Shift drum angle detecting device for transmission

Patent metadata

Field	Value
Publication number	US-11585649-B2
Application number	US-202017031264-A
Country	US
Kind code	B2
Filing date	Sep 24, 2020
Priority date	Sep 30, 2019
Publication date	Feb 21, 2023
Grant date	Feb 21, 2023

Abstract

A shift drum angle detecting device includes: a first angle sensor configured to output a first sensor output value corresponding to a shaft rotational angle of a first sensor shaft integrally rotating with a shift drum; and a second angle sensor configured to output a second sensor output value corresponding to a shaft rotational angle of a second sensor shaft rotating at an increased speed as a result of a speed increasing mechanism increasing the rotation of the first sensor shaft. A first sensor switching angle where the maximum value and the minimum value of the first sensor output value are switched and a second sensor switching angle where the maximum value and the minimum value of the second sensor output value are switched are set to be different from each other in rotational angle of the shift drum. Such device precisely detects any rotational angle of the shift drum.

First claim

What is claimed is:

1. A shift drum angle detecting device for a constant-mesh transmission including a main shaft holding a plurality of driving gears and a counter shaft holding a plurality of driven gears meshing with the plurality of driving gears, the shift drum angle detecting device comprising:
shift forks configured to engage with shifter gears of the driving gears and the driven gears;
a shift drum including an outer circumferential surface provided with lead grooves where one ends of the shift forks engage;
a first sensor shaft provided at the shift drum so as to integrally rotate with the shift drum;
a second sensor shaft configured to rotate at an increased speed as a result of a speed increasing mechanism increasing a rotation of the first sensor shaft by a predetermined speed increasing ratio;
a first angle sensor configured to output a first sensor output value corresponding to a shaft rotational angle of the first sensor shaft; and
a second angle sensor configured to output a second sensor output value corresponding to a shaft rotational angle corresponding to the second sensor shaft, wherein
the first sensor output value once switches between a maximum value and a minimum value at a first sensor switching angle per rotation of the shift drum,
the second sensor output value switches between a maximum value and a minimum value at a second sensor switching angle for a number of times corresponding to the speed increasing ratio of the speed increasing mechanism per rotation of the shift drum,
a rotational angle of the shift drum is detected using the first sensor output value and the second sensor output value input at predetermined timing, and
the first sensor switching angle and the second sensor switching angle are set to be different from each other in rotational angle of the shift drum.

2. The shift drum angle detecting device for a transmission according to claim 1 , wherein
when it is determined that the first angle sensor is detecting the first sensor switching angle, the rotational angle of the shift drum is detected according to a previous value of the detected rotational angle of the shift drum and a change amount of a second sensor angle obtained by converting the detected shaft rotational angle of the second angle sensor to a rotational angle of the shift drum, and
when it is determined that the second angle sensor is detecting the second sensor switching angle, the rotational angle of the shift drum is detected according to the previous value of the detected rotational angle of the shift drum and a change amount of a first sensor angle obtained by converting the detected shaft rotational angle of the first angle sensor to a rotational angle of the shift drum.

3. The shift drum angle detecting device for a transmission according to claim 1 , wherein the first sensor switching angle and the second sensor switching angle are both set within a rotational angle region including just a neutral position of the shift drum.

4. The shift drum angle detecting device for a transmission according to claim 3 , wherein
the shift drum is provided with a star-shaped cam configured to integrally rotate with the shift drum,
the star-shaped cam includes an outer circumferential surface where curved recessed parts respectively corresponding to the shift stages and sharpened projecting parts are alternately and continuously arranged in a circumferential direction,
the shift drum angle detecting device further comprises a detent mechanism including a roller and a biasing means, wherein the roller biased by the biasing means is pressed against the outer circumferential surface of the star-shaped cam and fits into the recessed part corresponding to a prescribed one of the shift stages of the star-shaped cam, to regulate the rotation of the shift drum and establish the prescribed shift stage, and
the first sensor switching angle is set between a rotational angle of a bottom position at a center of the recessed part at the neutral position of the star-shaped cam and a rotational angle of a vertex of one of the projecting parts positioned on both sides of the recessed part continuously, the first sensor switching angle being set toward the one projecting part.

5. The shift drum angle detecting device for a transmission according to claim 4 , wherein
the roller is rotatably held on an end of a detent arm configured to swing as being biased by the biasing means, and
in a state where the roller fits into the recessed part at the neutral position of the star-shaped cam, the first sensor switching angle is set to a rotational angle toward, out of the projecting parts positioned on both sides of the recessed part continuously, the projecting part on a farther side from a swing center of the detent arm.

6. The shift drum angle detecting device for a transmission according to claim 1 , wherein
in the shift drum, in the lead grooves formed at the outer circumferential surface, a lowermost-position shift stage on a shift-down end and an uppermost-position shift stage on a shift-up end are at an identical rotational angle position while axially displaced from each other, and
at start-up, when the shift drum is at a rotational position of the lowermost-position shift stage or the uppermost-position shift stage, whether the shift stage is the lowermost-position shift stage or the uppermost-position shift stage is determined by rotating the shift drum in one direction and determining whether or not switching of the shift stage is executed.

7. The shift drum angle detecting device for a transmission according to claim 2 , wherein the first sensor switching angle and the second sensor switching angle are both set within a rotational angle region including just a neutral position of the shift drum.

8. The shift drum angle detecting device for a transmission according to claim 2 , wherein
in the shift drum, in the lead grooves formed at the outer circumferential surface, a lowermost-position shift stage on a shift-down end and an uppermost-position shift stage on a shift-up end are at an identical rotational angle position while axially displaced from each other, and
at start-up, when the shift drum is at a rotational position of the lowermost-position shift stage or the uppermost-position shift stage, whether the shift stage is the lowermost-position shift stage or the uppermost-position shift stage is determined by rotating the shift drum in one direction and determining whether or not switching of the shift stage is executed.

9. The shift drum angle detecting device for a transmission according to claim 3 , wherein
in the shift drum, in the lead grooves formed at the outer circumferential surface, a lowermost-position shift stage on a shift-down end and an uppermost-position shift stage on a shift-up end are at an identical rotational angle position while axially displaced from each other, and
at start-up, when the shift drum is at a rotational position of the lowermost-position shift stage or the uppermost-position shift stage, whether the shift stage is the lowermost-position shift stage or the uppermost-position shift stage is determined by rotating the shift drum in one direction and determining whether or not switching of the shift stage is executed.

10. The shift drum angle detecting device for a transmission according to claim 4 , wherein
in the shift drum, in the lead grooves formed at the outer circumferential surface, a lowermost-position shift stage on a shift-down end and an uppermost-position shift stage on a shift-up end are at an identical rotational angle position while axially displaced from each other, and
at start-up, when the shift drum is at a rotational position of the lowermost-positio

Assignees

• Honda Motor Co Ltd

Inventors

• Adachi Jun
• Kojima Hiroyuki
• Tokito Akira
• Furusawa Yoshikazu

Classifications

• G01D5/165

  by relative movement of a point of contact {or actuation} and a resistive track · CPC title

• G01B7/30 Primary

  for measuring angles or tapers; for testing the alignment of axes · CPC title

• F16H63/18 Primary

  the final actuating mechanism comprising cams · CPC title

• F16H59/70

  dependent on the ratio established · CPC title