Commercial electric vehicle power steering system with toroidal worm drive

Abstract

A commercial electric vehicle power steering system (100) includes an input shaft (110), an electric motor (120), a planetary gear set (130), a transmission coupling (140), and an output shaft (150). A first one of a sun gear (132), a carrier (136), and a ring gear (138) of the planetary gear set (130) is connected to and rotatable with a rotor (122) of the electric motor (120), and a second one of the sun gear (132), the carrier (136), and the ring gear (138) of the planetary gear set (130) is connected to and rotatable with a first gear (142) of the transmission coupling (140). A second gear (144) of the transmission coupling (140) is connected to and rotatable with the input shaft (110). A toroidal worm drive (160) is arranged between the input shaft (110) and the output shaft (150). The toroidal worm drive (160) couples the input shaft (110) to the output shaft (150) such that the output shaft (150) is rotatable with the input shaft (110) via the toroidal worm drive (160).

Description

TECHNICAL FIELD

[0001] The present subject matter relates generally to power steering systems for commercial vehicles. BACKGROUND

[0002] Conventional commercial vehicles typically include a hydraulic power steering unit. Known hydraulic power steering systems include a hydraulic piston actuated by pressurized hydraulic fluid from a pump. Both the steering wheel and the hydraulic piston are coupled to a steering linkage, and the pressurized hydraulic fluid from the pump selectively extends and retracts the hydraulic piston to supplement the torque applied to the steering linkage by a driver turning the steering wheel.

[0003] While known hydraulic power steering systems work well in conventional commercial vehicles, utilizing hydraulic power steering in electric and / or hybrid commercial vehicles presents challenges. Commercial electric vehicle power steering systems would be useful. SUMMARY

[0004] Aspects and advantages of the application will be set forth in part in the following description, or can be obvious from the description, or can be learned through practice of the application.

[0005] The present subject matter relates generally to electric power steering systems for commercial vehicles. The electric power steering systems include a toroidal worm drive or double enveloping gear set that can advantageously assist in proving that electric motors have suitable mechanical advantage for power steering of heavy commercial vehicles. The toroidal worm drive can provide such mechanical advantage in a compact package. Thus, the present subject matter can electrically power steer heavy commercial vehicles in a safe, robust, and / or cost-effective manner.

[0006] In an example embodiment, a commercial electric vehicle power steering system includes an input shaft and an electric motor. A planetary gear set includes a sun gear, a plurality of planet gears, a planet carrier, and a ring gear. A first one of the sun gear, the planet carrier, and the ring gear of the planetary gear set is connected to and rotatable with a rotor of the electric motor. A transmission coupling includes a first gear and a second gear. A second one of the sun gear, the planet carrier, and the ring gear of the planetary gear set is connected to and rotatable with the first gear of the transmission coupling. The second gear of the transmission coupling is connected to and rotatable with the input shaft. The example commercial electric vehicle power steering system also includes an output shaft. A toroidal worm drive is disposed between the input shaft and the output shaft. The toroidal worm drive couples the input shaft to the output shaft such that the output shaft is rotatable with the input shaft through the toroidal worm drive.

[0007] In a first example aspect, an input shaft can extend between a first end portion and a second end portion. The input shaft can form a hand drive interface at the first end portion of the input shaft, and a toroidal worm of a toroidal drive can be positioned proximate the second end portion of the input shaft.

[0008] In a second example aspect, a sun gear of a planetary gear set can be connected to and rotatable with a rotor of an electric motor. A carrier of the planetary gear set can be connected to and rotatable with a first gear of a drive coupling.

[0009] In a third example aspect, the drive coupling can further include a belt or chain coupling the first gear of the drive coupling to a second gear of the drive coupling. As an alternative to a belt or chain, the drive coupling can further include at least one additional gear meshing with the first and second gears of the drive coupling.

[0010] In a fourth example aspect, a rotational axis of the output shaft can be perpendicular to a rotational axis of the input shaft. A rotational axis of the rotor of the electric motor can be parallel to the rotational axis of the input shaft.

[0011] In a fifth example aspect, a toroidal worm drive can include a toroidal worm meshing with a toroidal gear. The toroidal worm can be positioned on an input shaft, and the toroidal gear can be positioned on an output shaft. The toroidal gear can include a plurality of tooth portions distributed along an arcuate curve of not less than 120 degrees and not more than 200 degrees. A pair of bearings can support the input shaft, and the toroidal worm can be positioned on the input shaft between the pair of bearings. Each bearing of the pair of bearings can be a tapered roller bearing.

