Method of monitoring electrical shaft torque
By monitoring the electric shaft torque using an electronic clutch and sensors, the problem of the discrepancy between the wheel end torque and the electric shaft output torque is solved, achieving torque monitoring with a high level of functional safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- UNITED AUTOMOTIVE ELECTRONICS SYST
- Filing Date
- 2023-11-07
- Publication Date
- 2026-07-10
AI Technical Summary
In existing technologies, due to the addition of electronic clutches, the torque at the vehicle wheel end and the output torque of the electric axle are not completely equal, which makes it impossible to meet the requirements of electric axle torque monitoring methods with high functional safety levels.
By continuously acquiring the vehicle's driving status and the position information of the drive switching mechanism, the electronic clutch controls the engagement or disengagement of the output end of the second electric shaft from the wheel. The position of the electronic clutch is monitored by combining Hall sensors and PWM sensors, and torque monitoring is performed in three zones.
The safety level of the electric axle monitoring solution has been improved, ensuring that the wheel-end torque reaches a high functional safety level and avoiding undesirable acceleration and deceleration phenomena.
Smart Images
Figure CN117325667B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of vehicle functional safety technology, and in particular to a method for monitoring electric axle torque. Background Technology
[0002] Electric vehicles typically use the rear axle as the constant power source for their on-demand four-wheel drive, while the front axle requires power output only when needed. When switching from four-wheel drive to two-wheel drive, there are three common implementation methods: First, the front axle drive motor uses zero-torque control, outputting no torque in two-wheel drive mode. The advantage of zero-torque control is reduced vehicle weight, saving on parts and development costs, but it also reduces driving range. Second, the front axle drive motor is replaced with an asynchronous motor. The advantage of asynchronous motors is that they do not generate braking torque during reverse towing, thus eliminating the need for additional control methods. However, asynchronous motors are less efficient than synchronous motors, and using two different drive motors requires significant development costs. Third, a disengagement device is added to the front axle to disengage it as needed, conserving battery power. Current disengagement devices are electronic clutches (eClutch).
[0003] The mechanical structure of an electronic clutch, such as Figure 1 As shown, its working principle is as follows: the motor converts the rotational motion of the motor into the linear motion of the shift fork through a two-stage parallel gear reduction and a camshaft, which drives the synchronizing ring of the synchronizer to engage and disengage, thereby controlling whether the torque at the electric shaft end is output to the wheel end. To meet the high functional safety level, the electronic clutch has two position sensors: one is a three-phase Hall sensor for detecting the position of the motor rotor, and the other is a PWM sensor for detecting the position of the shift fork.
[0004] The torque safety requirements proposed by the vehicle manufacturer essentially require the wheel-end torque to reach a high functional safety level. Due to the addition of the electronic clutch, the wheel-end torque and the electric axle output torque are not exactly equal.
[0005] Currently, there is no electric axle with an electronic clutch that can meet the torque monitoring requirements for high functional safety levels.
[0006] To address the aforementioned issues, a novel method for monitoring electric shaft torque is needed. Summary of the Invention
[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for monitoring electric shaft torque, which solves the problem that the torque at the end of the vehicle wheel and the output torque of the electric shaft are not completely equal due to the addition of an electronic clutch, and the safety level of the electric shaft torque monitoring method of the electronic clutch is insufficient.
[0008] To achieve the above and other related objectives, the present invention provides a method for monitoring electric shaft torque, comprising:
[0009] The driving state of the vehicle is continuously acquired. The driving state of the vehicle includes a two-wheel drive state controlled by the first electric shaft and a four-wheel drive state controlled by the first and second electric shafts. The method for switching the driving state of the vehicle includes: using a drive switching mechanism to move the output end position of the second electric shaft so that the output end of the second electric shaft engages or disengages from the wheels of the vehicle.
[0010] The position information of the drive switching mechanism is continuously acquired, and different torque monitoring methods for the second electric shaft are switched according to the position information.
