Fork position sensor structure
By installing the magnet into the piston shaft in the transmission and laying the Hall sensor using the circuit board, the problem of complex structure and high cost of the fork position sensor in the prior art is solved, and high-precision and low-cost fork position detection is achieved .
Patent Information
- Application Number
- CN201910528582.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2019-06-18
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2039-06-18
AI Technical Summary
The fork position sensor structure in existing transmissions has problems such as large space proportion, complex structure and high cost, and it is difficult to check after the sensor is damaged.
Design a fork position sensor structure, in which magnets are installed in the piston shaft of each group of forks, the piston shaft movement drives the magnet displacement, Hall chip induces magnetic field changes, outputs linear signals, and multiple Hall sensors are arranged using circuit boards to improve Space utilization and reduce costs.
It realizes a fork position sensor with simple structure, low cost, small space occupancy and high control accuracy, reducing costs and simplifying the inspection process.
Smart Images
Figure CN110131410B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a position sensor for an automobile, and in particular to a sensor structure for detecting the position of a shift fork in a gearbox. Background Art
[0002] In modern society, cars have become one of the preferred means of transportation for the public. Cars can be roughly divided into two types: automatic and manual. Of course, many cars now take into account the driving experience, and there are also manual and automatic cars. A transmission is installed in the car, and the transmission is used to achieve the switching of different gears.
[0003] The transmission shift fork is a component in the transmission used to push the synchronizer sleeve to engage and disengage with the shift gear to achieve transmission gear changes. The shift fork magnet assembly is a component in the transmission that is fixed to the shift fork and provides a magnetic field signal source. The position sensor is a component in the transmission that is used to monitor the shift fork magnet signal output and perform signal conversion.
[0004] In order to enable the transmission control system to monitor the position of the shift fork, the method currently adopted is to install a position sensor on the transmission housing and provide the position signal of the shift fork to the control system through the position sensor.
[0005] The specific solution is to install a magnet on the fork, and by moving the magnet and the fork together, change the magnetic field signal at the position of the position sensor, so that the control system can monitor the position of the fork. In order for the position sensor to accurately sense the magnetic field signal generated by the magnet, in addition to the raw materials used for the magnet itself, the magnetization process, the connection structure between the magnet and the fork, etc. will have a direct impact on the quality of the magnet signal.
[0006] For example, the Chinese patent: "Magnet fixing mechanism for shift fork position sensor (CN201720025218.1)" includes a magnet assembly and a magnet bracket; the magnet assembly is provided with a guide groove, and the top of the magnet bracket is provided with a concave support plate, and the magnet assembly is plug-in installed on the concave support plate of the magnet bracket through the guide groove. However, the problem with this structure is that since there are a large number of shift forks and they are far apart, it is necessary to install a magnet on each shift fork, and multiple separate sensors are required, which is costly and difficult to troubleshoot after the sensor is damaged. Summary of the invention
[0007] The present invention provides a fork position sensor structure with simple structure, high reliability, low cost, small space occupation and easy arrangement of components, and solves the technical problems existing in the prior art of large space occupation, complex structure and high cost.
[0008] The above technical problems of the present invention are solved by the following technical solutions: a fork position sensor structure, including a plurality of forks located in a gearbox, wherein at least two forks form a group, a piston shaft is connected to one end of each fork, a magnet is installed in the piston shaft, the piston shaft moves axially with the fork, each group of piston shafts corresponds to a control board, and a Hall chip corresponding to the magnet is arranged in the control board. The movement of the fork is converted into the movement of the piston shaft, and the movement of the piston shaft drives the displacement of the magnet therein, thereby changing the surrounding magnetic field change for the Hall chip to sense, and converting it into a linear signal output to the TCU, completing the reading of the displacement and position of the piston shaft. The original structure of the magnet installed on the fork is changed, and the magnet is installed in the piston shaft. The distance between the piston shafts can be designed and adjusted. At the same time, multiple Hall sensors can be arranged in one circuit board, and the space can be reasonably used. The various components are compactly arranged, the space utilization rate is improved, the cost is reduced, and the control accuracy is high, and the circuit board design is convenient for troubleshooting.
[0009] Preferably, there are four shift forks, two shift forks form a group, the piston shafts corresponding to the two shift forks in a group are parallel to each other and staggered, and the control board is located between the two piston shafts. A cylindrical magnet is installed in each of the two piston shafts in the same group, the distance between the center lines of the two magnets is not less than 37mm, and the distance between the upper end surfaces of the two magnets is not less than 14mm. To ensure that the magnetic field strength of the two magnets does not affect each other and the sensing accuracy of the Hall sensor is ensured, the MAXWELL magnetic simulation software is used to calculate the interlaced magnetic fields of the two magnets in space and the impact on the chip sensing point. Reduce mutual interference.
[0010] Preferably, an open slot is provided at one end of the shift fork, a clamping slot is provided on the piston shaft, and the end of the shift fork is clamped in the clamping slot of the piston shaft. The shift fork and the piston shaft are matched by the clamping slot and the open slot, which has a simple structure and is convenient for disassembly and connection between the two, and the axial displacement of the shift fork can also drive the axial movement of the piston shaft.
[0011] Preferably, the piston shafts are located in the same plane, the control board is higher than the plane where the piston shafts are located, and the height of the shift fork is greater than the height of the plane where the control board is located. The horizontal and vertical spaces are reasonably utilized to improve space utilization.
[0012] Preferably, the distance between the Hall chip and the magnet is 8-15 mm. On the premise of ensuring sufficient magnetic field strength, the chip position and other components are arranged more reasonably, and the space utilization rate is high.
[0013] Preferably, a blind hole is provided in the piston shaft, and the magnet is installed in the piston shaft and sealed with glue, which is convenient for processing and simple in process.