[0012] In a sixth example aspect, a commercial vehicle can include an example commercial electric vehicle power steering system. The commercial vehicle can further include a Pitman Arm connected to an output shaft, a knuckle with a steering arm, and a tie rod extending between and connected to the steering arm of the knuckle and the Pitman Arm. The electric motor of the example commercial electric vehicle power steering system can be operable to turn the knuckle.

[0013] In certain embodiments, each of the example aspects listed above can be combined with one or more of the other example aspects listed above. For example, in some embodiments, all six of the example aspects listed above can be combined with each other. As another example, any combination of two, three, four, or five of the six example aspects listed above can be combined in other embodiments. Thus, in some example embodiments, the example aspects listed above can be used in conjunction with each other. Alternatively, in other example embodiments, the example aspects listed above can be implemented individually. Thus, it should be understood that a variety of example embodiments can be implemented utilizing the example aspects listed above.

[0014] These and other features, aspects, and advantages of the present application will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and serve to explain the principles of the application. BRIEF DESCRIPTION OF DRAWINGS

[0015] A complete and enabling disclosure of the application, including the best mode thereof, to one of ordinary skill in the art, is set forth in the specification taken in conjunction with the accompanying drawings.

[0016] Figure 1 is a perspective view of an exemplary commercial electric vehicle power steering system according to example embodiments of the present subject matter installed within a commercial vehicle, shown schematically;

[0017] Figure 2 is Figure 1 a schematic view of an exemplary commercial electric vehicle power steering system of

[0018] Figure 3 is Figure 1 a perspective view of an exemplary commercial electric vehicle power steering system of

[0019] Figure 4 is a side elevational view of an exemplary commercial electric vehicle power steering system of Figure 1 installed on a frame of a commercial vehicle;

[0020] Figure 5 is Figure 1 a partial elevational view of certain components of an exemplary commercial electric vehicle power steering system of

[0021] Figure 6 is a partial elevational view of certain components of a commercial electric vehicle power steering system according to another exemplary embodiment of the present subject matter;

[0022] Figure 7 is Figure 1Another partial elevation view of a specific component of an exemplary commercial electric vehicle power steering system;

[0023] Figure 8 yes Figure 1 A partial perspective view of a toroidal worm gear transmission mechanism in an exemplary power steering system for a commercial electric vehicle; and

[0024] Figure 9 and Figure 10 These are views of a toroidal worm gear drive mechanism of a power steering system for a commercial electric vehicle according to another exemplary embodiment of this subject matter. Detailed Implementation

[0025] Reference will now be made in detail to embodiments of the invention, one or more of which are illustrated in the accompanying drawings. Each embodiment is provided in a manner that explains the invention and not limits it. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to the invention without departing from the scope or spirit of the invention. For example, features shown or described as part of one embodiment may be used with another embodiment to produce yet another embodiment. Therefore, the invention is intended to cover such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0026] As used herein, similar to the use of the term "comprising," the terms "comprising" and "including" are intended to be open-ended. Similarly, the term "or" is generally intended to be open-ended, i.e., "A or B" is intended to mean "A or B or both." Approximate language used throughout the specification and claims is used to modify any quantitative expression that may be varied but does not result in a change to the essential function associated with it. Therefore, values ​​modified by one or more terms such as "about," "approximately," and "substantially" are not limited to the specified precise value. In at least some cases, approximate language may correspond to the precision of the instrument used to measure the value. For example, approximate language may refer to a margin of ten percent (10%).

[0027] Exemplary embodiments of this disclosure relate to an electric power steering system for heavy-duty commercial vehicles. The electric power steering system may include a toroidal worm gear drive or a double-envelope worm gear set. The toroidal worm gear drive advantageously provides mechanical advantages between the electric motor and / or the vehicle handwheel and the output shaft. Furthermore, the electric power steering system provides a mechanically robust, safe, and cost-effective power steering system for heavy-duty commercial vehicles.

[0028] Figure 1 This is a perspective view of a power steering system 100 for a commercial electric vehicle, installed within a commercial vehicle 10 according to an exemplary embodiment of the subject matter, and is shown schematically. Figures 2 to 10Further shown are various views and components of the commercial electric vehicle power steering system 100. As discussed in greater detail below, the commercial electric vehicle power steering system 100 includes components for providing a mechanical advantage for the electric motor, such as allowing the electric motor to supplement the torque applied to the steering linkage by the driver turning the steering wheel.