[0011] Preferably, the drive switching mechanism is an electronic clutch, which includes a drive motor, a first gear connected to the output shaft of the drive motor, a camshaft, and a synchronizer; a second gear meshing with the first gear is fixedly connected to the camshaft, and the camshaft is also provided with a shift groove; the synchronizer includes a shift fork, a shift pin, and a synchronizer ring, one end of the shift pin is slidably engaged with the shift groove, the other end of the shift pin is fixedly connected to one side of the shift fork, and the synchronizer ring is fixedly connected to the other side of the shift fork, wherein the drive motor converts its rotational motion into linear motion of the shift fork through the first gear and the camshaft, so that the synchronizer ring engages or disengages with the drive shaft of the corresponding wheel, thereby controlling the torque output of the wheel; a sensor unit is used to acquire the position of the drive motor rotor and the position of the synchronizer.
[0012] The sensor unit is a first sensor installed at the drive motor, and the first sensor is used to obtain the position of the drive motor rotor and the position of the synchronizer.
[0013] Preferably, the first sensor is a Hall sensor.
[0014] Preferably, the method for monitoring electric shaft torque according to claim 2 is characterized in that: the sensor unit comprises a first sensor disposed at the drive motor and a second sensor disposed at the synchronizer, the first sensor being used to obtain the position of the drive motor rotor, and the second sensor being used to obtain the position of the synchronizer.
[0015] Preferably, the first sensor is a Hall sensor and the second sensor is a PWM sensor.
[0016] Preferably, the torque monitoring method includes:
[0017] Step 1: Continuously acquire the position of the electronic clutch and determine whether the position of the electronic clutch is located in the first region. When the electronic clutch is located in the first region, the torque of the second electric shaft is not transmitted to the wheel end. If so, switch to the first control method, which is not to monitor the torque of the second electric shaft.
[0018] Step 2: Continuously acquire the position of the electronic clutch and determine whether the position of the electronic clutch is located in the second region, wherein the second region is the position where the electronic clutch is in contact with the drive shaft portion of the wheel; if yes, then monitor the zero torque output of the drive motor; if no, then end the zero torque output monitoring of the drive motor.
[0019] Step 3: Continuously acquire the position of the electronic clutch and determine whether the position of the electronic clutch is located in the third region, wherein the third region is the position where the electronic clutch is in complete contact with the drive shaft of the wheel; if so, monitor the torque output of the second electric shaft.
[0020] Preferably, the synchronizer's movement trajectory is Z-shaped. The initial position of the synchronizer is defined as the disengagement fulcrum, the upper turning point of the movement trajectory is defined as the synchronization start point, a position between the synchronization start point and the disengagement fulcrum is defined as the disengagement point, the lower turning point of the movement trajectory is defined as the synchronization end point, a position between the synchronization end point and the synchronization start point is defined as the synchronization contact point, the end point of the movement trajectory is defined as the on-grid fulcrum, and a position between the synchronization end point and the on-grid fulcrum is defined as the on-grid point. The first region is the region between the disengagement fulcrum and the synchronization contact point; the second interval is the region between the synchronization contact point and the synchronization end point; and the third interval is the region between the synchronization end point and the on-grid fulcrum.
[0021] Preferably, steps one to three further include detecting the output torque of the second electric shaft to determine whether the output torque is within a safe range. If so, the second motor remains running; otherwise, the drive motor is turned off within a set time.
[0022] As described above, the method for monitoring electric shaft torque of the present invention has the following beneficial effects:
[0023] The electric shaft torque monitoring method of the present invention, which uses the position switching of an electronic clutch, improves the safety level of the electric shaft monitoring scheme. Attached Figure Description
[0024] Figure 1 The diagram shown is a schematic of the electronic clutch of the present invention.
[0025] Figure 2 The diagram shown is a schematic representation of the monitoring method of the present invention.
[0026] Figure 3 The diagram shows the movement trajectory of the electronic clutch of the present invention.
