Accelerator opening degree detection device

An accelerator opening degree detection device is equipped with: a rotor that is attached to the shaft of a handlebar and rotates in conjunction with the operation of an accelerator grip; magnets attached to the rotor; magnetic sensors that detect the magnetic force of the magnets; a case that houses the rotor and the magnetic sensors, and is attached to the handlebar; and a sensor holder to which the magnetic sensors are attached, and which is housed in the case on the opposite side of the rotor with respect to the accelerator grip. The sensor holder has an inner diameter protruding part that protrudes at a location opposing the magnets, this location being on the inside of the rotor in the circumferential direction, and the magnet sensors are arranged on the inner diameter protruding part.

TECHNICAL FIELD

The present invention relates to an accelerator opening degree detection device including magnetic sensors for detecting the rotational position of an accelerator grip (also referred to as an “opening degree of an accelerator grip”), which is angularly movably mounted on a handlebar of a saddle-type vehicle such as a two-wheeled vehicle or the like.

BACKGROUND ART

Saddle-type vehicles such as two-wheeled motor vehicles (including motorized bicycles) or the like, which are powered by an internal combustion engine, include an accelerator grip that is inserted into an end of a handlebar for engagement therewith. The accelerator grip comprises an inner tube having a flange, and a grip member in the form of a rubber member that covers the outside of the inner tube and is combined integrally therewith.

Japanese Laid-Open Patent Publication No. 2006-112284 discloses an accelerator opening degree detection device including a magnet circumferentially embedded in a flange of the inner tube of an accelerator grip. The flange of the inner tube is housed in a casing, which is made up of a pair of upper and lower casing members. The casing, which is fixedly mounted on the handlebar, also accommodates a magnetic sensor therein such as a Hall IC or the like.

When the accelerator grip is turned, the angular position of the magnet is changed, thereby causing a change in the magnetic force that is detected by the magnetic sensor.

An output signal of the magnetic sensor, which represents an accelerator opening degree, is supplied through wires to a controller, which controls the opening of a throttle valve, for example.

SUMMARY OF INVENTION

With the accelerator opening degree detection device disclosed in Japanese Laid-Open Patent Publication No. 2006-112284, since the magnetic sensor is disposed outside of a rotor that rotates in unison with the accelerator grip, the magnetic sensor is susceptible to external magnetic fields. Further, the accelerator grip tends to be large in size.

The present invention has been made in view of the aforementioned problems. It is an object of the present invention to provide an accelerator opening degree detection device, which is less susceptible to external magnetic fields, and does not make the accelerator grip large in size.

According to the invention recited in claim1, an accelerator opening degree detection device comprises a rotor mounted on a handlebar around an axis of the handlebar, the rotor being capable of being turned in unison with an accelerator grip as the accelerator grip is turned, a magnet mounted on the rotor, a magnetic sensor for detecting a magnetic force of the magnet, a case housing the rotor and the magnetic sensor, the case being mounted on the handlebar, and a sensor holder housed in the case at a position remote from the accelerator grip with the rotor interposed therebetween, the magnetic sensor being installed in the sensor holder, wherein the sensor holder includes an inner projected portion positioned radially inward of the rotor and projecting toward a position confronting the magnet, and wherein the magnetic sensor is disposed in the inner projected portion.

According to the invention recited in claim2, in the accelerator opening degree detection device of claim1, the magnetic sensor is housed in an inner space defined in the inner projected portion.

According to the invention recited in claim3, the accelerator opening degree detection device of claim1further comprises a back yoke mounted on the rotor radially outward of the magnet.

According to the invention recited in claim4, in the accelerator opening degree detection device of claim3, the back yoke has bent ends, which are bent radially inward from outside of opposite circumferential side edges of the magnet.

According to the invention recited in claim5, in the accelerator opening degree detection device of claim1, the magnet includes a first magnet and a second magnet, the magnetic sensor includes a first magnetic sensor and a second magnetic sensor, the first magnet and the second magnet are disposed in respective positions diametrically opposite to each other across the axis of the handlebar, the first magnetic sensor detects a magnetic force of the first magnet, and the second magnetic sensor detects a magnetic force of the second magnet.

