Gear absolute position sensor for manual transmission

The present invention provides a gear absolute position sensor assembly (GAPS) that senses the current absolute, position of the shift lever of a manual transmission. The sensor assembly provides data to an associated electronic controller such as an engine control module (ECM) regarding the current position of the shift lever, such as an engaged gear. The sensor assembly preferably comprises two Hall effect or other type of magnetic field (proximity) sensors in combination with an application specific integrated circuit (ASIC) which is supplied with data from the sensors, decodes the output of the sensors and provides an output identifying a specific engaged gear or neutral for use by vehicle or engine management electronics. The sensors are mounted proximate the shift linkage at a location where they can sense both rotation and translation.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/425,626, filed Dec. 21, 2010, which is hereby incorporated in its entirety herein by reference.

FIELD

The present disclosure relates to a gear absolute position sensor (GAPS) for manual transmissions and more particularly to a gear absolute position sensor for manual transmissions for engine speed matching and engine start-stop applications.

BACKGROUND

The trend of automatic motor vehicle transmissions for passenger cars, sport utility vehicles, pickup trucks and other consumer vehicles from substantially full hydraulic operation to operation under the control of an electronic transmission control module (TCM) and hydraulic actuators has been accompanied by both the desire and necessity of providing electronic linear position sensors which provide real time data to the transmission control module regarding the current positions of the actuators, the associated shift linkages and the clutches, brakes and gears acted upon. Such data is utilized by the transmission control module to confirm, for example, the commencement and completion of a shift and thus the overall state of the transmission. Such data is also useful for self-diagnosis of impending or actual component failure.

This trend has not been taken up by the other significant class of motor vehicle transmissions, namely, manual transmissions. As the name suggests, such transmissions are manually shifted by the vehicle operator. Since shift timing and gear selection are left to the vehicle operator, the incorporation of various sensors in a manual transmission has been viewed as not only unnecessary but as an invasion of the operator's freedom.

Nonetheless, it is apparent that data regarding the current operating state of a manual transmission can be utilized by associated electronic controllers to improve the overall driving experience. The present invention is so directed.

SUMMARY

The present invention provides a gear absolute position sensor assembly (GAPS) that senses the absolute, current shift lever position or chosen or engaged gear of a manual transmission. The sensor assembly provides data to an associated electronic controller such as an engine control module (ECM). The sensor assembly preferably comprises two Hall effect or other type of magnetic field (proximity) sensors in combination with an application specific integrated circuit (ASIC) which is supplied with data from the sensors, decodes the output of the sensors and provides an output identifying a specific engaged gear or neutral for use by vehicle or engine management processors. The sensors are mounted proximate the shift linkage at a location where they can sense both rotation and translation.

The sensor assembly may be utilized with four, five, six or more speed and gear ratio manual transmissions. Use of the sensor assembly enables engine and transmission speed matching which reduces clutch wear and provides improved shift quality. The sensor assembly also enables engine start-stop capability as well as remote start for a manual transmission by, inter alia, detecting when the transmission is in neutral. The sensors and the application specific integrated circuit also provide full diagnostic capability.

Thus it is an aspect of the present invention to provide an absolute gear position sensor assembly for a manual transmission.

It is a further aspect of the present invention to provide a gear absolute position sensor (GAPS) for a manual transmission.

It is a still further aspect of the present invention to provide an absolute gear position sensor assembly for a manual transmission having two magnetic proximity sensors.

It is a still further aspect of the present invention to provide an absolute gear position sensor assembly for a manual transmission having two Hall effect sensors.

It is a still further aspect of the present invention to provide an absolute gear position sensor assembly for a manual transmission having an application specific integrated circuit.

It is a still further aspect of the present invention to provide an absolute gear position sensor assembly for a manual transmission having two sensors mounted proximate the shift linkage.

It is a still further aspect of the present invention to provide an absolute gear position sensor assembly for a manual transmission having four, five, six or more speeds or gear ratios.

It is a still further aspect of the present invention to provide an absolute gear position sensor assembly for a manual transmission having full diagnostic capability.