[0029] The commercial electric vehicle power steering system 100 can be installed within the commercial vehicle 10, such as on the frame 12 of the commercial vehicle 10 and / or below the cab 14 of the commercial vehicle 10. Accordingly, the commercial electric vehicle power steering system 100 is described in greater detail below in the context of the commercial vehicle 10, which is generally referred to as a "conventional" type truck. However, it should be understood that the commercial vehicle 10 is provided by way of example only, and that the commercial electric vehicle power steering system 100 can be used in any suitable commercial vehicle, including "conventional cab" type trucks and "cab over engine" type trucks. In general, the commercial electric vehicle power steering system 100 can be used in or with commercial vehicles having a capacity greater than 26,000 pounds (26,000 lbs), greater than 7.5 tons (7.5 t), or other heavy duty trucks.

[0030] Referring to Figures 1 to 4 The commercial electric vehicle power steering system 100 includes an input shaft 110, an electric motor 120, a planetary gear set 130, a transmission coupling 140, an output shaft 150, and a toroidal worm drive 160. The planetary gear set 130, the transmission coupling 140, and the toroidal worm drive 160 can be disposed within a housing 102 of the commercial electric vehicle power steering system 100, such as can be installed on the frame 12 of the commercial vehicle 10. The planetary gear set 130, the transmission coupling 140, and the toroidal worm drive 160 can cooperate and be arranged to provide a mechanical advantage for the electric motor 120, such as allowing the electric motor 120 to supplement the drive torque applied at the input shaft 110 to facilitate turning of the wheels 20 of the commercial vehicle 10, as described in greater detail below.

[0031] The input shaft 110 can be coupled to the steering wheel 40 of the commercial vehicle 10. For example, the steering wheel 40 can be coupled to the input shaft 110 through a steering column 42 of the commercial vehicle 10 that extends between and connects the steering wheel 40 to the input shaft 110, and a driver of the commercial vehicle 10 can turn the steering wheel 40 through the steering column 42 to rotate the input shaft 110, which transmits rotation of the steering wheel 40 to the input shaft 110. In the commercial electric vehicle power steering system 100, the input shaft 110 is coupled to the output shaft 150 such that rotation of the input shaft 110 is transmitted to the output shaft 150. The output shaft 150 is coupled to the steering linkage 30 such that rotation of the output shaft 150 turns the wheels 20 of the commercial vehicle 10. Thus, rotation of the steering wheel 40 by the driver of the commercial vehicle 10 can turn the wheels 20.

[0032] As described above, the commercial electric vehicle power steering system 100 includes features for supplementing the torque applied to the input shaft 110 by the driver turning the steering wheel 20, for example, to make it easier for the driver to steer the commercial vehicle 10. In particular, the electric motor 120 is operable to drive rotation of the input shaft 110, for example, to supplement the torque applied to the input shaft 110 by the driver turning the steering wheel 20. The electric motor 120 can be coupled to the input shaft 110 via the planetary gear set 130 and the transmission coupling 140. Thus, for example, rotation of the electric motor 120 can drive rotation of the input shaft 110 via the planetary gear set 130 and the transmission coupling 140.

[0033] The planetary gear set 130 can be disposed in the power flow between the electric motor 120 and the transmission coupling 140. Thus, for example, the planetary gear set 130 can be configured to transmit rotation of the electric motor 120 to the transmission coupling 140. The planetary gear set 130 can include a sun gear 132, a plurality of planet gears 134, a planet carrier 136, and a ring gear 138. Figure 2 and Figure 7 The planet gears 134 mesh with both the sun gear and the ring gear 138. Thus, for example, within the planetary gear set 130, the planet gears 134 can be positioned between the sun gear 132 and the ring gear 138. It should be appreciated that while the planetary gear set 130 has one set of planet gears 134 and thus is a negative planetary gear set or negative planetary gear set in the illustrated example embodiment, in alternative example embodiments the planetary gear set 130 can include an additional set of planet gears and thus be a positive planetary gear set or positive planetary gear set.