[0014] Preferably, the relative positions of the magnets corresponding to the forks in the same group are designed according to the magnetic field strength sensed by the Hall chip. After the first magnetic field strength of the first magnet corresponding to the first Hall chip is set, the magnetic field strength of the remaining magnets in the same group at the position of the first Hall chip is less than the set first magnetic field strength. This ensures that the magnets do not affect each other and ensures the accuracy of detection. For example, after the position of the first magnet is determined, the magnetic field strength at 12mm around the first magnet is 20mT, the first Hall chip is within this magnetic field range, and the magnetic field strength at the position outside 12mm is less than 20mT. According to the magnetic field simulation software design, it can be seen that the influence of the remaining magnets on the first Hall chip can be ignored, so the positions of the remaining magnets are designed to ensure that multiple magnets in the same group do not interfere with each other.
[0015] Therefore, the fork position sensor structure of the present invention has the following advantages: simple structure, two forks are arranged as a group, the movement of the forks drives the movement of the piston shaft, the two piston shafts share a control board, low cost and good controllability; the two piston shafts are parallel and staggered, and the control board is installed using the gap between the two piston shafts, which takes up little space and improves the convenience of installation. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a stereoscopic diagram of the fork position sensor structure of the present invention.
[0017] Figure 2 yes Figure 1 Stereoscopic image without the shift fork.
[0018] Figure 3 yes Figure 1 Top view with the fork and housing removed.
[0019] Figure 4 yes Figure 1 Schematic diagram of the shift fork inside.
[0020] Figure 5 yes Figure 1 Schematic diagram of the piston shaft inside. DETAILED DESCRIPTION
[0021] The technical solution of the invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.
[0022] Example:
[0023] like Figure 1 and 2 As shown in 3 and 4 , a fork position sensor structure includes a gearbox housing 4 , in which four forks 3 are arranged, two forks 3 form a group, one group of forks 3 is located on the left side of the gearbox housing 4 , and the other group of forks 3 is located on the right side of the gearbox housing 4 .
[0024] The lower end of each shift fork 3 is integrally formed with an arc-shaped opening groove 6. There is a piston shaft 2 corresponding to the lower side of the shift fork 3. Both ends of the piston shaft 2 are mounted on the shaft seat 1 on the gearbox housing. An annular clamping groove 8 is provided in the middle of the piston shaft 2. The shift fork 3 is connected to the piston shaft 2 through the cooperation of the opening groove 6 and the clamping groove 8. The shift fork 3 moves along the axis of the piston shaft 2, driving the axial movement of the piston shaft 2. A blind hole is provided at one end of the piston shaft 2. After a magnet 7 is installed in the blind hole, the magnet is sealed in the piston shaft 2 by glue injection. Thus, the movement of the piston shaft drives the movement of the magnet 7, and the magnetic field changes.
[0025] The two piston shafts 2 in one group are parallel to each other and staggered, the distance between the center lines of the magnets 7 located in the piston shafts 2 is not less than 37 mm, and the distance between the upper end surfaces of the two magnets 7 is not less than 14 mm, so as to ensure that the two magnets 7 will not affect each other.
[0026] A circuit board 5 is installed in the space between the two piston shafts 2. Two Hall sensors are installed on the circuit board 5. Each Hall sensor corresponds to a magnet in a group. The Hall sensor senses the change of the magnetic field, thereby determining the movement distance of the piston shaft, and thus the movement trajectory of the shift fork. The distance between the circuit board and the piston shaft is 10 mm.
[0027] The movement of the shift fork drives the piston shaft to move and guides the magnet inside the piston shaft to move. The shift fork position sensor senses the magnetic field change of the magnet and converts it into a linear signal output to the TCU to complete the reading of the displacement and position of the piston shaft.
Claims
1. A fork position sensor structure, characterized in that: The invention comprises a plurality of shift forks in a gearbox, wherein two shift forks form a group, a piston shaft is connected to one end of each shift fork, a magnet is installed in the piston shaft, the piston shaft moves axially with the shift fork, each group of piston shafts corresponds to a control board, the piston shafts corresponding to the two shift forks in a group are parallel to each other and arranged in a staggered manner, the control board is located between the two piston shafts, a Hall chip corresponding to the magnet is arranged in the control board, the relative positions of the magnets corresponding to the shift forks in the same group are designed according to the magnetic field strength induced by the Hall chip, after the first magnetic field strength of the first magnet corresponding to the first Hall chip is set, the magnetic field strength of the remaining magnets in the same group at the position of the first Hall chip is less than the set first magnetic field strength; a cylindrical magnet is installed in each of the two piston shafts in the same group, the distance between the center lines of the two magnets is not less than 37 mm, and the distance between the upper end surfaces of the two magnets is not less than 14 mm; the distance between the Hall chip and the magnet is 8 to 15 mm; the MAXWELL magnetic simulation software is used to calculate the influence of the interlaced magnetic field of the two magnets in space on the chip sensing point, to ensure that the magnetic field strengths of the two magnets do not affect each other, and to ensure the sensing accuracy of the Hall sensor.
2. The fork position sensor structure according to claim 1, characterized in that: There are four shift forks.
3. The fork position sensor structure according to claim 1 or 2, characterized in that: An open groove is arranged at one end of the shift fork, a clamping groove is arranged on the piston shaft, and the end of the shift fork is clamped in the clamping groove of the piston shaft.
4. The fork position sensor structure according to claim 1 or 2, characterized in that: The piston shafts are located in the same plane, the control board is higher than the plane where the piston shafts are located, and the height of the shift fork is greater than the height of the plane where the control board is located.
5. The fork position sensor structure according to claim 1 or 2, characterized in that: A blind hole is provided in the piston shaft, and the magnet is installed in the piston shaft and sealed with glue.