Two-speed electrified transmission system

Abstract

A system for an electric transmission is provided herein. In one example, an electric transmission system includes an electric machine driving an input shaft, a first wet clutch at a first end of a countershaft, and a second wet clutch at a second end of the input shaft. The first wet clutch is selectively engaged with the countershaft through a first clutch gear, and the second wet clutch is selectively engaged with the input shaft through a second clutch gear. The input shaft meshes with the second clutch gear, and the countershaft meshes with the first clutch gear. The electric transmission system also includes an output shaft rotationally coupled with the countershaft.

Description

Technical Field

[0001] The present disclosure generally relates to transmissions, and more specifically to a two-speed transmission for an electric vehicle. Background Art

[0002] Heavy vehicles, such as front loaders, can utilize an electric transmission system to generate power, which provides a highly attractive alternative in terms of hydrocarbon emissions compared to vehicles that rely solely on internal combustion engines for propulsion. Some electric transmission systems use multi-speed transmissions to increase the available gear ratios of the device. The transmission may include one or more shafts and gears that can engage or disengage with each other depending on the selected gear ratio.

[0003] A countershaft multi-speed transmission may include one or more friction clutches and associated gears that are operatively assembled on multiple shafts, including an input shaft, a countershaft, and an output shaft. The power of the input shaft is provided by a prime mover and transmitted to the output shaft through one or more friction clutches. High input speeds are typically compensated for by additional gears, shafts, etc., such as including an input reduction gear set.

[0004] The inventors have recognized various problems with this approach. For example, the increase in the number of components such as gears, shafts, and bearings, as well as the increase in housing complexity and size, can result in excessive packaging and increased weight. The large components as described above may not be suitable for a particular vehicle platform, for example, those vehicle platforms that require a small mounting distance between output interfaces such as flanges. In addition, the additional gears, shafts, and bearings may reduce the overall efficiency of the transmission system. Summary of the Utility Model

[0005] The inventors of the present document have recognized these problems and developed a two-speed transmission system that at least partially addresses these problems. In one embodiment, the method disclosed herein provides an electric transmission system that includes a two-speed countershaft transmission system. The system includes a first wet friction clutch positioned to selectively engage the countershaft and a second wet friction clutch positioned to selectively engage the input shaft. The input shaft can be driven by an electric motor of the electric transmission system, and the output shaft can be rotationally coupled to the countershaft to transmit power downstream. The input shaft is rotationally coupled to a first gear that meshes with a first clutch gear of the first wet friction clutch. The countershaft is rotationally connected to a second gear that meshes with a second clutch gear of the second wet friction clutch. When engaged, the first wet friction clutch rotationally couples the countershaft to the input shaft through a first engagement gear; when engaged, the second wet friction clutch rotationally couples the input shaft through a second engagement gear. Thus, by positioning the second wet friction clutch to selectively engage the input shaft, the electric transmission system can allow a high input speed from the electric motor and can reduce damage to the first wet friction clutch, thereby enabling the transmission system to operate with high efficiency by reducing the respective slip speeds of the first and second wet friction clutches when the clutches are disengaged.

[0006] In addition, the configuration of the electric transmission system allows for the addition of an intermediate shaft rotationally coupled to two additional gears without overly increasing the overall packaging size. The intermediate shaft can be disposed between the countershaft and the output shaft. Adding the intermediate shaft can enable the transmission system to achieve a higher overall torque ratio. Thus, the electric transmission system can be configured for various vehicle platforms or applications. The housing of the transmission can be configured to match the transmission with and / or without the additional intermediate shaft, thereby reducing manufacturing costs and production volumes.

[0007] The configuration of the electric transmission system allows for the removal, replacement, and / or swapping of the electric motor through an adapter flange connected to the input shaft. Thus, an electric motor suitable for the application or vehicle platform can be selected. The wet clutches of the transmission system can maintain good shift quality when using different electric motors and motor parameters (such as speed, torque, and / or inertia).

[0008] It should be understood that the above summary is provided to introduce in a simplified form concepts that are further described in the detailed description. It is not intended to identify the key or essential features of the claimed subject matter, the scope of which is uniquely determined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to embodiments that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A schematic diagram of an example vehicle is shown.

[0010] Figure 2Shows a schematic diagram of a two-speed transmission system according to the first embodiment.

[0011] Figure 3A Shows the power path in the gearbox in the first working gear of the two-speed transmission system.

[0012] Figure 3B Shows the power path in the gearbox in the second working gear of the two-speed transmission system.

[0013] Figure 3C Shows a relevant table of the operation gears and clutch engagement in the two-speed transmission system.

[0014] Figure 4 Shows a schematic diagram of a two-speed transmission system according to the second embodiment.

[0015] Figure 5A Shows a schematic diagram of the transmission housing of the two-speed transmission system.

[0016] Figure 5B Shows Figure 5A A schematic diagram of the transmission housing without a motor as described in

[0017] Figure 6 Shows a detailed schematic diagram of an exemplary wet friction clutch according to the present disclosure.

[0018] Figure 7 Shows a detailed schematic diagram of a two-speed transmission system according to the first embodiment.

[0019] Figure 8 Shows a detailed schematic diagram of a two-speed transmission system designed according to the second embodiment.