According to the invention recited in claim6, the accelerator opening degree detection device of claim1further comprises a return spring having one end thereof supported in the rotor and another end thereof supported in the sensor holder, thereby normally biasing the rotor to move to a turning start point.

According to the invention recited in claim1, since the sensor holder with the magnetic sensor assembled therein and the case are separate from each other, the magnetic sensor can be installed on the handlebar without concern over how the case is placed in alignment with the handlebar. Therefore, the magnetic sensor can be installed with increased efficiency. The sensor holder has the inner projected portion, which is positioned radially inward of the rotor with the magnet assembled therein and projecting toward a position confronting the magnet, and the magnetic sensor is disposed inside the inner projected portion. Consequently, the accelerator opening degree detection device reduces the effect that an external magnetic field has on the magnetic sensor. Further, the component around the accelerator grip is not increased in size.

According to the invention recited in claim2, since the magnetic sensor is housed in an inner space defined in the inner projected portion, the rotor is prevented from being brought into contact with the magnetic sensor when the rotor is installed. As a result, the magnetic sensor and the magnet can easily be installed on the handlebar. Unlike the background art, the accuracy with which the magnetic sensor is installed with respect to the magnet does not depend on the dimensional accuracy of the case. In addition, the case is not susceptible to dimensional errors and backlash of the handlebar along the axis of the handlebar.

According to the invention recited in claim3, inasmuch as the back yoke is disposed inside the rotor at a position radially outward of the magnet, the external magnetic field, which adversely affects the magnetic force of the magnet, is blocked by the back yoke. Therefore, the effect that the external magnetic field has on the magnetic force is eliminated, whereby accuracy with which the magnetic sensor detects the magnetic force of the magnet is increased.

According to the invention recited in claim4, the back yoke has the bent ends, which are bent radially inward from outside of opposite circumferential side edges of the magnet. The back yoke with the bent ends is capable of blocking an external magnetic field over a wider area, and of eliminating external magnetic fields that adversely affect the magnetic force of the magnet. Consequently, accuracy with which the magnetic force of the magnet is detected by the magnetic sensor can be further increased.

According to the invention recited in claim5, the magnetic sensors are disposed in respective symmetric positions on an axis perpendicular to the axis of the handlebar. For example, a failure of one of the magnetic sensors can be judged by the other magnetic sensor. Therefore, the accuracy with which failure of the magnetic sensor can be judged to have occurred or not is increased.

According to the invention recited in claim6, since the return spring is not mounted on the case, the case can be removed without being affected by the return spring. Consequently, when the case is removed to perform maintenance, the case can easily be removed, and therefore maintainability is increased.

DESCRIPTION OF EMBODIMENTS

An accelerator opening degree detection device according to a preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1is a left-hand side elevational view of a saddle-type vehicle100such as a two-wheeled motor vehicle. The saddle-type vehicle100is in the form of a scooter-type electric two-wheeled vehicle having a low floor102. The saddle-type vehicle100has a rear wheel WR, which is rotatable by rotational power generated by an electric motor108that is housed in a swing arm106. The rear wheel WR has an axle104that is rotatably supported on a rear end portion of the swing arm106.

The saddle-type vehicle100has a vehicle body frame, not shown, which is covered by a vehicle body cover110made of synthetic resin that provides a vehicle body S. The vehicle body cover110includes a front cover112covering a front side of a head pipe, not shown, of the saddle-type vehicle100, a leg shield116joined to the front cover112for covering a front side of the legs of a rider seated on a rider seat114, a low floor102joined to a lower portion of the leg shield116on which the feet of the rider seated on the rider seat114can be placed, a pair of left and right floor side covers118hanging down from opposite sides of the low floor102, an under cover120interconnecting lower edges of the floor side covers118, a lower seat front cover122covering a front side of a lower portion of the rider seat114and rising up from the rear end of the low floor102, a pair of left and right side covers124covering opposite sides of the lower portion of the rider seat114and joined to opposite sides of the lower seat front cover122, and a rear cover126covering an upper side of the rear wheel WR and joined to the side covers124.