[0034] One of the sun gear 132, the planet carrier 136, and the ring gear 138 of the planetary gear set 130 can be connected to the rotor 122 of the electric motor 120. Figure 2) and is rotatable therewith. Thus, for example, during operation of electric motor 120, one of sun gear 132, carrier 136, and ring gear 138 of planetary gear set 130 can correspond to an input of planetary gear set 130 when windings within electric motor 120 drive rotor 122 to rotate. Further, one of sun gear 132, carrier 134, and ring gear 138 of planetary gear set 130 can rotate when windings within electric motor 120 drive rotor 122 to rotate. In certain example embodiments, sun gear 132 is connected to and rotatable with rotor 122. For example, sun gear 132 can be integrally formed with rotor 122, e.g., such that a toothed portion of sun gear 132 is formed on rotor 122. For example, an end of rotor 122 can be milled, lathed, hobbed, shaped, or otherwise suitably machined to form sun gear 132 on rotor 122. Alternatively, sun gear 132 can be separately formed and subsequently connected to rotor 122, e.g., directly to rotor 122 or with one or more intervening elements, such as a shaft.

[0035] Drive coupling 140 can be disposed in a power flow between planetary gear set 130 and input shaft 110. Thus, for example, drive coupling 140 can be configured to transmit rotation of elements of planetary gear set 130 to input shaft 110, e.g., and thus transmit rotation of electric motor 120 from planetary gear set 130 to input shaft 110. Drive coupling 140 can include first gear 142, second gear 144, and intermediate element 146 for coupling first gear 142 and second gear 144 Figure 5 and Figure 6 ). In Figure 5 the example embodiment shown, intermediate element 146 is configured as a belt that extends between and connects first gear 142 and second gear 144, thereby transmitting rotation of first gear 142 to second gear 144 via the belt. In alternative example embodiments, the belt can be configured as a chain. Figure 6 In the example embodiment shown, intermediate element 146 is configured as a third gear that meshes with first gear 142 and second gear 144, e.g., to form a gear train, thereby transmitting rotation of first gear 142 to second gear 144 via the third gear. In alternative example embodiments, intermediate element 146 can include one or more additional gears that, in combination with the third gear, form a gear train between first gear 142 and second gear 144. As can be seen from the foregoing, drive coupling 140 can be, for example, a traction drive or a gear train configured to transmit rotation of electric motor 120 from planetary gear set 130 to input shaft 110.

[0036] Another one of the sun gear 132, the carrier 136, and the ring gear 138 of the planetary gear set 130 (e.g., different from the one that is connected to and rotatable with the rotor 122) can be connected to and rotatable with the first gear 142 of the drive coupling 140. Thus, for example, the other one of the sun gear 132, the carrier 136, and the ring gear 138 of the planetary gear set 130 can correspond to an output of the planetary gear set 130 during operation of the electric motor 120, and the first gear 142 can correspond to an input to the drive coupling 140 during operation of the electric motor 120. Moreover, the other one of the sun gear 132, the carrier 136, and the ring gear 138 of the planetary gear set 130 that is connected to the first gear 142 can rotate when the windings within the electric motor 120 drive the rotor 122 to rotate. In certain example embodiments, the carrier 136 is connected to and rotatable with the first gear 142. For example, the carrier 136 can be connected to the first gear 142, such as directly or via a suitable shaft or other intermediate component.

[0037] The second gear 144 of the drive coupling 140 can be connected to and rotatable with the input shaft 110. Thus, for example, the second gear 144 can correspond to an output of the drive coupling 140 during operation of the electric motor 120. In certain example embodiments, the second gear 144 can be welded, fastened, or otherwise secured to the input shaft 110.

[0038] As described above, the electric motor 120 can be coupled to the input shaft 110 via the planetary gear set 130 and the transmission coupling 140, for example, such that rotation of the electric motor 120 can drive rotation of the input shaft 110 via the planetary gear set 130 and the transmission coupling 140. For example, the electric motor 120 can be operated such that the rotor 120 rotates, and a first one of the components of the planetary gear set 130 (e.g., the sun gear 132) can rotate during operation of the electric motor 120. Rotation of the first one of the components of the planetary gear set 130 (e.g., the sun gear 132) can drive rotation of a second one of the components of the planetary gear set 130 (e.g., the carrier 136). As the second one of the components of the planetary gear set 130 (e.g., the carrier 136) is coupled to the first gear 142 of the transmission coupling 140, the planetary gear set 130 can transmit rotation of the electric motor 120 to the transmission coupling 140, such that the first gear 142 rotates during operation of the electric motor 120. The intermediate element 146, in turn, can transmit rotation of the first gear 142 to the second gear 144 within the transmission coupling 140, and the input shaft 110 can rotate as a result of the connection of the second gear 144 to the input shaft 110. Thus, during operation of the electric motor 120, the input shaft 110 can rotate, for example, with mechanical advantage provided by the planetary gear set 130 and the transmission coupling 140 for the electric motor 120.