[0020] Figure 9 Is a flowchart of the operation method of the two-speed transmission system. Detailed implementation

[0021] This document describes an electric transmission system that includes a two-speed transmission system with two different gears, providing a compact package and an efficient system. In some examples, the two-speed transmission includes a two-speed gearbox that consists of two wet friction clutches for shifting and at least three shafts (including an input shaft, a countershaft, and an output shaft). The compact layout of multiple shafts, gears, and clutches in the system enables the system to achieve the required gear selection without unduly affecting the space efficiency of the system. The system also allows for the addition of a lay shaft with additional gears to increase the torque ratio, and thus can be integrated into vehicle platforms with higher required gear ratios. The electric transmission system also includes a prime mover, such as an electric motor that drives the input shaft. The first wet friction clutch can be disposed toward the first end of the countershaft and configured to selectively engage with the countershaft. The second wet friction clutch can be positioned toward the second end of the input shaft and configured to selectively engage with the input shaft. A first gear rotationally coupled to the input shaft can engage with a first clutch gear of the first wet friction clutch to form a first engagement. A second gear rotationally connected to the countershaft can engage with a second clutch gear of the second wet friction clutch to form a second engagement. The output shaft is rotationally coupled to the countershaft through a third gear rotationally coupled to the countershaft and a fourth gear rotationally coupled to the output shaft.

[0022] The transmission system described herein also allows for the addition of a lay shaft that can be rotationally coupled to the countershaft. The transmission system according to this second embodiment includes the same input shaft, countershaft, output shaft, first wet friction clutch, and second wet friction clutch, with the gear / clutch engagement arrangement remaining unchanged. A lay shaft can be added to be rotationally coupled to the third gear on the countershaft and the fourth gear on the output shaft through a fifth and a sixth gear, respectively. The third and fourth gears can have various sizes. For example, in the case of not including the lay shaft, the third and fourth gears can each have a first size, while in the case of including the lay shaft, the third and fourth gears can each have a different second size to engage with the fifth and sixth gears, respectively. The additional lay shaft and additional gears can provide a greater torque ratio. Thus, the transmission system with the variable configuration described herein can be used in various vehicle platforms. The housing of the transmission also includes an adapter flange that is coupled to the first end of the input shaft and can couple various different motors to the input shaft. The wet friction clutches can accommodate various motor parameters, such as torque, speed, and inertia, thereby enhancing the flexibility of the system.

[0023] Figures 1 - 3B and Figures 4 - 8Shows an example configuration of the relative positioning of various components. If the components shown in the figure are in direct contact or directly coupled to each other, then in at least one example, these components can be respectively referred to as being in direct contact or directly coupled. Similarly, in at least one example, components shown adjacent or contiguous to each other can be adjacent or contiguous to each other respectively. For example, components in face-to-face contact with each other can be referred to as face-to-face contact components. Another example is that in at least one example, components are placed separately from each other with only space in between and no other components, and can be referred to as being placed separately from each other. Also, components shown above / below each other, on opposite sides of each other, or on the left / right sides of each other relative to each other can be referred to as such components. In addition, as shown in the figure, in at least one example, the topmost component or component point can be referred to as the "top" of the component, and the bottommost component or component point can be referred to as the "bottom" of the component. The top / bottom, upper / lower, above / below used in this article can be relative to the vertical axis in the figure and are used to describe the relative positioning of the various elements in the figure with respect to each other. Thus, in one example, an element shown above other elements is vertically positioned above the other elements. For another example, the shapes of the elements depicted in the figure can be referred to as having these shapes (e.g., circular, straight, planar, curved, rounded, chamfered, beveled, or similar shapes). In addition, in at least one example, elements shown intersecting each other can be referred to as intersecting elements or intersecting each other. Also, in one example, an element shown inside or outside another element can also be referred to as an intersecting element.

[0024] Figures 5A - 8 Approximately drawn to scale. However, in other embodiments, other relative component sizes can also be used.

[0025] Now referring to the figure, Figure 1 Shows a schematic diagram of a vehicle system 106 that can obtain propulsion force from a motor 154 (such as a drive motor). In some examples, the vehicle system 106 can be a front-end loader or a compact wheel loader vehicle system. In one embodiment, the motor 154 can be a traction motor. The electric motor 154 receives electrical energy from a traction battery 158 and provides torque to the vehicle's rear wheels 155. For example, during a braking operation, the motor 154 can also operate as a generator to charge the traction battery 158. It should be understood that although Figure 1 the motor 154 is described as being installed in a rear-wheel drive configuration, other configurations can also be employed, such as installing the motor 154 in a front-wheel configuration, or in a configuration where a first output yoke or other interface drives the rear wheels 155 and a second output yoke or other interface drives the front wheels 156.

[0026] The electric motor 154 can be part of a transmission (to be further described herein). Additionally, the electric motor 154 can also be coupled to the outside of the transmission / gearbox housing. The transmission / gearbox can include at least one clutch and one or more shafts. The controller 112 can send signals to the actuator of the clutch to engage or disengage the clutch, thereby coupling or decoupling the power transmission of the electric motor 154 to various shafts and gears therein.

[0027] The controller 112 can form part of a control system 114. The control system 114 receives information from a plurality of sensors 116 and sends control signals to a plurality of actuators 181. For example, the sensors 116 can include a battery charge state sensor, a clutch pressure sensor, a speed sensor, etc. As another example, the actuators can include a clutch, etc. The controller 112 can receive input data from various sensors, process the input data, and trigger the actuator in response to the processed input data according to instructions or codes programmed therein corresponding to one or more routines.

[0028] Now look at Figure 2 , a schematic layout diagram of an exemplary power transmission system 200 is shown. For reference, Figure 2 and Figures 3A - 3B and Figures 4 - 8 an axis system is provided. The Y-axis can be a vertical axis (e.g., parallel to the axis of gravity), the X-axis can be a transverse axis (e.g., a horizontal axis), and / or the Z-axis can be a longitudinal axis. However, in other examples, these axes may have other orientations.

