JP2008002609A - Key shift transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a key shift transmission having assured durability and accurately shifting gears. <P>SOLUTION: The key shift transmission 15 comprises: a shifter 92 movably installed along a transmission shaft 26; a key member 94 having an arm part 122 extending from a connection part 121 along the transmission shaft 26 and having a key projection part 123 engageable with transmission gears 87 to 89 formed at the end 122a of the arm part 122; and a spring member 96 which has the base part 125 fitted to the connection part 121 of the key member 94, also has a plate spring 126 extending from the base 125 along the arm part 122 to the bottom surface 102a of a guide groove in the state of non-contact with each other, and presses the key projection part 123 by the end pressing part 126a of the plate spring 126 in the direction that is engaged with the transmission gears 87 to 89. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a key shift transmission that performs a shift by selecting an arbitrary gear from a plurality of transmission gears and engaging the selected transmission gear with a drive transmission shaft.

Some working machines such as a walking lawn mower include a key shift transmission as a transmission for changing the traveling speed, and this key shift transmission is configured to be operated by a shift lever by an operator (for example, a patent) Reference 1).
Japanese Utility Model Laid-Open No. 1-98953 The key shift transmission of Patent Document 1 will be described with reference to the following figure.

FIG. 9 is a cross-sectional view showing a conventional key shift transmission.
In the key shift transmission 200, a boss member 202 is fitted to a wheel drive shaft (hereinafter referred to as “transmission shaft”) 201, and a plurality of transmission gears 203 (... Indicate a plurality) rotate on the boss member 202. A key member 204 that can be engaged with a plurality of transmission gears 203 is connected to a shifter 205, and the shifter 205 is slidably provided along a hollow shaft 206, and a shift fork 208 is connected to the shifter 205. ing.

The key member 204 is biased toward the plurality of transmission gears 203 by the spring force of the spring member 209.
Thus, the key protrusion 204a of the key member 204 is engaged with an arbitrary transmission gear 203 selected from the plurality of transmission gears 203, and the transmission gear 203 is connected to the boss member 202.

According to the key shift transmission 200, the shift fork 208 moves the shifter 205 along the hollow shaft 206 to select an arbitrary transmission gear 203 from the plurality of transmission gears 203, and the selected transmission gear. The key protrusion 204 a of the key member 204 is engaged with 203.
When the key protrusion 204 a is engaged with the transmission gear 203, the transmission gear 203 is connected to the boss member 202. Thereby, the rotation of the transmission gear 203 is transmitted to the transmission shaft 201 via the boss member 202.

By the way, the key member 204 and the spring member 209 are accommodated in the boss guide groove 202a of the boss member 202 or the hollow shaft guide groove 206a of the hollow shaft 206.
On the other hand, the spring member 209 is formed in a curved shape so that the central portion 209a protrudes, and the protruded central portion 209a is pressed against the bottom surface 202b of the boss guide groove 202a and the bottom surface 206b of the hollow shaft guide groove 206a. .

  The spring member 209 slides in the axial direction of the transmission shaft 201 together with the key member 204 in a state where the central portion 209a is pressed against the bottom surface 202b of the boss guide groove 202a and the bottom surface 206b of the hollow shaft guide groove 206a.

Here, since the hollow shaft 206 and the boss member 202 are formed as separate members, the central portion 209a of the spring member 209 may be particularly worn when passing through the boundary between the hollow shaft 206 and the boss member 202. is there.
Since the central portion 209a of the spring member 209 is worn, it may be difficult to ensure durability.

Furthermore, it is conceivable that the spring constant of the spring member 209 changes due to wear of the central portion 209a of the spring member 209.
Since the spring constant of the spring member 209 is changed, it is difficult to satisfactorily engage the key member 204 with each of the transmission gears 203.

  It is an object of the present invention to provide a key shift transmission that can ensure durability and can perform gear shifting accurately.

  In the first aspect of the invention, a plurality of transmission gears are rotatably provided on the transmission shaft, an arbitrary transmission gear is selected from the plurality of transmission gears, and the selected transmission gear is rotated integrally with the transmission shaft. In the key shift transmission that can change the speed of the shifter, a shifter that is movably provided along the transmission shaft and a connecting portion are connected to the shifter, and an arm portion extends from the connecting portion along the transmission shaft. A key member provided with a key protrusion that can be engaged with the transmission gear at the distal end of the arm portion, and a base portion is fitted into the connecting portion of the key member, and a leaf spring portion extends from the base portion along the arm portion. A spring member that extends in a non-contact state toward the speed change shaft, and that presses the key protrusion in a direction to engage the speed change gear with a tip pressing portion of the leaf spring part, and the key protrusion By engaging the transmission gear, the transmission gear The characterized in that connected to the transmission shaft.

  According to a second aspect of the present invention, the shifter is formed with the storage recess for storing the connecting portion and the base portion, and is slidable directly along the transmission shaft.

  According to a third aspect of the present invention, the connecting portion has a contact surface facing the base portion, and the contact surface faces the base portion toward the speed change gear in an engaged state where the key protrusion is engaged with the speed change gear. The key protrusion is formed so as to abut against the base in a shift state in which the key protrusion is retracted from the transmission gear.