A headlight128is mounted on the front end of the front cover112, and a taillight130is mounted on the rear end of the rear cover126. A front fender132, which is disposed below the front cover112, is mounted on a front fork134that rotatably supports a front wheel WF. The front fender132is disposed in covering relation to an upper side of the front wheel WF. A rear fender136, which covers a rear upper side of the rear wheel WR, is joined to the rear cover126. A fender138also is mounted on a front portion of the swing arm106for covering a front upper side portion of the rear wheel WR.

A handle140is joined to an upper portion of the front fork134. The front wheel WF can be steered by the handle140. The handle140has a front portion covered with a handle cover142. A front carrier144is disposed in front of the front cover112. A luggage base146is disposed behind the rider seat114and above the rear cover126. A carrier148is disposed above the luggage base146.

The vehicle body frame of the saddle-type vehicle100includes a pivot plate150. A side stand152, which holds the vehicle body S in an upright position while being tilted to the left, is angularly and movably mounted on the pivot plate150. The swing arm106has a front portion, which is swingably supported on the pivot plate150. A main stand154is angularly and movably mounted on the front portion of the swing arm106.

As shown inFIG. 2, winkers156are disposed as a pair respectively on left and right sides of the headlight128. The winkers156are formed integrally with the headlight128in a unitary manner to constitute a lamp unit158. The front cover112includes first recesses160and second recesses162, which are inwardly concave. The front carrier144has holes defined therein, which correspond respectively to the first recesses160and the second recesses162. After the holes in the front carrier144have been positioned in alignment respectively with the first recesses160and the second recesses162, bolts are inserted therethrough in order to fix the front carrier144and the front cover122to the vehicle body frame. The headlight128has a housing164, which is teardrop-shaped in side elevation, and a lens166, which is circular in front elevation and is mounted on the front end of the housing164. An accelerator grip16is mounted on a right-hand side of the handle140. The electric motor108is energized so as to rotate at a speed that depends on the angle through which the accelerator grip16is turned by the rider.

FIG. 3is a view of an accelerator opening degree detection device10according to an embodiment of the present invention, which is incorporated in the saddle-type vehicle100. The accelerator opening degree detection device10includes a handlebar12, a case (casing)14mounted on the handlebar12, and the accelerator grip16, which is mounted on one end portion of the handlebar12.FIG. 3also shows a brake lever18that is mounted on the case14for facilitating understanding of the present invention, although the brake lever18does not have a direct bearing on the present invention. InFIG. 4and the following figures, the brake lever18and other components, which are not required for description of the present invention, are omitted from illustration.

FIG. 4is a fragmentary cross-sectional view taken along line IV-IV ofFIG. 3.FIG. 5is a perspective view, partially in cross section, of the accelerator opening degree detection device10shown inFIG. 4. Reference numeral20represents the axis (central axis) of the handlebar12.

As shown inFIGS. 4 and 5, the accelerator grip comprises a hollow throttle member24having a flange22, which is fitted over the hollow handlebar12, and a grip sleeve26made of resin or the like, and which is fixedly mounted on the outer circumferential surface of the throttle member24. The accelerator grip16is angularly movably (rotatably) mounted on the handlebar12. The case14houses therein a rotor28, which is disposed around the axis20of the handlebar12for angular movement in unison with the accelerator grip16as the rotor28turns in the direction indicated by the arrow a inFIG. 3, and a sensor holder32. The sensor holder32is of a hollow, substantially two-stepped cylindrical shape, and holds respective Hall ICs (magnetic sensors)30a,30bthereon. In other words, the case14serves as a casing that covers the rotor28and the sensor holder32in a protected manner. The sensor holder32is housed in the case14at a position remote from the accelerator grip16with the rotor28interposed therebetween.