[0029] The electric transmission system 200 can include an electric motor 204 and a multi-speed transmission 201 (e.g., a two-speed electric transmission), and thus can be a multi-speed electric transmission system. The multi-speed transmission 201 can include two wet clutches (e.g., a first wet clutch 220 and a second wet clutch 224), an input shaft 206, a countershaft 208, an output shaft 210, and a plurality of gears that couple the components together. The electric motor 204 (e.g., Figure 1 the electric motor 154 in

[0030] The speed and torque of the electric motor 204 can be controlled by the inverter 202. The inverter 202 can be used to convert direct current (DC) to alternating current (AC), and vice versa. In some examples, the electric motor 204 and / or the inverter 202 can be a multi-phase device (e.g., a three-phase device), which can achieve higher efficiency compared to other types of electric motors. However, motors and inverters that can operate with more than three-phase currents are also envisioned.

[0031] In some examples, the input shaft 206 can be a rotor shaft for coupling the electric motor 204 to other components of the electric transmission system 200, thereby converting the power of the electric motor 204 into rotational power that can be used by the transmission. The electric motor 204 can be an electric traction motor. The input shaft 206 can receive power from the electric motor 204, and the input shaft 206 can transfer the power to downstream components according to the configuration and engagement / disengagement of the clutch. In some examples, the countershaft 208 can transfer the power flow of the input shaft 206 to the output shaft 210 and thus may not be directly connected to the electric motor 204.

[0032] The input shaft 206 can be rotatably connected to the first gear 212. The countershaft 208 can be rotatably connected to the second gear 214 and the third gear 216. The output shaft 210 can be rotatably coupled to the fourth gear 218. The first wet clutch 220 (e.g., the first wet friction clutch) can be disposed on the first end 290 of the countershaft 208 and can be configured to rotatably couple the input shaft 206 to the countershaft 208 through the first gear 212. The first wet clutch 220 can include one or more friction plates, and in some examples, the first wet clutch 220 can have a multi-plate (e.g., multi-disc) configuration. The first wet clutch 220 can further include a first clutch gear 222 that can selectively engage with the countershaft 208 according to signals from a control system (e.g., Figure 1 the control system 114 in) and the pressure of a hydraulic system. The first clutch gear 222 can engage with the first gear 212 to form a first engagement, such that when the first clutch gear 222 engages with the countershaft 208, the rotation of the first gear 212 will be rotationally transmitted to the first clutch gear 222 and then to the countershaft 208. The first wet clutch 220 can be fixedly connected to the second gear 214.

[0033] The second wet clutch 224 (e.g., the second wet friction clutch) may be disposed at the second end 292 of the input shaft 206 and may be configured to rotationally couple the input shaft 206 to the countershaft 208 via the second gear 214. The second wet clutch 224 may include one or more friction plates and, in some examples, the second wet clutch 224 may have a multi-plate configuration. The second wet clutch 224 may further include a second clutch gear 226 that may be selectively engaged with the input shaft 206 in accordance with a signal from the control system. The second clutch gear 226 may be engaged with the second gear 214 to form a second engagement such that when the second clutch gear 226 is engaged with the input shaft 206, rotation of the second clutch gear 226 transfers rotation to the second gear 214 and, in turn, to the countershaft 208. In some examples, the second wet clutch 224 may be fixedly connected to the first gear 212.

[0034] As described above, the third gear 216 is rotationally coupled to the countershaft 208 and may be engaged with the fourth gear 218 to transfer rotation from the countershaft 208 to the output shaft 210, and the fourth gear 218 is rotationally coupled to the output shaft 210. The output shaft 210 may be connected to or otherwise formed with one or more output interfaces 230 and, in some examples, there are two output interfaces 230. The output interfaces 230 may be disposed at either end of the output shaft 210. In some examples, the output interfaces 230 may be flanges, yokes, or similar components. The output interfaces 230 may be designed to mechanically connect to downstream transmission system components 232, such as shafts, joints, etc. that transfer mechanical power to a drive axle (not shown). Alternatively, the output interfaces 230 may directly transfer mechanical power to a drive axle or axle assembly that includes components such as a differential, axle shafts, and drive wheels.

[0035] All of the shafts described herein may extend horizontally, parallel to the X-axis, and all of the gears described herein may extend vertically, parallel to the Y-axis. In some examples, the input shaft 206 may extend through the first gear 212 and the second wet clutch 224, and the countershaft 208 may extend through the first wet clutch 220, the second gear 214, and the third gear 216. In some examples, the input shaft 206 may be vertically above the countershaft 208 and the output shaft 210, and the countershaft 208 may be vertically above the output shaft 210. The input shaft 206, the countershaft 208, and the output shaft 210 may be parallel to each other, which may provide the desired form factor for the transmission housing in which the electric transmission system 200 is located. Additionally, the parallel configuration may provide more support for bearing locations throughout the transmission.

[0036] The multi-speed transmission 201 may also include a plurality of bearings. Bearing 242 may support and facilitate the rotation of the input shaft 206, bearing 244 may support and facilitate the rotation of the countershaft 208, and bearing 240 may support and facilitate the rotation of the output shaft 210. Bearings 240, 242, and 244 may be tapered roller bearings, ball bearings, or other suitable types of bearings capable of withstanding high input speeds.