DETAILED DESCRIPTION

With reference toFIG. 1, the relevant electrical, electronic and mechanical components of a motor vehicle having a manual transmission equipped with the present invention are illustrated and generally designated by the reference number10. The components10include a prime mover12which may be a gasoline, Diesel or flex fuel engine, or a hybrid or electric power plant. The prime mover12includes an output shaft14which drives a main friction clutch16which is typically, though not necessarily, engaged and disengaged by the vehicle operator (not illustrated). The main clutch16selectively provides drive torque to an input shaft18of a manual transmission20. The manual transmission20may be conventional and includes a housing22as well as shafts, gears and synchronizer clutches (all not illustrated) which cooperatively provide, for example, four, five, six or more forward speeds or gear ratios and reverse. The transmission includes an output shaft24which is coupled to a final drive assembly26which may include, for example, a propshaft, a differential assembly and a pair of drive axles. A driver interface28generally includes those controls and devices under the control of and operated by the vehicle operator (not illustrated).

The components10also include a plurality of electric and electronic sensors which provide real time data to an engine control module (ECM)30. For example, an electronic sensor (tachometer)32disposed in the prime mover12provides a signal representing the current speed of the output shaft14of the prime mover12. A transmission input speed sensor (TISS)34senses the instantaneous speed of the input shaft18of the manual transmission20. A transmission output speed sensor (TOSS)36senses the instantaneous speed of the output shaft24of the manual transmission20. A gear absolute shift position sensor assembly40according to the present invention includes an application specific integrated circuit44, the data output of which indicates the current position of a shift lever72. A clutch position sensor52senses the position of the main clutch16. A throttle position sensor54senses the instantaneous position of a throttle pedal (not illustrated). A brake pedal position sensor56sense the position of a brake pedal (also not illustrated). A body control module (BCM)60receives data from one or more control switches62and includes a data output to the engine control module30.

Referring now toFIGS. 2,3and4, attached to the exterior of the housing22of the manual transmission20is a shift linkage70. The shift linkage70includes a shift lever72which terminates in a shift ball or handle74that is engaged and manipulated by the vehicle operator. The shift lever72is moveable through a virtual or actual shift gate or “H” pattern76, illustrated inFIG. 4, which facilitates selection of, separates and creates tactile feedback for six forward gears or speed ratios and reverse. It should be understood, however, that the manual transmission20with which the present invention is utilized may incorporate and provide more or fewer gears or speed ratios. The shift lever72is disposed in a ball pivot78and coupled to a longitudinally oriented shaft80which is supported by various mounting members or brackets and bearings82which allow it to translate fore and aft and rotate about its axis.

Referring now toFIGS. 3,5A,5B and5C, the gear absolute position sensor assembly40includes a first arc magnet or ring92and a spaced apart second arc magnet or ring94, both secured to the longitudinally oriented shaft80. In the neutral position of the shift linkage70illustrated inFIG. 5A, a first Hall effect sensor96is disposed proximate, but preferably not in contact with the first arc magnet or ring92and a second Hall effect sensor98is disposed proximate, but preferably not in contact with, the second arc magnet or ring94. The outputs of the first Hall effect sensor96and the second Hall effect sensor98are fed directly to the application specific integrated circuit44which may be formed and assembled integrally with the sensors96and98into a unitary device. Alternatively, a single arc magnet or ring and a proximate single three dimensional (3D) Hall effect sensor may be utilized in place of the two rings92and94and the two one dimensional (1D) Hall effect sensors96and98.

It will be appreciated that the first and second arc magnets or rings92and94and the associated Hall effect sensors96and98may be mounted within the transmission housing22, through the transmission housing22or at any convenient location where the rings92and94may be attached to the shaft80and the sensors96and98mounted proximately. For example, they may be mounted within or near the bracket or bearing82illustrated inFIG. 2. As an alternative to Hall effect sensors, anisotropic magneto resistance (AMR), giant magneto resistance (GMR), permanent magnet linear contactless displacement (PLOD), linear variable displacement transformer (LVDT), magneto elastic (ME) or magneto inductive (MI) sensors may be utilized.

