52.

[0060] In order to more clearly reveal the physical mechanism of the solution in this embodiment, the various output parameters of the transmission mechanism of this embodiment are further verified in combination with the specific design method of the transmission mechanism.

[0061] like Figure 1 to Figure 3 As shown, assuming that the forward transmission ratio of the first intermediate transmission structure 32 is i1, the forward and reverse transmission mechanical efficiencies are η1 and η'1 respectively, where the transmission ratio i1 is also the transmission ratio of the mechanism. Since the two transmission paths are configured in parallel and share the same drive side shaft and the same load side shaft on the drive side and the load side respectively, the transmission ratios on the two paths are also equal. The forward transmission ratio of the drive side node structure 5 is i2, and the forward and reverse transmission mechanical efficiencies are η2 and η'2 respectively. The forward transmission ratio of the second intermediate transmission structure 42 is i3, and the forward and reverse transmission mechanical efficiencies are η3 and η'3 respectively. The transmission ratio of the worm gear structure 6 is The forward and reverse transmission mechanical efficiencies are η4 and η'4.

[0062] If the pitch circle diameter of the worm wheel 62 is R, when the axial force on the worm causes the worm 61 to produce an overall translation s0 along the axial direction, the worm wheel will rotate through a corresponding angle That is, the axial constraint stiffness of the worm shaft corresponds to an equivalent torsional stiffness k' on the worm wheel shaft. s =R 2 k s . Let k1 and k2, k1 and k' be s Ratio k 12 , k 1s .

[0063] By establishing the deformation coordination equation, it can be calculated that when the transmission is forward, the torque transmitted through the first transmission path 3 and the second transmission path 4 is Overall efficiency of the organization When the reverse transmission is performed, the torque transmitted through the first transmission path 3 and the second transmission path 4 is Overall efficiency of the organization

[0064] It can be seen from the mathematical expression that when the mechanism is transmitting in the forward direction, due to the diversion of the second transmission path 4 with lower efficiency, the overall efficiency of the mechanism will be slightly lower than the efficiency of the first transmission path 3. 12 , k 1s The effect of improving the overall efficiency of the transmission ratios i1 and i2 is far greater than the effect of weakening the overall efficiency due to the low η4. The physical mechanism is that the torsional stiffness of the first transmission path 3 on the driving side is greater than that of the second transmission path 4, that is, the torsional stiffness of the first driving side shaft component is greater than that of the second driving side shaft component. Due to the constraint of deformation coordination, the power transmitted by the path with greater stiffness is also greater. Therefore, most of the power is transmitted through the first transmission path 3 with higher efficiency, and the overall energy loss caused by the inefficient second transmission path 4 is very small, so the mechanism still has a very high total forward transmission efficiency.

[0065] When the mechanism is reversely transmitted, due to the self-locking effect of the worm gear, η'4 is close to or equal to 0, and since the axial constraint stiffness of the worm gear shaft is generally much greater than the torsional stiffness of the transmission system, most or even all of the power is transmitted by the second transmission path 4. At this time, the overall efficiency basically depends on the self-locking performance of the worm gear. When the axial constraint of the worm is reliable and the self-locking of the worm gear is reliable, the system as a whole can achieve self-locking, that is, it has a very low reverse transmission efficiency.

[0066] In addition, in this embodiment, when the transmission ratio i1 is determined, the transmission ratio i2 can be flexibly defined in the design, k1, k2, k s Precise control can be achieved through structural design, material selection, and setting couplings with target stiffness characteristics in the path. The efficiency of the mechanism can be precisely designed by adjusting the parameters. In addition, under the condition that i2 and k1 are determined, changing k2 can adjust the total forward transmission efficiency of the mechanism without basically affecting the total reverse transmission efficiency. Conversely, changing k s The total reverse transmission efficiency of the mechanism can be adjusted without substantially affecting the total forward transmission efficiency, thereby achieving structural decoupling of the forward and reverse transmission efficiencies. The effect of adjusting the transmission ratio of the mechanism on the transmission efficiency of the mechanism can be offset by adjusting the stiffness characteristics of the first drive side shaft component or the second drive side shaft component, thereby achieving structural decoupling between the transmission ratio of the mechanism and the transmission efficiency, further enhancing the flexibility and adaptability of the transmission mechanism in application.

[0067] Furthermore, in this embodiment, the different distribution ratios of torque power in forward and reverse transmission are determined by the mechanical characteristics of the structure and are completely adaptive, without the need for active intervention.

[0068] Embodiment 2

[0069] like Figure 4 As shown, this embodiment provides a motor assembly, including a drive motor 100 and the asymmetric efficiency transmission mechanism described in the first embodiment, wherein the first drive side shaft component is suitable for obtaining power from the motor shaft of the drive motor 100 .