[0039] As described in greater detail below, the commercial electric vehicle power steering system 100 also includes features for coupling the input shaft 110 to the output shaft 150, for example, such that rotation of the input shaft 110 drives rotation of the output shaft 150. In particular, a toroidal worm drive 160 can be disposed between the input shaft 110 and the output shaft 150. The toroidal worm drive 160 couples the input shaft 110 to the output shaft 150 such that the output shaft 150 is able to rotate with the input shaft 110 through the toroidal worm drive 160. In particular, when the driver rotates the steering wheel 40 and / or when the electric motor 120 is operated to rotate the input shaft 110, the toroidal worm drive 160 can transmit rotation of the input shaft 110 to the output shaft 150.

[0040] Hoop worm gear 162 can correspond to an input of hoop worm gear mechanism 160 during rotation of input shaft 110, for example when driver rotates steering wheel 40 and / or when electric motor 120 is operating. Hoop worm gear 162 can be positioned on input shaft 110. For example, hoop worm gear 162 can be integrally formed with input shaft 110. In particular, hoop worm gear 162 can be suitably machined, milled, ground, rolled, shaped, or otherwise machined, to form hoop worm gear 162 on input shaft 110. As another example, hoop worm gear 162 can be separately formed and then connected to input shaft 110, for example with or without the aid of one or more centering elements (e.g., shafts). In certain example embodiments, input shaft 110 can extend between a first end portion 112 and a second end portion 114. Input shaft 110 can form a manual drive interface 116, for example at first end portion 112 of input shaft 110. Steering column 42 can be connected to input shaft 110 at manual drive interface 116, for example by engaging splines on manual drive interface 116. Hoop worm gear 162 can be positioned near second end portion 114 of input shaft 100. Second gear 144 can be positioned on input shaft between manual drive interface 116 and hoop worm gear 162.

[0041] Hoop worm gear 164 can be positioned on output shaft 150. Moreover, hoop worm gear 164 can correspond to an output of hoop worm gear mechanism 160 during rotation of input shaft 110, for example when driver rotates steering wheel 40 and / or when electric motor 120 is operating. In certain example embodiments, hoop worm gear 164 can be welded, fastened, or otherwise secured to output shaft 150.

[0042] Referring to Figure 8 Hoop worm gear 164 can include a plurality of tooth portions 166, and tooth portions 166 of hoop worm gear 164 can be distributed along an arcuate curve that is no less than 120 degrees (120°) and no more than 200 degrees (200°). Thus, tooth portions 166 of hoop worm gear 164 can be distributed arcuately, and the remaining portions of hoop worm gear 164 can not include tooth portions that mesh with hoop worm gear 162. In such example embodiments, hoop worm gear 164 can be a sector gear, and can be lighter than an alternative circular hoop worm gear 164 having tooth portions distributed in a circular fashion (e.g., as shown in Figure 9 and Figure 10

[0043] ​The toroidal worm 162 can also include one or more teeth 168. The teeth 168 of the toroidal worm 162 can increase in diameter from a middle section 169 of the toroidal worm 162 to the two ends of the toroidal worm 162. The teeth 166 of the toroidal worm gear 164 can be necked down, for example, to define a recess at a distal end of the teeth 166 of the toroidal worm gear 164 that is complementary in shape to the teeth 168 of the toroidal worm 162. Thus, the toroidal worm drive 160 can also be referred to as a double envelope worm drive.

[0044] The commercial electric vehicle power steering system 100 can also include a pair of bearings 170 that support the input shaft 110. For example, the bearings 170 can be tapered roller bearings that support radial and / or axial loads from the input shaft 110 at the housing 102. The toroidal worm 162 can be positioned on the input shaft 110 between the bearings 170.