[0027] Figure 4 The diagram shown is a schematic of the monitoring method for switching based on the movement trajectory of the electronic clutch according to the present invention. Detailed Implementation
[0028] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0029] This invention provides a method for monitoring electric shaft torque, comprising:
[0030] The driving state of the vehicle is continuously acquired. The driving state of the vehicle includes a two-wheel drive state controlled by the first electric shaft and a four-wheel drive state controlled by the first and second electric shafts. The method for switching the driving state of the vehicle includes: using a drive switching mechanism to move the output end position of the second electric shaft so that the output end of the second electric shaft engages or disengages from the wheels of the vehicle.
[0031] The position information of the drive switching mechanism is continuously acquired, and different torque monitoring methods for the second electric shaft are switched according to the position information.
[0032] In an embodiment of the present invention, the first electric axle is the rear axle, and the second electric axle is the front axle. Electric vehicles with on-demand four-wheel drive typically use the rear axle as a constant power source, while the front axle requires power output on demand.
[0033] In an embodiment of the present invention, please refer to Figure 1The drive switching mechanism is an electronic clutch, which includes a drive motor 101, a first gear connected to the output shaft of the drive motor 101, a camshaft 104, and a synchronizer 107. A second gear meshing with the first gear is fixedly connected to the camshaft 104, and a shift groove 103 is also provided on the camshaft 104. The synchronizer 107 includes a shift fork 106, a shift pin 105, and a synchronizer ring. One end of the shift pin 105 is in sliding engagement with the shift groove 103, and the other end of the shift pin 105 is fixedly connected to one side of the shift fork 106. The synchronizer ring is fixedly connected to the other side of the shift fork 106. The drive motor 101 converts its rotational motion into linear motion of the shift fork 106 through the first gear and the camshaft 104, so that the synchronizer ring engages or disengages with the drive shaft of the corresponding wheel, thereby controlling the torque output of the wheel. A sensor unit is used to obtain the position of the rotor of the drive motor 101 and the position of the synchronizer.
[0034] Typically, the engagement and disengagement of the electronic clutch are driven by the drive motor 101. Generally, the position signal of the drive motor 101 can be obtained through an absolute position sensor or a relative position sensor. When the functional layer and functional monitoring layer of the controller in the second electric shaft detect a fault in the electronic clutch position signal, a fault response must be initiated within the fault tolerance time to prevent unintended actions of the drive motor 101.
[0035] The sensor unit is a first sensor 108 located at the drive motor 101. The first sensor 108 is used to obtain the position of the rotor of the drive motor 101 and the position of the synchronizer 107.
[0036] In an embodiment of the present invention, the first sensor 108 is a Hall sensor.
[0037] In an embodiment of the present invention, the method for monitoring electric shaft torque according to claim 2 is characterized in that: the sensor unit consists of a first sensor 108 disposed at the drive motor 101 and a second sensor 109 disposed at the synchronizer 107, the first sensor 108 being used to obtain the position of the rotor of the drive motor 101, and the second sensor 109 being used to obtain the position of the synchronizer 107.
[0038] In an embodiment of the present invention, the first sensor 108 is a Hall sensor and the second sensor 109 is a PWM sensor.
[0039] In an embodiment of the present invention, please refer to Figure 2 The methods for switching the drive switching mechanism from two-wheel drive to four-wheel drive include:
[0040] Step 1: Continuously acquire the position of the electronic clutch and determine whether the position of the electronic clutch is in the first region. When the electronic clutch is in the first region, the torque of the second electric shaft is not transmitted to the wheel end, which will not cause the whole vehicle to produce undesirable acceleration or deceleration, and will not violate the functional safety target. The failure at this time is a safety failure. If it is, switch to the first control method, which is not to monitor the torque of the second electric shaft.
[0041] Step 2: Continuously acquire the position of the electronic clutch and determine whether the position of the electronic clutch is located in the second region, where the second region is the position where the electronic clutch is in contact with the drive shaft of the wheel; if yes, then monitor the zero torque output of the drive motor 101; if no, then end the zero torque output monitoring of the drive motor 101.
