Sensing system for sensing a position of a gear shaft
The present disclosure discloses a sensing system for sensing a position of a gear shaft. The present disclosure may implement determination of whether the gear shaft is at a reverse gear position, a forward gear position or a neutral gear position by: partitioning a magnet into a first length region magnet and a second length region magnet, wherein the first length region magnet and the second length region magnet have different magnetic field directions, sensing and generating an inductive electrical signal reflecting motions of the first length region magnet and the second length region magnet; storing, by a memory unit, a first type reference signal for the first length region magnet and a second type reference signal for the second length region magnet, which are sensed by simulation; and comparing, by a processing unit, the inductive electric signal against the first type reference signal and the second type reference signal, which reflect different gear positions, respectively. By arranging only one magnet and one set of circuitry mechanical elements to sense a position of the gear shaft, the sensing apparatus according to the present disclosure effectively implements detection of the neutral gear position and the reverse gear position of the gear shaft, which reduces the manufacturing cost and lowers the failure rate.
1. A sensing system for sensing a position of a gear shaft, the gear shaft being provided, in its axial direction, with a plurality of groups of gear positions, the plurality of groups of gear positions including a plurality of neutral gear positions arranged along the axial direction of the gear shaft and a plurality of pairs of motion gear positions oppositely arranged at two sides of the neutral gear positions, one of the motion gear positions being a reverse gear position, while the remaining being forward gear positions, the sensing system comprising:
a sensing magnet that is fixedly arranged on the gear shaft and moves with the gear shaft, wherein the sensing magnet is axially partitioned into a first length region magnet and a second length region magnet; a magnetic field direction of the first length region magnet at a side in contact with the gear shaft is a first polarity, while the magnetic field direction thereof at a side distant from the gear shaft is a second polarity; a magnetic field direction of the second length region magnet at a side in contact with the gear shaft is a second polarity, while the magnetic field direction thereof at a side distant from the gear shaft is a first polarity such that the magnetic field direction of the first length region magnet is opposite to the magnetic field direction of the second length region magnet; and
a sensing unit arranged to be capable of sensing a magnetic field change when the sensing magnet moves, wherein when the gear shaft has a position change upon operation, the sensing unit senses the magnetic field change of the sensing magnet and generates a corresponding inductive electrical signal, the inductive electrical signal being compared against a pre-determined reference inductive electrical signal to indicate whether the gear shaft is at a forward gear position or a reverse gear position.
2. The sensing system according to claim 1 , wherein:
the first length region magnet generates a first form of magnetic field change; and
the second length region magnet generates a second form of magnetic field change.
3. The sensing system according to claim 2 , wherein:
when the gear shaft moves to the remaining one or more groups of the forward gear positions, the sensing unit senses the first form of magnetic field change to indicate a corresponding forward gear position; and
when the gear shaft moves to the reverse gear position or a corresponding forward gear position, the sensing unit senses the second form of magnetic field change to indicate whether the gear shaft is located at the reverse gear position or the corresponding forward gear position.
4. The sensing system according to claim 1 , further comprising:
a memory unit configured for pre-storing a first type reference signal for the first length region magnet and a second type reference signal for the second length region magnet; and
a processing unit connected to the sensing unit and the memory unit, configured for transducing the magnetic change sensed by the sensing unit into an inductive electrical signal and comparing the inductive electrical signal against the first type reference signal and the second type reference signal, to thereby determine whether the gear shaft is at a forward gear position or a reverse gear position.
5. The sensing system according to claim 4 , wherein:
the first type reference signal is an inductive electrical signal generated by the sensing unit by simulating, in advance, sensing of motion of the first length region magnet; and
the second type reference signal is an inductive electrical signal generated by the sensing unit by simulating, in advance, sensing of motion of the second length region magnet.
6. The sensing system according to claim 5 , wherein:
the first type reference signal has a plurality of first signal reference values that represent positions of a plurality of forward gears;
the second type reference signal has a plurality of second signal reference values that represent positions of forward gears and the reverse gear; and
the processing unit transduces the magnetic field change sensed by the sensing unit into an inductive electrical signal and compares the inductive electrical signal against the plurality of first signal reference values and the plurality of second signal reference values to thereby distinguish between the forward gear positions and the reverse gear position.
7. The sensing system according to claim 6 , wherein:
when the inductive electrical signal is identical to one reference value in the plurality of first signal reference values and the plurality of second signal reference values or a difference between the inductive electrical signal and the reference value is within a specific range, the processing unit determines that the gear shaft is at a gear position corresponding to the reference value.
8. The sensing system according to claim 7 , further comprising:
an indicating circuit connected to the processing unit;
wherein when the processing unit determines that the gear shaft is at a forward gear position, the processing unit sets the indicating circuit to a first state; and
when the processing unit determines that the gear shaft is at the reverse gear position, the processing unit sets the indicating circuit to a second state.
9. The sensing system according to claim 8 , wherein the indicating circuit transmits a state electrical signal to a vehicle control system, for the vehicle control system to make an engine start or stop determination.
10. The sensing system according to claim 6 , wherein:
the neutral gear position is arranged within a first rotating angle along two sides of an axis of the gear shaft;
the sensing unit senses a magnetic field strength change within a neutral gear position range where the first length region magnet and the second length region magnet are located within the first rotating angle and generates a sensed electrical signal;
the first type reference signal further has a first neutral gear position reference value representing motion of the first length region magnet;
the second type reference signal also has a second neutral gear position reference value representing motion of the second length region magnet; and
the processing unit transduces a magnetic field change sensed by the sensing unit into the inductive electrical signal, and compares the inductive electrical signal against the first neutral gear position reference value and the second neutral gear position reference value; wherein when the inductive electrical signal is identical or substantially identical to the first neutral gear position reference value or the second neutral gear position reference value, the processing unit determines that the gear shaft is at the neutral gear position corresponding to the reference value.
11. The sensing system according to claim 1 , wherein:
the second length region magnet corresponds to the reverse gear position and a corresponding forward gear position; and
the first length region magnet corresponds to the remaining forward gear positions.
12. The sensing system according to claim 1 , wherein the first length region magnet and the second length region magnet are sequentially arranged along the axial direction of the gear shaft.
13. The sensing system according to claim 1 , wherein the sensing unit is arranged relative to the sensing magnet such that: when the gear shaft is at a selected neutral gear position, the sensing unit aligns with the sensing magnet along a radial direction of the gear shaft.
14. The sensing system according to claim 4 , wherein the first type reference signal and the second type reference signal do not overlap.
15. The sensing system according to claim 14 , wherein a maximum value of the first type reference signal is smaller than a minimum value of the second type reference signal.
16. The sensing system according to claim 1 , further comprising a memory unit configured for pre-storing a first type reference signal for the first length region magnet and a second type reference signal for the second length region magnet;
wherein the first type reference signal has a plurality of first signal reference values that represent positions of a plurality of forward gears;
wherein the second type reference signal has a plurality of second signal reference values that represent positions of forward gears and the reverse gear.