[0037] In the layout described herein, the first wet clutch 220 is located on the countershaft 208, and the second wet clutch 224 is located on the input shaft 206. When each wet clutch is in the open position (e.g., disengaged from its respective shaft), the slip speed can be reduced. Thus, since the second wet clutch 224 is located on the input shaft 206, a high input speed can be allowed, where when the first wet clutch 220 is disengaged, a performance degradation due to burning caused by the high input speed can be avoided in second gear (e.g., when the second wet clutch 224 is engaged). Additionally, reducing the slip speed can reduce drag, thereby improving the efficiency of the transmission system.

[0038] Furthermore, with the layout introduced herein, the number of gear engagements of the clutches can be reduced. As described above, when the first wet clutch 220 is engaged, the first engagement can occur between the first gear 212 and the first clutch gear 222, and the second engagement can occur between the countershaft 208 and the output shaft 210 (e.g., through the third and fourth gear engagements). When the second wet clutch 224 is engaged, the first engagement can occur between the second gear 214 and the second clutch gear 226, and the second engagement can occur between the countershaft 208 and the output shaft 210. For a two-speed transmission incorporating wet clutches, two gear engagements may be the minimum number of gear engagements allowed by the wet clutch slip speed. In this way, the efficiency of the electric transmission system 200 can be improved. Additionally, as Figure 6 described, with respect to the first and second wet clutches 220, 224, the charging pressure of each wet clutch can be provided axially to the respective shaft ends, which can minimize the rotational seal diameter, thereby minimizing the rotational seal drag and improving the efficiency of the electric transmission system 200.

[0039] A wet clutch, as described in this section, is included in the electric transmission system 200 to improve the flexibility of system use and shift quality. Compared to dog clutches, synchronizers, etc., the use of a wet friction clutch can avoid power interruptions during shift transients. By making limited readjustments to the wet clutch parameters, the shift quality of different electric system (such as motors and inverters) variants can be maintained. Other layouts that include different types of clutches (such as synchronizers or dog clutches) may require larger control parameter changes to maintain shift quality. In addition, the electric system has smaller changes and can be matched with these dog clutch or synchronizer-based systems. Therefore, the system described herein has greater flexibility. In this way, due to the flexibility of the electric transmission system 200, the system can be matched with different motors and used in various applications.

[0040] The layout of the electric transmission system 200 can allow for the addition of a fourth shaft. When a fourth shaft is included in the transmission, as follows Figure 4 As described, the overall torque ratio may be increased. The gearbox system may add and remove the fourth shaft depending on the application of the gearbox. The housing of the gearbox system may be configured to accommodate the first embodiment or the second embodiment and minimize the increase in overall package size.

[0041] Now watch Figure 3A and Figure 3B , the figure shows Figure 2 The power paths of the first and second gears of the electric transmission system 200 are shown. Figure 3A Specifically showing the power path for first gear, Figure 3B The power path for the second gear is specifically shown. The directionality of power transmitted through the electric transmission system 200 can be changed by selective clutch engagement, as will be described below. The multi-speed transmission 201 can allow one of two wet clutches to be engaged simultaneously. Figure 3C Table 300 in FIG. 1 shows the meshing conditions of the operating gears and clutches.

[0042] like Figure 3A As shown, in the power path of the first gear, power is transmitted from the motor 204 to the input shaft 206. Power is transmitted from the input shaft 206 to the first gear 212, and is transmitted to the first clutch gear 222 of the first wet clutch 220 through the first meshing. The first clutch gear 222 meshing with the counter shaft 208 transmits power to the counter shaft 208. The counter shaft 208 transmits power to the third gear 216, and the third gear 216 transmits power to the fourth gear 218, and finally to the output shaft 210. As described above, power is transmitted from the output shaft 210 to the output interface 230 and other downstream components.

[0043] like Figure 3BAs shown, in the power path of the second gear position, power is transmitted from the motor 204 to the input shaft 206. When the second clutch gear 226 engages with the input shaft 206, power is transmitted from the input shaft 206 to the second clutch gear 226 of the second wet clutch 224. Then, power is transmitted from the second clutch gear 226 through a second engagement to the second gear 214 and then to the countershaft 208. Power is transmitted from the countershaft 208 to the third gear 216 and then to the fourth gear 218. The fourth gear 218 transmits power to the output shaft 210, and the output shaft 210 then transmits the power to the output interface 230 and, as described above, to the downstream components.

[0044] Figure 3C Table 300 shown in Figure 3A and Figure 3B illustrates the operating gears and clutch engagements in the first and second gear positions. In the first gear position, the first wet clutch 220 is engaged and the second wet clutch 224 is disengaged. In the second gear position, the first wet clutch 220 is in the disengaged state and the second wet clutch 224 is in the engaged state. The engagement of the first and second wet clutches may include the respective clutch gears (e.g., the first clutch gear 222 of the first wet clutch 220 and the second clutch gear 226 of the second wet clutch 224) engaging with the respective shafts (e.g., the countershaft 208 or the input shaft 206 respectively).

[0045] Now refer to Figure 4 , which shows a schematic layout diagram of an exemplary electric transmission system 400. The electric transmission system 400 includes a motor 204 and a multi-speed transmission 401, which may be the same as the electric transmission system 200 but with an additional lay shaft 410 added. The multi-speed transmission 401 may include all the components of the multi-speed transmission 201, including the first wet clutch 220, the second wet clutch 224, the input shaft 206, the countershaft 208, the output shaft 210, the first gear 212, the second gear 214, the third gear 216, and the fourth gear 218. In the electric transmission system 400, the third and fourth gears 216, 218 may be different in size from those in the electric transmission system 200 to accommodate the lay shaft 410 and its gears. The multi-speed transmission 401 also includes other components, including the lay shaft 410, the fifth gear 420, and the sixth gear 422. The additional components of the multi-speed transmission 401 can be added to the multi-speed transmission 201 to form the multi-speed transmission 401, and moreover, the additional components can be removed from the multi-speed transmission 401 to return to the multi-speed transmission 201.