[0042] Step 3: Continuously acquire the position of the electronic clutch and determine whether the electronic clutch is located in the third region, where the electronic clutch is in full contact with the drive shaft of the wheel; if so, monitor the torque output of the second electric shaft.
[0043] It should be noted that the drive switching mechanism switches the four-wheel drive mode to two-wheel drive mode in the following ways:
[0044] Step 1: Continuously acquire the position of the electronic clutch and determine whether the electronic clutch is located in the third region, where the electronic clutch is in full contact with the drive shaft of the wheel; if so, monitor the torque output of the second electric shaft.
[0045] Step 2: Continuously acquire the position of the electronic clutch and determine whether the position of the electronic clutch is located in the second region, where the second region is the position where the electronic clutch is in contact with the drive shaft of the wheel; if yes, then monitor the zero torque output of the drive motor 101; if no, then end the zero torque output monitoring of the drive motor 101.
[0046] Step 3: Continuously acquire the position of the electronic clutch and determine whether the position of the electronic clutch is in the first region. When the electronic clutch is in the first region, the torque of the second electric shaft is not transmitted to the wheel end, which will not cause the whole vehicle to produce undesirable acceleration or deceleration, and will not violate the functional safety target. The failure at this time is a safety failure. If it is, switch to the first control method, which is not to monitor the torque of the second electric shaft.
[0047] In an embodiment of the present invention, please refer to Figure 3The synchronizer 107 moves in a Z-shape. The initial position of the synchronizer 107 is defined as the disengagement pivot point 201. The upper turning point of the moving trajectory is defined as the synchronization start point 203. The position between the synchronization start point 203 and the disengagement pivot point 201 is defined as the disengagement point 202. The lower turning point of the moving trajectory is defined as the synchronization end point 205. The position between the synchronization end point 205 and the synchronization start point 203 is defined as the synchronization contact point 204. The endpoint of the moving trajectory is defined as the engagement pivot point 207. The position between the synchronization end point 205 and the engagement pivot point 207 is defined as... The position is at gear position 206; the first region is the area between the disengagement pivot point 201 and the synchronization contact point 204; the second region is the area between the synchronization contact point 204 and the synchronization end point 205, where the synchronization contact point 204 is the position where the first electric shaft torque will transmit torque to the wheel end, and is the actual position where the safety target may be violated due to undesired torque; the third region is the area between the synchronization end point 205 and the gear position pivot point 207, where, since the electronic clutch is fully engaged, it is equivalent to a rigid connection between the output end of the second electric shaft and the end of the vehicle wheel. It should be noted that the movement trajectory of the synchronizer 107 can also be other shapes (e.g., S-shaped), which are not specifically limited here.
[0048] In an embodiment of the present invention, steps one to three further include detecting the output torque of the second electric shaft and determining whether the output torque is within a safe range. If yes, the second motor remains running; otherwise, the drive motor 101 is turned off within a set time.
[0049] Please see Figure 4 The division of the three-segment monitoring zone depends entirely on the position of the electronic clutch. Therefore, in order to ensure that the wheel-end torque reaches a high functional safety level, the position of the electronic clutch also needs to reach the highest functional safety level required for wheel-end torque; otherwise, the torque value sent based on the position of the electronic clutch is unreliable.
[0050] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0051] In summary, the electric shaft torque monitoring method using the position switching of the electronic clutch of the present invention improves the safety level of the electric shaft monitoring scheme. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.
[0052] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.