[0045] As described above, the electric motor 120 can be coupled to the input shaft 110 via the planetary gear set 130 and the transmission coupling 140, for example, such that rotation of the electric motor 120 can drive rotation of the input shaft 110 via the planetary gear set 130 and the transmission coupling 140. In addition, the toroidal worm drive 160 couples the input shaft 110 to the output shaft 150, such that the output shaft 150 is able to rotate with the input shaft 110 via the toroidal worm drive 160. Thus, for example, when the driver rotates the steering wheel 40 and / or when the electric motor 120 operates to rotate the input shaft 110, the toroidal worm drive 160 can transmit rotation of the input shaft 110 to the output shaft 150. In particular, when the input shaft 110 rotates, the toroidal worm 162 can rotate, and rotation of the toroidal worm 162 can drive rotation of the toroidal worm gear 164 and the output shaft 150. Thus, the output shaft 150 can rotate during operation of the electric motor 120. The electric motor 120 can be reversible in order to drive rotation of the output shaft 150 in positive and negative directions (e.g., according to the right-hand rule).

[0046] To control operation of electric motor 120, commercial electric vehicle power steering system 100 can include a controller 180 and / or power steering sensors 182. Controller 180 can include a memory and a microprocessor, such as a general purpose microprocessor or a special purpose microprocessor capable of operating to execute program instructions or microcontrol code associated with operation of commercial electric vehicle power steering system 100. The memory can represent random access memory (e.g., DRAM) or read only memory (e.g., ROM or FLASH). In one embodiment, the processor executes program instructions stored in the memory. The memory can be a separate component from the processor, or can be included on board within the processor. Alternatively, controller 180 can be constructed without the use of a microprocessor, such as using a combination of discrete analog and / or digital logic circuits (e.g., switches, amplifiers, integrators, comparators, flip-flops, AND gates, etc.) to perform control functions, rather than relying on software. Electric motor 120 and power steering sensors 182 can communicate with controller 180 via one or more signal lines or a shared communication bus. Controller 180 can also communicate with other systems within commercial vehicle 10 via a controller area network (CAN) bus.

[0047] Power steering sensors 182 can be configured to detect steering torque and / or angle of input shaft 110. In response to input from power steering sensors 182, controller 180 can operate electric motor 120 to drive rotation of output shaft 150. Further, power steering sensors 182 can detect turning of steering wheel 40 by a driver of commercial vehicle 10, and controller 180 can activate electric motor 120 to supplement driver torque applied at input shaft 110 to facilitate turning of wheels 20 of commercial vehicle 10. Further, power steering sensors 182 can detect a direction and extent to which a driver turns steering wheel 40, and controller 180 can operate electric motor 120 to drive rotor 122 in a particular direction for a certain amount of rotation, both of which supplement the detected direction and extent from power steering sensors 182.

[0048] Reference is made to Figure 1 and Figure 4The output shaft 150 can be coupled to a steering linkage 30 of the commercial vehicle 10. For example, the steering linkage 30 can include a Pitman arm 32, steering knuckles 34, tie rods 36, Ackermann arms 37, and tie bars 38. The Pitman arm 32 can be connected to the output shaft 150. The tie rods 36 can extend between and connect to the Pitman arm 32 and steering arms 35 of the steering knuckles 34. For example, a proximal end of the Pitman arm 32 can be mounted to the output shaft 150, and the tie rods 36 can be connected to the Pitman arm 32 at a distal end of the Pitman arm 32. The tie bars 38 can extend between and connect the Ackermann arms 37 of the two steering knuckles 34 to couple the steering knuckles 34 together. The electric motor 120 is operable to rotate the steering knuckles 34, and thereby the wheels 20 of the commercial vehicle 10. For example, by rotating the output shaft 150, the electric motor 120 can pivot the Pitman arm 32, and thereby rotate the steering knuckles 34. Thus, the electric motor 120 is operable to supplement the driver torque applied at the input shaft 110 to facilitate rotation of the wheels 20 of the commercial vehicle 10.

[0049] Referring to Figure 3 In certain example embodiments, the rotational axis RO of the output shaft 150 can be perpendicular to the rotational axis R1 of the input shaft 110. As used herein, the term "perpendicular" means about 90 degrees (90°), such as within 3 degrees (3°) of that angle. The rotational axis RR of the rotor 122 can be parallel to the rotational axis R1 of the input shaft 110. As used herein, the term "parallel" means defining no more than three degrees (3°) between the two axes. Such an orientation can facilitate a compact arrangement of the commercial electric vehicle power steering system 100.