[0046] As Figure 2As described above, the electric motor 204 can be connected to and drive the input shaft 206. The speed and torque of the electric motor 204 can be controlled by the frequency converter 202. The first gear 212 can be rotatably coupled to the input shaft 206 and can mesh with the first clutch gear 222 of the first wet clutch 220. The first wet clutch 220 can be disposed on the first end 290 of the countershaft 208. The second wet clutch 224 can be disposed at the second end 292 of the input shaft 206. The second clutch gear 226 of the second wet clutch 224 can mesh with the second gear 214. The third gear 216 can be further rotatably coupled to the countershaft 208.

[0047] Referring to the electric transmission system 200, the third gear 216 is rotatably coupled to the fourth gear 218. In the electric transmission system 400, the third gear 216 meshes with the fifth gear 420. The fifth gear 420 can be rotatably coupled to the stub shaft 410. The stub shaft 410 is further rotatably coupled to the sixth gear 422. The sixth gear 422 can be rotatably coupled to (e.g., meshed with) the fourth gear 218, and the fourth gear 218 is rotatably coupled to the output shaft 210. As Figure 2 described above, the output shaft 210 can be coupled to the output interfaces 230 at both ends of the output shaft 210, and these interfaces are configured to interface with downstream components.

[0048] The stub shaft 410 can carry the gears of the electric transmission system 400 but is not directly connected to the motor 204 or the output end. The stub shaft 410 can be located below the countershaft 208 and above the output shaft 210 along the Y-axis to increase the distance between the countershaft 208 and the output shaft 210. The stub shaft 410 can be parallel to the input shaft 206, the countershaft 208, and the output shaft 210.

[0049] The electric transmission system 400 also includes a plurality of bearings. As Figure 2 described above, the rotations of the input shaft 206, the countershaft 208, and the output shaft 210 are respectively supported and facilitated by the bearings 242, 244, and 240. The rotation of the stub shaft 410 can be supported and facilitated by the bearing 454.

[0050] The clutch engagement and operation of the gears of the electric transmission system 400 can be similar to Figure 3CThe electric transmission system 200 described in , where in the first gear position, the first wet clutch 220 is engaged and the second wet clutch 224 is disengaged, and in the second gear position, the first wet clutch 220 is disengaged and the second wet clutch 224 is engaged. The power path in the first gear position may include power transmission that enters the first wet clutch 220 through the first gear 212, enters the countershaft 208 from the first wet clutch 220, enters the lay shaft 410 from the countershaft 208 through the third gear 216 and the fifth gear 420, and enters the output shaft 210 from the lay shaft 410 through the sixth gear 422 and the fourth gear 218. The power path in the second gear position may include power transmission that enters the second gear 214 through the second wet clutch 224, enters the countershaft 208 from the second gear 214, enters the lay shaft 410 from the countershaft 208 through the third gear 216 and the fifth gear 420, and enters the output shaft 210 from the lay shaft 410 through the sixth gear 422 and the fourth gear 218.

[0051] Compared with the electric transmission system 200, the additional lay shaft 410 in the electric transmission system 400 can enable the transmission to achieve a higher overall torque ratio, which may be required for certain vehicle applications. The housing of the transmission can be configured to accommodate the additional shaft and gears. As previously mentioned, the lay shaft 410 and the fifth and sixth gears 420, 422 can be removed from the electric transmission system 400. In this way, the transmission can be adjusted according to the required vehicle application and the transmission ratio requirements of the required vehicle application. For applications with smaller transmission ratio requirements, the transmission 201 can be used, which reduces the manufacturing and production requirements due to the reduced number of components and increased compactness.

[0052] Now looking at Figure 5A , an example of the transmission housing 500 is shown in the figure. Figure 5A It is drawn to scale, but other relative dimensions can also be used if needed. Figure 2 The electric transmission system 200 in or Figure 4 The electric transmission system 400 in can be installed in the transmission housing 500. Conceptually, the transmission housing 500 can be divided into an upper part 502 and a lower part 504. The upper part 502 can accommodate the input shaft and the countershaft, the first and second wet clutches, and the first, second, and third gears. The lower part 504 can accommodate the output shaft and the fourth gear thereon, as well as the lay shaft of the electric transmission system 400 and the fifth and sixth gears in the second embodiment.

[0053] In some embodiments, the electric motor 204 is installed inside the motor housing 506, and this housing is connected to the transmission housing 500 through an adapter flange, as Figure 5B described. From Figure 5AThe electric transmission system 200 (or electric transmission system 400), the electric machine 204, and the control system 114 are not visible in the view of the transmission housing 500 shown.

[0054] Figure 5A The axis of rotation 510 of the input shaft 206, the axis of rotation 512 of the countershaft 208, and the axis of rotation 514 of the output shaft 210 are described in Figure 5A . Each of the axes of rotation 510, 512, and 514 may be parallel to each other along a horizontal axis. The mechanical interface 508 (e.g., one of the output interfaces 230) may be one of two mechanical interfaces that coincide with the axis of rotation 514. Figure 5A The second mechanical interface, which is not visible in Figure 5A , may be disposed transversely opposite the mechanical interface 508.

[0055] The upper portion 502 may have a first width 520. The lower portion 504 may have a second width 522. The first width 520 may be greater than the second width 522, such that the distance between the output interfaces 230 (e.g., between the mechanical interfaces) is less than the length of the countershaft 208. In one use case, designing the transmission with such a width difference can enable the transmission to be more effectively integrated into a space-constrained vehicle platform, such as a front-end loader. Figure 5A The lowering device 524 of the transmission 201 is also shown.