The rotor28has a protrusion34that projects toward the sensor holder32. The protrusion34supports magnets36a,36band back yokes38a,38bthereon. The back yokes38a,38bare disposed on an outer circumferential side relative to the magnets36a,36b. The protrusion34, the magnets36a,36b, and the back yokes38a,38bare disposed radially outward of a hollow cylindrical member, which has a shorter radius (hereinafter referred to as an “inner projected portion32a”), of the sensor holder32, which is of a substantially two-stepped cylindrical shape. The Hall ICs30a,30bare disposed inside of an outer circumferential surface of the inner projected portion32a. The inner projected portion32aprojects toward a position that confronts the magnets36a,36b, at a location located inward of the circumferential direction of the rotor28(the protrusion34of the rotor28). The Hall ICs30a,30bare accommodated in an inner space32b, which is defined in the inner projected portion32a.

In this manner, the magnets36a,36band the back yokes38a,38bare disposed outside of the Hall ICs30a,30bin the sensor holder32. The Hall IC (first magnetic sensor)30adetects a magnetic force of the magnet (first magnet)36ain order to detect a turning angle of the rotor28(the opening degree of the accelerator grip16), whereas the Hall IC (second magnetic sensor)30bdetects a magnetic force of the magnet (second magnet)36bin order to detect a turning angle of the rotor28(the opening degree of the accelerator grip16). The back yokes38a,38bblock external magnetic fields that could adversely affect the magnetic forces of the magnets36a,36b, thus resulting in an increase in detection accuracy of the magnetic forces of the magnets36a,36bby the Hall ICs30a,30b.

The sensor holder32covers the Hall ICs30a,30b, so as to prevent the Hall ICs30a,30bfrom coming into contact with the outer components. A portion of the sensor holder32is interposed between the magnets36a,36band the Hall ICs30a,30b, thereby preventing the magnets36a,36band the Hall ICs30a,30bfrom coming into contact with each other. The sensor holder32also prevents the rotor28and the Hall ICs30a,30bfrom contacting each other in directions along the axis20.

The rotor28has a groove40defined therein, which houses a return spring42between the groove40and the sensor holder32, for normally biasing the rotor28to move in the direction indicated by the arrow b inFIG. 3. The return spring42has one end that engages and is supported by a hole44defined in the rotor28, and another end that engages and is supported by a hole46defined in the sensor holder32. The sensor holder32and the case14are fixed to the handlebar12by a bolt B. The bolt B also fastens the sensor holder32and the case14to each other. The case14comprises an upper case14aand a lower case14b. Detection signals, which are generated by the Hall ICs30a,30b, are transmitted over wires47to a controller such as an ECU (Engine Control Unit) or the like, which is mounted on the saddle-type vehicle. The upper case14ahas a mounting boss15on which a non-illustrated side mirror is mounted.

As shown inFIG. 6, the flange22of the throttle member24has recesses50,52, with a small flange sector54and a large flange sector56defined between the recesses50,52. The rotor28has a tooth58that projects toward the flange22and is positioned in the recess50. The upper case14ahas a stopper60that projects radially inward (toward the flange22) and is positioned in the recess52. The stopper60limits rotational movement of the accelerator grip16in the direction indicated by the arrow a, and also limits rotational movement of the accelerator grip16in the direction indicated by the arrow b.

As shown inFIG. 7, the rotor28also has a recess62defined therein. The lower case14bhas a stopper64for limiting rotational movement of the rotor28in the direction indicated by the arrow b under the bias of the return spring42. When an edge of the recess62abuts against the stopper64, the rotor28is prevented from rotating further in the direction indicated by the arrow b. When the rotor28abuts against the stopper64, the angular position of the rotor28is referred to as a turning start point. In other words, the rotor28is biased to return to the turning start point.

When the rider turns the accelerator grip16in the direction indicated by the arrow a, a first abutment surface54aof the small flange sector54moves in the direction of the arrow a, whereupon the first abutment surface54acomes into abutment against the tooth58. When the rider further turns the accelerator grip16in the direction of the arrow a, the small flange sector54and the tooth58move together in the direction of the arrow a. At this time, the rotor28turns and the Hall ICs30a,30bdetect the turning angle of the rotor28. When the rider turns the accelerator grip16to a certain angular position, a fully open abutment surface56aof the large flange sector56comes into abutment against a fully open stopper surface60aof the stopper60, thereby preventing the accelerator grip16from turning further in the direction of the arrow a.