FIG. 5Billustrates the position of the shaft80when the shift lever72is in a forward position in the shift gate76, selecting, for example, reverse, first, third or fifth gears. Here, the first arc magnet or ring92is remote or spaced from both the first and the second Hall effect sensors96and98and the second arc magnet or ring94is in proximate, sensed relationship with the first Hall effect sensor96. Rotation of the shaft80and the second arc magnet or ring94adjacent the first Hall effect sensor96changes or modulates the magnetic field strength sensed by the first Hall effect sensor96and this information is utilized by the application specific integrated circuit44to provide a data signal indicating the absolute, current gear shift position, as described more fully below.

FIG. 5Cillustrates the position of the shaft80when the shift lever72is in a rearward position in the shift gate76, selecting, for example, second, fourth or sixth gears. Here, the second arc magnet or ring94is remote or spaced from both the first and the second Hall effect sensors96and98and the first arc magnet or ring92is in proximate, sensed relationship with the second Hall effect sensor98. Rotation of the shaft80and the first arc magnet or ring92adjacent the second Hall effect sensor98changes or modulates the magnetic field strength sensed by the second Hall effect sensor98and this information is utilized by the application specific integrated circuit44to provide a data signal indicating the absolute, current gear shift position, as described more fully below.

Referring now toFIG. 6, the actual forward and rearward translations and clockwise and counterclockwise rotations of the shaft80relative to the neutral position are presented for each of the six forward speed or gear ratio positions and reverse. It should be appreciated that the translations and rotations presented inFIG. 6are illustrative and exemplary only and that such numerical values may vary and be adjusted widely to accommodate various transmission sizes, configurations and designs including those having a different number of gears. It should also be appreciated that although the shift linkage70described herein functions with first selection (lateral) motion of the shift lever72followed by shift (longitudinal) motion (and first rotational motion of the shaft80and the magnet rings92and94and then longitudinal motion), the invention also encompasses a shift linkage70in which the shaft80and the magnet rings92and94first move longitudinally and then rotate in response to motion of the shift lever72.

Referring now toFIG. 7, a diagram corresponding to the shift gate or “H” pattern76illustrated inFIG. 4, presents the PWM duty cycle output of the application specific integrated circuit44in percent for each of the Hall effect sensors96and98as a function of the location of the shift lever72and the shaft80. Note, first of all, that for all neutral positions, the duty cycle output values for both the sensors96and98are identical, thus providing a useful integrity check on system and sensor operation. Second of all, in both forward positions in the shift gate pattern76, selecting, for example, reverse, first, third or fifth gears, as illustrated ifFIG. 5B, and rearward positions in the shift gate pattern76, selecting, for example, second, fourth and sixth gears, as illustrated inFIG. 5C, one of the outputs of the Hall effect sensors96and98is always zero; the second Hall effect sensor98in the first instance and the first Hall effect sensor96in the second instance.

Referring now toFIG. 8, a graph illustrates the actual continuous state output (PWM duty cycle in percent) of the application specific integrated circuit44from the first Hall effect sensor96along the horizontal (X) axis and the output of the application specific integrated circuit44from the second Hall effect sensor98along the vertical (Y) axis as the shaft80and the shift lever72move through the various positions of the shift gate pattern76while selecting one of the available gears or speed ratios. From this graph, as well as the data ofFIG. 7, it will be appreciated that not only each gear selection position has a unique numerical value or signature but also that as the shift lever72is moved and the shaft80is translated and rotated, the outputs of the Hall effect sensors96and98and the application specific integrated circuit44provide a continuously varying, essentially analog, signal that permits the engine control module30or other, similar device to infer not only the present location of the shift lever72and the shaft80but also their direction of motion and the speed of such motion.

It should be appreciated that the gear absolute position sensor assembly40of the present invention provides and enables several benefits and features. For example, it supports engine start-stop applications inasmuch as they require neutral position detection. The invention improves shift quality and reduces driveline clunk by facilitating the pre-synchronization of the driveline. Additionally, matching of the speed of the engine output and transmission input, which requires absolute gear position and the anticipated gear, is possible. Torque management which may reduce transmission mass and complexity is also possible. Remote, i.e., unattended, starting is also facilitated since it, too, requires neutral position detection. Furthermore, the invention may be utilized to reduce or substantially eliminate abuse of the transmission as it may be utilized to sense and prevent a potentially abusive operational event. Finally, the invention provides full diagnostic capability, for example, short to power, short to ground and open circuit.