[0070] Specifically, the asymmetric efficiency transmission mechanism is placed as a whole in a casing, and the casing is connected to the outer shell of the drive motor 100 through a fastener 7. The first drive side shaft component includes a first drive side shaft 311 and a rigid coupling 321. The first drive side shaft 311 is integrally connected to the motor shaft of the drive motor 100. The first intermediate transmission mechanism is not set on the first load side shaft 331. The first drive side shaft 311 is rigidly connected to the first load side shaft 331 through the rigid coupling 321, that is, i1=1, η1=η'1=100%, and the drive side node structure 51 includes a bevel gear pair and a planetary gear set 511 meshingly connected to the driving wheel of the bevel gear pair. The driven wheel of the bevel gear pair is installed on the second drive side shaft 311. During forward transmission, the power is transmitted from the bevel gear to the first load side shaft 331. The flow is diverted. Here, the forward and reverse transmission efficiencies of the driving side node structure 51 can reach more than 90%. The second load side shaft component includes a second load side shaft and a second intermediate transmission mechanism 4211 installed on the second load side shaft. The second intermediate transmission mechanism 4211 is a cylindrical gear set transmission structure, one end of which has an input transmission shaft, which is coupled to the second driving side shaft through an elastic coupling. The forward and reverse transmission efficiency of the second intermediate transmission mechanism 4211 is η3=η'3, and η3 is 95% to 99%. The worm gear structure 61 is less efficient because it needs to have reliable self-locking performance. Its forward transmission efficiency η4 does not exceed 50%, and the reverse transmission efficiency η'4 does not exceed 10%. If a self-locking worm gear is used, η'4=0.

[0071] When i2≥1, k 12 Take 2, k 1s Taking 0.3 and substituting it into the above formula, it is calculated that the total forward transmission efficiency of the mechanism is above 80%, and the total reverse transmission efficiency does not exceed 25%.

[0072] In this embodiment, the motor assembly is equipped with the above-mentioned asymmetric efficiency transmission mechanism. Since the reverse transmission efficiency is low, it can effectively shield most of the disturbances and excitations from the load side. At the same time, due to the high forward transmission efficiency, the power output from the drive motor 100 to the load side is sufficient and stable.

[0073] Embodiment 3

[0074] refer to Figures 5 and 6As shown, this embodiment provides a wire-controlled steering system and a vehicle using the wire-controlled steering system, wherein the wire-controlled steering system includes the above-mentioned motor assembly, specifically, the steering system includes a motor assembly and a steering actuator, the motor assembly includes a steering motor 200 and an asymmetric efficiency transmission mechanism 301 connected between the steering motor 200 and the steering actuator, the steering motor 200 is controlled by a steering motor controller 201 for speed and torque, the motor shaft of the steering motor 200 is coupled to a first driving side shaft 312 of the asymmetric efficiency transmission mechanism 301, preferably, the motor shaft of the steering motor 200 The machine shaft is integrally connected to the first drive side shaft 312, and the steering actuator specifically includes a synchronous belt transmission component 401, a ball screw assembly and a steering shaft 601, wherein the driving wheel of the synchronous belt transmission component 401 is coupled to the first load side shaft 332 of the asymmetric efficiency transmission mechanism 301, and the ball screw assembly includes a screw nut 501 rigidly connected to the driven wheel of the synchronous belt transmission component 401 and a ball screw 502 matched with the screw nut 501, one end of the ball screw 502 is rigidly connected to the steering shaft 601, and one end of the steering shaft 601 is connected to the steering wheel through a ball pin and a steering knuckle. During the steering process, the controller controls the steering motor 200 to output the target torque according to the needs of the whole vehicle. The torque power is transmitted from the asymmetric efficiency transmission mechanism 301 to the synchronous belt transmission component 401, driving the driven wheel of the synchronous belt transmission component 401 to rotate, so that the screw nut 501 follows the rotation, driving the ball screw 502 and the steering shaft 601 to move laterally along the shell, thereby controlling the deflection of the steering wheel of the whole vehicle.

[0075] refer to Figure 6 As shown, in the asymmetric efficiency transmission mechanism 301 in this embodiment, the first intermediate transmission mechanism is not arranged on the first load side shaft 332, and the first drive side shaft 312 is coupled with the first load side shaft 332 through the first coupling 322. At this time, the transmission ratio of the first transmission path 3 is 1, and the forward and reverse transmission efficiencies are close to 100%. The second drive side shaft 412 is coupled with the second load side shaft 432 through the second coupling 442, and the second intermediate transmission structure 422 is composed of a pair of cylindrical gears with a transmission ratio less than 1. The transmission ratio of the second transmission path 4 is also 1, but the forward and reverse transmission efficiencies are lower than those of the first transmission path 3. The drive side node structure 52 adopts a bevel gear transmission structure, and the load side node structure adopts a worm gear structure 62.