[0056] Figure 5A The cutting plane A - A′ in Figure 5A represents Figure 6 the cross-sectional view in Figure 6 .

[0057] Figure 5B The transmission housing 500 with the electric machine 204 and the electric machine housing 506 removed is shown. In the view shown in Figure 5B An adapter flange 550 is depicted. The adapter flange 550 may be connected to or otherwise formed with the transmission housing 500 and the input shaft 206. The adapter flange 550 may be configured to connect the electric machine to the input shaft 206. The adapter flange 550 may be configured to couple with various electric machines having different generated input speeds, torques, ratios, etc. In this way, the electric machine can be decoupled from the transmission system, so that the electric machine can be replaced to meet the vehicle application requirements. In this way, the electric transmission system can be configured according to the electric machine parameters to adapt to various vehicle applications. The wet clutch in the transmission system can improve flexibility because changes in input speed, torque, and inertia can still result in good shift quality, while other types of clutches (such as dog clutches and / or synchronizers) require parameter adjustment.

[0058] Now refer to Figure 6, an example of a wet friction clutch 600 according to the present disclosure is shown in the figure. The wet friction clutch 600 can be an example of the second wet clutch 224 of the electric transmission systems 200 and 400. The wet friction clutch 600 can be coupled to the input shaft 606 and positioned towards one end of the input shaft 606, opposite to the motor driving the input shaft 606. The wet friction clutch 600 can be installed within the transmission housing, such as Figure 5A and Figure 5B the transmission housing 500 in

[0059] The wet friction clutch 600 can include one or more friction plates 602, a clutch gear 604, a piston 608, a spring 612, a lubrication passage 614, and a backpressure chamber 634. The lubrication passage 614 can be in fluid communication with a lubrication supply device and a chamber 626 for lubricating the bearing 620 through an inlet 630. The lubrication supply device can contain a fluid (such as engine oil) for lubricating and cooling the components of the wet friction clutch 600, including one or more friction plates 602. One or more friction plates 602 can adopt a multi-plate configuration. When the wet friction clutch 600 is in the engaged state, one or more friction plates 602 can be engaged by the fluid pressure applied on the piston 608, thereby achieving torque transmission. When the wet friction clutch 600 is disengaged, one or more friction plates 602 disengage from each other (e.g., frictional decoupling).

[0060] A second lubrication passage 616 arranged in parallel with the first lubrication passage 614 can be in fluid communication with an oil filling pressure inlet 632. When engaging or disengaging the wet friction clutch 600, the hydraulic pressure through the second lubrication passage 616 increases or decreases the pressure on the piston 608 respectively, causing the spring 612 to extend or compress respectively. The spring 612 can be located within the backpressure chamber 634, that is, between the piston 608 and the backpressure chamber cover 610. The backpressure chamber 634 can counteract the centrifugal load on the piston 608, because the pressure increase caused by the rotational speed behind the piston 608 can be compensated by an almost identical pressure increase on the other side of the piston 608, that is, the pressure acting on the piston in the backpressure chamber 634 is also opposite to the inflation pressure. The engagement of the piston 608 and the spring 612 can cause the clutch gear 604 to engage with the input shaft 606. The rotation of the clutch gear 604 can be supported by a bearing 622. In some examples, the bearing 622 can be a ball bearing.

[0061] The inflation pressure inlet 632 permits axial application of pressure. As a result, the shaft end diameter can be reduced because no torque passes through the shaft and thus no connection to other mechanical components is required. At the same rotational speed, a smaller seal diameter reduces drag. A rotary seal can be used to retain the lubricating fluid inside the clutch assembly. The smaller rotary seal diameter provided by the axial pressure reduces rotary seal drag, thereby improving the efficiency of the assembly and the overall system.

[0062] Now referring Figure 7 to Figure 8 Figures, examples of a power transmission system 200 and a power transmission system 400 are shown respectively. Thus, similar component numbers are used. As Figure 2 described, the electric transmission system 200 includes a plurality of shafts, including an input shaft 206, a countershaft 208, and an output shaft 210. A first wet clutch 220 (including a first clutch gear 222) is disposed on the countershaft 208 and is positioned toward a first end 290. A second wet clutch 224 including a second clutch gear 226 is mounted on the input shaft 206 and is positioned toward a second end 292. The first clutch gear 222 meshes with a first gear 212, and the second clutch gear 226 meshes with a second gear 214. The output shaft 210 can be rotationally coupled to a fourth gear 218, and in the electric transmission system 200, the fourth gear 218 can be rotationally coupled to a third gear 216 disposed on the countershaft 208, and in the electric transmission system 400, the fourth gear 218 can be rotationally coupled to a sixth gear 422 ( Figure 8 not shown in the figure). The sixth gear 422 can be disposed at a first end of a countershaft 410, and a fifth gear 420 can be disposed at a second end 292 of the countershaft 410.

[0063] As Figure 7 shown by the electric transmission system 200 and as Figure 8 shown by the electric transmission system 400, examples show the longitudinal axis of the system. As an example, the input shaft 206 can be parallel to the countershaft 208 along a transverse axis, perpendicular to the countershaft 208 along a longitudinal axis, and offset from the countershaft 208 along the longitudinal axis. In some examples, the input shaft 206 can be closer to the vehicle's rear than the countershaft 208. In other examples, the input shaft 206 can be closer to the vehicle's front than the countershaft 208. Similarly, the output shaft 210 can be longitudinally offset from the countershaft 208 and / or the input shaft 206.