Thereafter, when the rider subsequently releases the accelerator grip16(reverses the direction in which the accelerator grip16is turned), the small flange sector54and the tooth58are turned by the return spring42in the direction indicated by the arrow b. The rotor28and the accelerator grip16are turned in the direction of the arrow b until the edge of the recess62of the rotor28abuts against the stopper64, whereupon the rotor28is stopped at the turning start point. Even if the rotor28returns to the turning start point, the accelerator grip16continues to turn in the direction of the arrow b until a second abutment surface54bof the small flange sector54comes into abutment against an excessive return prevention stopper surface60bof the stopper60, at which time the rotor28stops turning. An interval between the position at which the second abutment surface54bof the small flange sector54abuts against the excessive return prevention stopper surface60bof the stopper60and the position at which the first abutment surface54aabuts against the tooth58is referred to as a play interval of the accelerator grip16. Accordingly, the tooth58serves to transmit turning movement of the accelerator grip16to the rotor28. The stopper60serves as a limiting member for limiting turning movement of the accelerator grip16(turning movement of the accelerator grip16in the direction of the arrow a, as well as turning movement of the accelerator grip16in the direction of the arrow b).

FIG. 8is a cross-sectional view taken along line VIII-VIII ofFIG. 4. The magnets36a,36bare disposed in respective positions, which are diametrically opposite to each other across the axis20of the handlebar12, and the magnets36a,36bare curved along the circumferential direction of the handlebar12. The back yokes38a,38bare disposed respectively on outer circumferential surfaces of the magnets36a,36b. The back yokes38a,38bopen centrally along the axis20. The back yokes38a,38bare curved along the circumferential direction of the handlebar12. The back yoke38ahas bent ends66a,66b, which are bent radially inward from outside of the opposite outer circumferential side edges of the magnet36a, and the back yoke38bhas bent ends68a,68b, which are bent radially inward from outside of the opposite outer circumferential side edges of the magnet36b. The back yokes38a,38bincluding the bent ends66a,66b,68a,68bthereof are capable of blocking an external magnetic field over a wider area, and of further eliminating an external magnetic field that adversely affects the magnetic forces of the magnets36a,36b, thereby resulting in a further increase in the accuracy with which the Hall ICs30a,30bare capable of detecting the magnetic forces of the magnets36a,36b. The back yokes38a,38bneed not necessarily open centrally along the axis20.

The opening degree of the accelerator grip16may be detected by either one of the Hall ICs30a,30b, whereas the other one of the Hall ICs30a,30bmay be used to judge whether or not the Hall IC used to detect the opening degree of the accelerator grip16has failed. For example, only the Hall IC30amay be used to detect the opening degree of the accelerator grip16, whereas the Hall IC30bmay be used to judge whether or not the Hall IC30ahas failed. If the opening degree of the accelerator grip16, which is detected by the Hall IC30a, and the opening degree of the accelerator grip16, which is detected by the Hall IC30b, differ from each other, then the controller can determine that the Hall IC30ahas failed.

A process of assembling the accelerator opening degree detection device10will be described below. After the sensor holder32with the Hall ICs30a,30bassembled therein has been fitted over the handlebar12from one end thereof and positioned on the handlebar12, the rotor28with the return spring42placed therein also is fitted over the handlebar12from the one end thereof and is mounted on the handlebar12. At this time, one end of the return spring42engages and is supported in the hole44defined in the rotor28, whereas the other end of the return spring42engages and is supported in the hole46defined in the sensor holder32.

Next, the accelerator grip16is fitted over the handlebar12from the one end thereof. When the accelerator grip16is fitted over the handlebar12, as shown inFIG. 6, the accelerator grip16is positioned such that the small flange sector54and the large flange sector56of the flange22sandwich the tooth58therebetween. Further, at this time, the accelerator grip16is positioned such that the tooth58is positioned in the recess50defined in the flange22.