[0076] In this embodiment, i2 is designed to be 3, k 12 Take 2, k 1s Take 0.3, design the worm gear to be self-locking, design i1 to be 1, and the rest are the same as in Example 2. Substitute the deformation coordination equation to calculate that the total forward transmission efficiency of the mechanism is about 97%, and the reverse transmission efficiency is about 23%.

[0077] In addition, the transmission efficiency of the synchronous belt transmission component is about 98%, the forward and reverse transmission efficiencies of the ball screw are about 95% and 90% respectively, and the transmission efficiency of the steering shaft 601 is about 95%. The overall forward transmission efficiency of the steering system involved in this embodiment is about 85%, and the reverse transmission efficiency is about 20%, which meets the ideal design requirements of high forward transmission efficiency and low reverse transmission efficiency. In actual engineering, various parameters can be designed, adjusted and iterated through theoretical calculations and tests, and finally achieve characteristics suitable for the requirements of the vehicle, meeting the different requirements of different vehicles for the steering system.

[0078] In this embodiment, the steer-by-wire system and vehicle using the above-mentioned motor assembly can not only output sufficient and stable steering execution power, but also reduce harmful excitations and disturbances transmitted back to the system by the road surface, thereby allowing the driver to have a more comfortable driving experience.

[0079] It should be noted that the motor assembly in the above embodiment can be applied not only to steering execution, but also to steering control. When applied to steering control, the motor in the motor assembly is a road feel simulation motor, and the output shaft of the motor assembly, that is, the first load-side shaft, is coupled to the steering wheel control mechanism on the load side. Due to the high forward transmission efficiency, the road feel simulation motor can not only output sufficient and stable steering control power to the steering wheel control mechanism, but also reduce the interference of hand torque on the road feel simulation motor. In short, the application of the above-mentioned asymmetric efficiency transmission mechanism can further improve the steering performance of the vehicle steering system, while allowing the driver to have a more comfortable driving experience.

[0080] In this specification, the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiments described later, the description is relatively simple, and the relevant parts can be referred to the partial description of the previous embodiments.

[0081] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. An asymmetric efficiency transmission mechanism for transmitting positive torque power from a drive side to a load side, the transmission mechanism having a first transmission path and a second transmission path connected in parallel, characterized in that: The first transmission path is configured to have a high forward transmission efficiency and includes a first drive-side shaft component and a first load-side shaft component; The second transmission path is configured to have a low reverse transmission efficiency and includes a second drive-side shaft component and a second load-side shaft component; The first drive side shaft component and the second drive side shaft component are connected by a drive side node structure and the torsional stiffness of the first drive side shaft component is greater than that of the second drive side shaft component. The first load side shaft component and the second load side shaft component are connected by a worm gear structure and the second load side shaft serves as the worm shaft and the first load side shaft serves as the worm gear shaft.

2. The asymmetric efficiency transmission mechanism according to claim 1, characterized in that: The second drive-side shaft component includes a second drive-side shaft and a second coupling mounted on the second drive-side shaft, and the second drive-side shaft is coupled to the second load-side shaft component through the second coupling.

3. The asymmetric efficiency transmission mechanism according to claim 2, characterized in that: The first drive side shaft component includes a first drive side shaft and a first coupling installed on the first drive side shaft, the first drive side shaft is coupled to the first load side shaft component through the first coupling, and the torsional stiffness of the first coupling is greater than that of the second coupling; the first coupling adopts a rigid coupling or a flexible coupling, and the second coupling adopts a flexible coupling.

4. The asymmetric efficiency transmission mechanism according to claim 1 or 2, characterized in that: The first drive-side shaft component and the first load-side shaft component are integrally formed and connected and are coaxially arranged.

5. The asymmetric efficiency transmission mechanism according to claim 1, characterized in that: The second transmission path is arranged in a multi-stage transmission form; the worm gear structure is constructed so that the forward transmission efficiency does not exceed 50% and the reverse transmission efficiency does not exceed 10%.

6. The asymmetric efficiency transmission mechanism according to claim 1, characterized in that: The axial constraint stiffness of the second load-side shaft component is greater than the torsional stiffness of the first load-side shaft component; and the drive-side node structure is a gear transmission structure.

7. The motor assembly is characterized in that: It comprises a drive motor and the asymmetric efficiency transmission mechanism according to any one of claims 1 to 7, wherein the first drive-side shaft component is suitable for obtaining power from the motor shaft of the drive motor.

8. The motor assembly according to claim 7, characterized in that: The first driving side shaft component is integrally connected to the motor shaft of the driving motor.

9. A steer-by-wire system, characterized in that: Comprising the motor assembly as claimed in claim 7 or 8.

10. A vehicle, characterized in that Comprising the steer-by-wire system as claimed in claim 9.

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