[0050] As can be seen from the foregoing, the commercial electric vehicle power steering system 100 includes components (e.g., the planetary gear set 130, the transmission coupling 140, and the toroidal worm drive 160) for mechanically reducing between the electric motor 120 and / or the steering wheel 40 and the output shaft 150, for example, to convert the low torque and high speed of the electric motor 120 into a useful higher torque and lower speed to effectively steer a heavy commercial vehicle. As an example, the planetary gear set 130, the transmission coupling 140, and the toroidal worm drive 160 can collectively provide a mechanical advantage of approximately 355: 1 to the electric motor 120 to rotate the output shaft 150, for example, the mechanical advantage can be no less than 300: 1 and no greater than 350: 1. It should be appreciated that the mechanical advantage between the electric motor 120 and the output shaft 150 can be selected based on the characteristics (e.g., torque, speed, and acceleration, etc.) of the electric motor 120. Thus, for example, when the torque output of the electric motor 120 is relatively high and has sufficient speed and acceleration, the commercial electric vehicle power steering system 100 can be configured to provide a relatively low mechanical advantage between the electric motor 120 and the output shaft 160 through the planetary gear set 130, the transmission coupling 140, and the toroidal worm drive 160. Conversely, for example, when the torque output of the electric motor 120 is relatively low and has sufficient speed and acceleration, the commercial electric vehicle power steering system 100 can be configured to provide a relatively high mechanical advantage between the electric motor 120 and the output shaft 160 through the planetary gear set 130, the transmission coupling 140, and the toroidal worm drive 160.

[0051] The commercial electric vehicle power steering system 100 can provide a mechanically robust, safe, and cost-effective electric power steering system for heavy commercial vehicles. Moreover, the commercial electric vehicle power steering system 100 can advantageously: (1) electrify the power steering of a heavy commercial vehicle; (2) provide the required mechanical advantage for the electric motor that steers the heavy commercial vehicle; (3) provide a compact power steering system; (4) provide a robust and safe electric power steering system for heavy commercial vehicles; and / or (5) provide a cost-effective electric power steering system for heavy duty commercial vehicles.

[0052] This written description uses examples to disclose the application, including the best mode, and also to enable any person skilled in the art to practice the application, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the application is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

[0053] List of reference signs

[0054] 10 commercial vehicle

[0055] 12 frame

[0056] 14 cab

[0057] 20 wheel

[0058] 30 steering linkage

[0059] 32 pitman arm

[0060] 34 knuckle

[0061] 36 drag link

[0062] 37 ackerman arm

[0063] 38 tie rod

[0064] 40 steering wheel

[0065] 42 steering column

[0066] 100 commercial electric vehicle power steering system

[0067] 102 housing

[0068] 110 input shaft

[0069] 112 first end portion

[0070] 114 second end portion

[0071] 116 manual drive interface

[0072] 120 electric motor

[0073] 122 rotor

[0074] 130 planetary gear set

[0075] 132 sun gear

[0076] 134 planet gears

[0077] 136 planet carrier

[0078] 138 ring gear

[0079] 140 drive coupling

[0080] 142 first gear

[0081] 144 second gear

[0082] 146 intermediate element

[0083] 150 output shaft

[0084] 160 toroidal worm drive

[0085] 162 toroidal worm

[0086] 164 toroidal worm wheel

[0087] 166 tooth portion

[0088] 168 tooth portion

[0089] 169 intermediate section

[0090] 170 bearing

[0091] 180 controller

[0092] 182 power steering sensor

[0093] RO axis of rotation

[0094] RI axis of rotation

[0095] RR axis of rotation

Claims

1. Power steering system for commercial electric vehicles, including: case; An input shaft, which is rotatably mounted within the housing; An electric motor, which is mounted to the housing; A planetary gear set, which is disposed within the housing and includes a sun gear, a plurality of planet gears, a planet carrier, and a ring gear, wherein the first of the sun gear, planet carrier, and ring gear of the planetary gear set is connected to the rotor of the electric motor and is capable of rotating together with the rotor of the electric motor; A transmission coupling unit is disposed within the housing and includes a first gear and a second gear. The second of the sun gear, planet carrier, and ring gear of the planetary gear set is connected to the first gear of the transmission coupling unit and is capable of rotating with the first gear of the transmission coupling unit. The second gear of the transmission coupling unit is connected to the input shaft and is capable of rotating with the input shaft. The transmission coupling unit also includes a belt or chain that couples the first gear of the transmission coupling unit to the second gear of the transmission coupling unit, or it may also include at least one additional gear that meshes with the first gear and the second gear of the transmission coupling unit. An output shaft, which is rotatably mounted within the housing; A toroidal worm gear transmission mechanism is disposed within the housing and arranged between the input shaft and the output shaft. The toroidal worm gear transmission mechanism couples the input shaft to the output shaft, enabling the output shaft to rotate together with the input shaft via the toroidal worm gear transmission mechanism. A Pittman arm, which is connected to the output shaft; Steering knuckle, the steering knuckle having a steering arm; as well as A tie rod that extends between and connects to the steering arm and Pittmann arm of the steering knuckle. The input shaft extends between a first end portion and a second end portion, with a manual drive interface formed at the first end portion, and the toroidal worm gear of the toroidal transmission is positioned near the second end portion of the input shaft. The input shaft can be connected to the steering column at a manual drive interface, allowing the input shaft to rotate via the steering column. The electric motor of the power steering system in the commercial electric vehicle is capable of operation, causing the steering knuckle to rotate.