[0064] Furthermore, as Figure 8As shown, the countershaft 410 can be longitudinally offset from the input shaft 206, the countershaft 208, and the output shaft 210. The longitudinal axis of the countershaft 410 may be closer to the longitudinal axis of the input shaft 206 relative to the longitudinal axes of the countershaft 208 and the output shaft 210. In this way, the countershaft 410 can be added to the electric transmission system 200 to form the electric transmission system 400 without unduly increasing the overall packaging size. The positions of the respective shafts can be configured according to the size and arrangement of the gears and / or clutches and the size and / or configuration of the transmission housing kit.

[0065] Figure 9 A flowchart is shown that illustrates a method 900 of operating a power transmission system including a multi-speed power transmission system (such as a two-speed electric power transmission system). In one example, the method 900 can be performed by any electric transmission system or combination of electric transmission systems described herein. In other examples, the method 900 can be implemented by other suitable power transmission systems. Additionally, as previously described, the method 900 can be executed by a controller that includes a memory for storing method step instructions executable by a processor. Figures 1 - 8 In 902, the method 900 includes determining operating conditions. The operating conditions can include input device position (such as shift lever position), clutch configuration, gear position, accelerator pedal position, transmission input / output speed, motor speed, vehicle speed, vehicle load, ambient temperature, etc. The operating conditions can be determined through sensor inputs, modeling, look-up tables, and / or other suitable techniques.

[0066] In 904, the method 900 includes determining whether a power shift should be performed on the electric multi-speed transmission. In one example, such a determination can be made based on the vehicle speed exceeding a threshold. In other examples, the operator's interaction with the gear selector can initiate the power shift operation. If it is determined that a power shift should not be performed (NO at 904), the method 900 proceeds to 906, where the method 900 includes maintaining the current operating strategy of the transmission. Then, the method 900 can return to 900 to again determine the operating conditions and determine whether a power shift should be performed.

[0067]

[0068] ​Conversely, if it is determined that a power shift should be performed (YES at 904), method 900 proceeds to 908, where method 900 includes engaging the first clutch while disengaging the second clutch while maintaining power transfer from the electric motor to the transmission. The first clutch referred to in method 900 can be the first wet clutch 220 or the second wet clutch 224, depending on the determined operating conditions of the electric transmission system. Thus, the power shift can include shifting from a first gear to a second gear, where the second wet clutch 224 is engaged and the first wet clutch 220 is disengaged; or, shifting from the second gear to the first gear, where the first wet clutch 220 is engaged and the second wet clutch 224 is disengaged.

[0069] In some examples, the power shift can include increasing torque transfer through one of the clutches and decreasing torque transfer through the other clutch. Additionally, during the shift process, the electric motor rotationally coupled to the transmission system can peak in a relatively short time to maintain the torque at the transmission output at a substantially constant value or above a threshold.

[0070] One technical effect of the two-speed electric transmission system described herein is that the system provides higher efficiency because by positioning the second wet friction clutch to selectively engage the input shaft, the electric transmission system can allow for high input speeds from the electric motor and can reduce the degradation of the first wet friction clutch, thereby enabling the transmission system to operate with high efficiency by reducing the slip speed of each of the first and second wet friction clutches when the clutches are disengaged. Additionally, the wet clutches allow for the installation of various electric motors in the electric transmission system, thereby increasing flexibility. Further, while maintaining the overall structure compact, additional layshafts can be selectively added depending on the application, thereby increasing flexibility.

[0071] The present disclosure also provides support for a two-speed electrified transmission system, which includes: an electric motor driving an input shaft; a first wet clutch disposed at a first end of a countershaft to selectively engage the countershaft with a first clutch gear; a second wet clutch disposed at a second end of the input shaft to selectively engage the input shaft with a second clutch gear, wherein the input shaft is engaged with the second clutch gear and the countershaft is engaged with the first clutch gear; and an output shaft rotationally coupled to the countershaft. In a first example of the system, the input shaft is rotationally coupled to a first gear engaged with the first clutch gear. In a second example of the system, optionally including the first example, the countershaft is rotationally coupled to a second gear engaged with the second clutch gear. In a third example of the system, optionally including one or both of the first and second examples, the countershaft is rotationally coupled to a third gear, and the third gear is rotationally coupled to the output shaft. In a fourth example of the system, optionally including one or more or each of the first to third examples, the third gear is engaged with a fourth gear, and the fourth gear is rotationally coupled to the countershaft. In a fifth example of the system, optionally including one or more or each of the first to fourth examples, the output shaft is connected to one or more output interfaces. In a sixth example of the system, optionally including one or more or each of the first to fifth examples, the system further includes: a lay shaft rotationally coupled to the countershaft through a fifth gear, and a lay shaft rotationally coupled to the output shaft through a sixth gear. In a seventh example of the system, optionally including one or more or each of the first to sixth examples, the input shaft, the countershaft, and the output shaft are parallel to each other. In an eighth example of the system, optionally including one or more or each of the first to seventh examples, the input shaft is perpendicular to the countershaft, and the countershaft is perpendicular to the output shaft. In a ninth example of the system, optionally including one or more or each of the first to eighth examples, in a first gear position, the first wet clutch is engaged and the second wet clutch is disengaged. In a tenth example of the system, in a second gear position, optionally including one or more or each of the first to ninth examples, the second wet clutch is engaged and the first wet clutch is disengaged. In an eleventh example of the system, optionally including one or more or each of the first to tenth examples, the first and second wet clutches are multi-plate wet friction clutches.