Thereafter, the lower case14bis fitted over the sensor holder32, the rotor28, and the flange22of the accelerator grip16, such that the stopper64fits in the recess62defined in the rotor28(seeFIG. 7). In addition, the upper case14ais fitted over the sensor holder32, the rotor28, and the flange22of the accelerator grip16, such that the stopper60fits in the recess52defined in the flange22(seeFIG. 6). The upper case14a, the lower case14b, and the sensor holder32are fastened to the handlebar12by the bolt B, thereby completing assembly of the accelerator opening degree detection device10.

Since the sensor holder32with the Hall ICs30a,30bassembled therein and the case14are separate from each other, the Hall ICs30a,30bcan be installed on the handlebar12without concern over how the case14is placed in alignment with the handlebar12. Therefore, the Hall ICs30a,30bcan be installed with increased efficiency. The sensor holder32includes the inner projected portion32a, which is positioned radially inward of the rotor28with the magnets36a,36bassembled therein, and which projects toward the position confronting the magnets36a,36b, while in addition, the Hall ICs30a,30bare disposed on the inner projected portion32a. Consequently, the accelerator opening degree detection device10reduces the effect that the external magnetic field has on the Hall ICs30a,30b, and does not make the component (i.e., the case14) around the accelerator grip16large in size.

Since the Hall ICs30a,30bare housed in the inner space32bdefined in the inner projected portion32a, the rotor28is prevented from coming into contact with the Hall ICs30a,30bwhen the rotor28is installed. As a result, the Hall ICs30a,30band the magnets36a,36bcan easily be installed on the handlebar12. Unlike the background art, installation accuracy of the Hall ICs30a,30bwith respect to the magnets36a,36bdoes not depend on the dimensional accuracy of the case14, and the case14is not susceptible to dimensional errors and backlash of the handlebar12along the axis20of the handlebar12.

Inasmuch as the back yokes38a,38bare disposed in the rotor28at a radially outward position from the magnets36a,36b, external magnetic fields, which could adversely affect the magnetic forces of the magnets36a,36b, are blocked by the back yokes38a,38b. Thus, any effect that the external magnetic field may produce on the magnetic forces of the magnets36a,36bis eliminated, thereby enhancing accuracy with which the magnetic forces of the magnets36a,36bare detected by the Hall ICs30a,30b.

The back yokes38a,38binclude the bent ends66a,66b,68a,68b, which are bent radially inward from outside of the opposite circumferential side edges of the magnets36a,36b. The back yokes38a,38b, which include the bent ends66a,66b,68a,68b, are capable of blocking external magnetic fields over a wider area, and of eliminating external magnetic fields that adversely affect the magnetic forces of the magnets36a,36b, thereby resulting in a further increase in accuracy with which the Hall ICs30a,30bdetect the magnetic forces of the magnets36a,36b.

The magnets36a,36bare disposed in respective positions, which are diametrically opposite to each other across the axis20of the handlebar12. The Hall IC30adetects the magnetic force of the magnet36a, whereas the Hall IC30bdetects the magnetic force of the magnet36b. The Hall IC30amay be used to detect the angle of rotation of the rotor28, whereas the Hall IC30bmay be used to judge whether the Hall IC30ahas failed or not. Therefore, whether or not the Hall IC30ahas failed can be judged with increased accuracy.

Insofar as the return spring42is not mounted on the case14, the return spring42is not dislodged even at times that the case14is removed for maintenance. Consequently, the case14can easily be removed for improving ease of maintenance.

The present invention has been described above with respect to a preferred embodiment thereof. However, the technical scope of the present invention is not limited to the embodiment illustrated above. It will be obvious to those skilled in the art that various improvements or modifications can be made with respect to the aforementioned embodiment. It is apparent from the scope of the claims that configurations, which are based on such improvements or modifications, fall within the technical scope of the present invention. The parenthetical reference characters, which are referred to in the patent claims, correspond with the reference characters shown in the accompanying drawings for thereby facilitating understanding of the present invention. However, the present invention should not be construed as being limited to the elements denoted by such reference characters.