2. The power steering system for commercial electric vehicles according to claim 1, wherein, The sun gear of the planetary gear set is connected to the rotor of the electric motor and is able to rotate together with the rotor of the electric motor.

3. The power steering system for commercial electric vehicles according to claim 2, wherein, The planet carrier of the planetary gear set is connected to the first gear of the transmission coupling part and is able to rotate together with the first gear of the transmission coupling part.

4. The power steering system for commercial electric vehicles according to claim 1, wherein, The rotation axis of the output shaft is perpendicular to the rotation axis of the input shaft.

5. The power steering system for commercial electric vehicles according to claim 4, wherein, The rotation axis of the rotor of the electric motor is parallel to the rotation axis of the input shaft.

6. The power steering system for commercial electric vehicles according to claim 1, wherein, The toroidal worm gear transmission mechanism includes a toroidal worm gear that meshes with a toroidal worm wheel. The toroidal worm gear is positioned on the input shaft, and the toroidal worm wheel is positioned on the output shaft.

7. The power steering system for commercial electric vehicles according to claim 6, wherein, The toroidal worm gear includes multiple teeth distributed along an arcuate curve of not less than 120 degrees and not more than 200 degrees.

8. The power steering system for commercial electric vehicles according to claim 6, wherein, The power steering system for the commercial electric vehicle also includes a pair of bearings supporting the input shaft, wherein the toroidal worm gear is positioned on the input shaft between the pair of bearings.

9. The power steering system for commercial electric vehicles according to claim 8, wherein, Each of the pair of bearings is a tapered roller bearing.

10. A commercial vehicle, including the power steering system for commercial electric vehicles according to claim 1.

11. Power steering system for commercial electric vehicles, including: case; An input shaft, which is rotatably mounted within the housing; An electric motor, which is mounted to the housing; A planetary gear set, which is disposed within the housing and includes a sun gear, a plurality of planet gears, a planet carrier and a ring gear, wherein the sun gear of the planetary gear set is connected to the rotor of the electric motor and is capable of rotating together with the rotor of the electric motor; A transmission coupling unit is disposed within the housing and includes a first gear and a second gear. The planet carrier of the planetary gear set is connected to and rotatable with the first gear of the transmission coupling unit. The second gear of the transmission coupling unit is connected to the input shaft and rotatable with the input shaft. The transmission coupling unit also includes a belt or chain that couples the first gear of the transmission coupling unit to the second gear of the transmission coupling unit, or it may also include at least one additional gear that meshes with the first gear and the second gear of the transmission coupling unit. An output shaft, rotatably mounted within the housing; and A toroidal worm gear transmission mechanism is disposed within the housing and includes a toroidal worm gear meshing with a toroidal worm wheel. The toroidal worm gear is positioned on the input shaft, and the toroidal worm wheel is positioned on the output shaft. A Pittman arm, which is connected to the output shaft; Steering knuckle, the steering knuckle having a steering arm; as well as A tie rod that extends between and connects to the steering arm and Pittmann arm of the steering knuckle. The electric motor of the power steering system in the commercial electric vehicle is capable of operation, causing the steering knuckle to rotate.

12. The power steering system for commercial electric vehicles according to claim 11, wherein, The toroidal worm gear includes multiple teeth distributed along an arcuate curve of not less than 120 degrees and not more than 200 degrees.

13. The power steering system for commercial electric vehicles according to claim 11, wherein, The power steering system for the commercial electric vehicle also includes a pair of bearings supporting the input shaft, wherein the toroidal worm gear is positioned on the input shaft between the pair of bearings.

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