[0072] The present disclosure also provides support for a method of operating a transmission system, the method comprising: performing a power shift between a first gear and a second gear by disengaging a first wet friction clutch and engaging a second wet friction clutch, and vice versa, wherein the transmission system comprises: an electric motor rotationally coupled to an input shaft, a countershaft rotationally coupled to the input shaft, and an output shaft rotationally coupled to the countershaft, wherein the first wet friction clutch selectively engages the countershaft and the second wet friction clutch selectively engages the input shaft. In a first example of the method, when the first wet friction clutch is engaged, the countershaft is rotationally coupled to the input shaft by a first gear engaged in the first gear. In a second example of the method, optionally including the first example, when the second wet friction clutch is engaged, the input shaft is rotationally coupled to the countershaft by a second gear engaged in the second gear. In a third example of the method, optionally including one or both of the first example and the second example, the transmission system further comprises a lay shaft rotationally coupled to the countershaft and the output shaft.

[0073] The present disclosure also provides support for a multi-speed electric transmission system, the system comprising: an electric traction motor rotationally coupled to an input shaft, and an electric transmission comprising a first wet clutch configured to selectively engage a countershaft; a second wet clutch configured to selectively engage the input shaft driven by the electric traction motor; and an output shaft rotationally coupled to the countershaft, wherein the first wet clutch rotationally couples the countershaft to the input shaft by a first gear when engaged, and the second wet clutch rotationally couples the input shaft to the countershaft by a second gear when engaged. In a first example of the system, the electric transmission is enclosed within a transmission housing. In a second example of the system, optionally including the first example, the electric traction motor can be disengaged from the input shaft by an adapter flange coupled to the input shaft. In a third example of the system, optionally including one or both of the first and second examples, the electric transmission is configured to add a lay shaft with two additional gears.

[0074] While the foregoing describes various embodiments, it should be understood that these embodiments are merely examples and not limitations. It will be apparent to those skilled in the relevant art that the disclosed subject matter can be embodied in other specific forms without departing from the spirit of the subject matter. Accordingly, the embodiments described above should be considered illustrative in all respects and not restrictive. Thus, the configurations and routines disclosed herein are exemplary in nature, and these specific examples should not be considered restrictive as many variations are possible. For example, the above techniques can be applied to power systems incorporating different types of propulsion sources (including different types of motors and / or internal combustion engines). The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of various systems and configurations, as well as other features, functions, and / or characteristics disclosed herein.

[0075] Note that the control and estimation routine examples contained herein can be used for a variety of powertrain, electric drive, and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in a non-transitory memory and can be executed by a control system that includes a controller in combination with an electronic controller, various sensors, actuators, and other transmission and / or vehicle hardware. Accordingly, the actions, operations, and / or functions described can be graphically represented as code to be programmed into the non-transitory memory of a computer-readable storage medium in an electric transmission system and / or vehicle system. The various operations, runs, and / or functions illustrated can be executed in the order illustrated, executed in parallel, or omitted in some cases. Also, the order of processing is not necessarily required to achieve the features and advantages of the examples described herein, but is provided for ease of illustration and description. One or more of the actions, operations, and / or functions illustrated can be repeated depending on the particular strategy used. One or more of the method steps described herein can be omitted if desired.

[0076] As used herein, the term "approximate" shall be understood to mean a range of plus or minus 5%, unless otherwise specified.

[0077] The following claims particularly point out certain combinations and subcombinations regarded as novel and non-obvious. These claims may refer to "a" element or "a first" element or equivalent thereof. These claims should be understood to include one or more such elements, neither requiring nor precluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or characteristics may be claimed by modifying this claim or presenting new claims in this application or a related application. These claims, whether broader, narrower, the same, or different in scope from the original claims, are also regarded as included in the subject matter of this disclosure.

Claims

1. A two-speed electrified transmission system, comprising a motor that drives an input shaft; a first wet clutch located at the first end of a countershaft, the first wet clutch selectively meshing the countershaft with a first clutch gear; a second wet clutch located at the second end of the input shaft, the second wet clutch selectively meshing the input shaft with a second clutch gear, wherein the input shaft is meshed with the second clutch gear, and the countershaft is meshed with the first clutch gear; and an output shaft rotatably connected to the countershaft.

2. The two-speed electrified transmission system according to claim 1, wherein the input shaft is rotatably coupled to a first gear meshing with the first clutch gear.

3. The two-speed electrified transmission system according to claim 1, wherein the countershaft is rotatably coupled to a second gear meshing with the second clutch gear.

4. The two-speed electrified transmission system according to claim 1, wherein the countershaft is rotatably coupled to a third gear, and the third gear is rotatably coupled to the output shaft.

5. The two-speed electrified transmission system according to claim 4, wherein the third gear meshes with a fourth gear, and the fourth gear is rotatably coupled to the countershaft.

6. The two-speed electrified transmission system according to claim 1, wherein the output shaft is connected to one or more output interfaces.

7. The two-speed electrified transmission system according to claim 1, further comprising a lay shaft rotatably coupled to the countershaft through a fifth gear and rotatably coupled to the output shaft through a sixth gear.

8. The two-speed electrified transmission system according to claim 1, wherein the input shaft, the countershaft, and the output shaft are parallel to each other.

9. The two-speed electrified transmission system according to claim 1, wherein the input shaft is perpendicular to the countershaft, and the countershaft is perpendicular to the output shaft.

10. The two-speed electrified transmission system according to claim 1, wherein, In the first gear position, the first wet clutch is engaged and the second wet clutch is disengaged.

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