Claims
1. A method for monitoring the torque of an electric shaft, characterized in that, include: The vehicle's driving state is continuously acquired, including a two-wheel drive state controlled by a first electric axle and a four-wheel drive state controlled by the first and second electric axles. The method for switching the vehicle's driving state includes: The output end of the second electric shaft is moved using a drive switching mechanism, so that the output end of the second electric shaft engages or disengages from the wheels of the vehicle. Continuously acquire the position information of the drive switching mechanism, and switch different torque monitoring methods for the second electric shaft according to the position information; The drive switching mechanism is an electronic clutch, which includes a drive motor; The torque monitoring method includes: Step 1: Continuously acquire the position of the electronic clutch and determine whether the position of the electronic clutch is located in the first region. When the electronic clutch is located in the first region, the torque of the second electric shaft is not transmitted to the wheel. If so, switch to the first control method, which is not to monitor the torque output of the second electric shaft. Step 2: Continuously acquire the position of the electronic clutch and determine whether the position of the electronic clutch is located in the second region, wherein the second region is the position where the electronic clutch is in contact with the drive shaft portion of the corresponding wheel; if yes, then monitor the zero torque output of the drive motor; if no, then end the zero torque output monitoring of the drive motor. Step 3: Continuously acquire the position of the electronic clutch and determine whether the position of the electronic clutch is located in the third region, wherein the third region is the position where the electronic clutch is in complete contact with the drive shaft of the wheel; if so, monitor the torque output of the second electric shaft.
2. The method for monitoring electric shaft torque according to claim 1, characterized in that: The electronic clutch further includes a first gear, a camshaft, and a synchronizer connected to the output shaft of the drive motor; a second gear meshing with the first gear is fixedly connected to the camshaft, and the camshaft is also provided with a shift groove; the synchronizer includes a shift fork, a shift pin, and a synchronizer ring, one end of the shift pin is in sliding engagement with the shift groove, the other end of the shift pin is fixedly connected to one side of the shift fork, and the synchronizer ring is fixedly connected to the other side of the shift fork, wherein the drive motor converts its rotational motion into linear motion of the shift fork through the first gear and the camshaft, causing the synchronizer ring to engage or disengage with the drive shaft of the corresponding wheel, thereby controlling the torque output of the wheel; the electronic clutch further includes a sensor unit, which is used to acquire the position of the drive motor rotor and the position of the synchronizer.
3. The method for monitoring electric shaft torque according to claim 2, characterized in that: The sensor unit is a first sensor installed at the drive motor, and the first sensor is used to obtain the position of the drive motor rotor and the position of the synchronizer.
4. The method for monitoring electric shaft torque according to claim 3, characterized in that: The first sensor is a Hall sensor.
5. The method for monitoring electric shaft torque according to claim 2, characterized in that: The sensor unit consists of a first sensor located at the drive motor and a second sensor located at the synchronizer. The first sensor is used to obtain the position of the drive motor rotor, and the second sensor is used to obtain the position of the synchronizer.
6. The method for monitoring electric shaft torque according to claim 5, characterized in that: The first sensor is a Hall sensor, and the second sensor is a PWM sensor.
7. The method for monitoring electric shaft torque according to claim 1, characterized in that: The first electric shaft is the rear shaft, and the second electric shaft is the front shaft.
8. The method for monitoring electric shaft torque according to claim 6, characterized in that: The synchronizer's movement trajectory is Z-shaped. The initial position of the synchronizer is defined as the disengagement fulcrum. The upper turning point of the movement trajectory is defined as the synchronization start point. A position between the synchronization start point and the disengagement fulcrum is defined as the disengagement point. The lower turning point of the movement trajectory is defined as the synchronization end point. A position between the synchronization end point and the synchronization start point is defined as the synchronization contact point. The end point of the movement trajectory is defined as the on-grid fulcrum. A position between the synchronization end point and the on-grid fulcrum is defined as the on-grid point. The first region is the region between the disengagement fulcrum and the synchronization contact point; the second region is the region between the synchronization contact point and the synchronization end point; and the third region is the region between the synchronization end point and the on-grid fulcrum.
9. The method for monitoring electric shaft torque according to claim 6, characterized in that: Steps one to three also include detecting the output torque of the second electric shaft to determine whether the output torque is within a safe range. If so, the drive motor remains running; otherwise, the drive motor is turned off within a set time.