  According to a fourth aspect of the present invention, in the leaf spring portion, a portion on the base side excluding the tip pressing portion is separated from the arm portion.

  In the invention which concerns on Claim 1, the leaf | plate spring part of a spring member is extended in the non-contact state from the base to the speed-change shaft side along the arm part of a key member. Then, the key protrusion is pressed in a direction to engage the transmission gear with the tip pressing portion of the extended leaf spring portion.

By keeping the leaf spring portion of the spring member in a non-contact state with respect to the transmission shaft side, wear of the leaf spring portion can be prevented. Thus, there exists an advantage that durability can be ensured by preventing abrasion of a leaf | plate spring part.
Furthermore, the spring constant of a leaf | plate spring part can be kept constant by preventing abrasion of a leaf | plate spring part. As a result, the key member can be satisfactorily engaged with the speed change gear, and there is an advantage that the speed change can be performed accurately.

In the invention which concerns on Claim 2, the connection part of a key member and the base part of a spring member are accommodated in the accommodation recessed part of a shifter. The shifter is configured to slide directly along the transmission shaft.
The shape of the shifter can be reduced by sliding the shifter directly along the transmission shaft.
By reducing the shape of the shifter, there is an advantage that the key shift transmission can be made compact.

In the invention which concerns on Claim 3, the contact surface of a connection part can be made to contact a base part in the speed change state which slides a shifter directly along a speed-change shaft. Therefore, it becomes possible to keep the base reinforced with the contact surface.
As a result, the base portion can be smoothly slid along the speed change shaft, and there is an advantage that the speed change operation can be performed satisfactorily.

In the invention which concerns on Claim 4, it formed so that the site | part by the side of a base part might be separated from an arm part among leaf | plate spring parts. Therefore, when the key protrusion is retracted from the engagement position of the transmission gear, there is no possibility that the movement of the key member is hindered by the leaf spring portion.
As a result, the key protrusion can be smoothly withdrawn from the engagement position of the transmission gear, and there is an advantage that the gear shifting operation can be performed satisfactorily.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. “Front”, “back”, “left”, and “right” indicate Fr as the front side, Rr as the rear side, L as the left side, and R as the right side according to the direction viewed from the operator.
In the embodiment, an example in which the key shift transmission according to the present invention is provided in a walking lawn mower will be described. However, the use of the key shift transmission according to the present invention is not limited to a walking lawn mower. Absent.

FIG. 1 is a perspective view showing a walking lawnmower provided with a key shift transmission according to the present invention.
The walking lawnmower 10 includes left and right front wheels 11 at the front portion of a fuselage (not shown) and left and right rear wheels 12 at the rear portion, and an engine 13 between the left and right front wheels 11 and the left and right rear wheels 12. A lawn mowing blade 14 is provided below the engine 13, a key shift transmission 15 is provided to transmit the rotation of the engine 13 to the left and right rear wheels 12, and an operation handle 17 is extended rearward from the machine body. is there.

  In the key shift transmission 15, the input shaft 24 protrudes upward from the upper portion of the case 21, a driven pulley 25 is provided at the upper end of the input shaft 24, and the rear wheel drive shaft 26 extends from the left and right sides of the case 21. A clutch arm 27 and a transmission arm 28 are provided on the upper portion of the case 21.

The case 21 is assembled in a sealed state by tightening the upper case 22 and the lower case 23 with bolts 31 (... indicates a plurality).
The driven pulley 25 is connected to the drive pulley 33 via the drive belt 32. The drive pulley 33 is provided on a drive shaft 34 connected to the engine 13.

A left gear 36 is provided at the left end of the rear wheel drive shaft 26, and the left gear 36 meshes with the left driven gear 37. The left rear wheel 12 is connected to the left driven gear 37 via the left axle 38.
A right gear 41 is provided at the right end of the rear wheel drive shaft 26, and the right gear 41 meshes with the right driven gear 42. The right rear wheel 12 is connected to the right driven gear 42 via the right axle 43.

The clutch arm 27 is connected to the clutch lever 46 via the clutch cable 45. The clutch lever 46 is swingably provided on the handle 17.
By operating the clutch lever 46, the clutch arm 27 is operated, and the key shift transmission 15 is switched between “clutch on” and “clutch off”.

The transmission arm 28 is connected to a transmission lever 48 via a transmission cable 47. The transmission lever 48 is provided on the handle 17.
By operating the shift lever 48, the shift arm 28 is actuated to shift the key shift transmission 15.

  According to the walking lawnmower 10, the drive shaft 34 rotates by driving the engine 13. As the drive shaft 34 rotates, the drive pulley 33 rotates and the lawn mowing blade 14 rotates. When the drive pulley 33 rotates, the input shaft 24 rotates via the drive belt 32 and the drive belt 32.

The rotation of the input shaft 24 is transmitted to the rear wheel drive shaft 26. The rotation of the rear wheel drive shaft 26 is transmitted to the left rear wheel 12 via the left axle 38 and also transmitted to the right rear wheel 12 via the right axle 43.
Thus, grass such as turfgrass can be mowed by the lawn mowing blade 14 while being driven by the left and right rear wheels 12 and 12 and the left and right front wheels 11 and 11.
Hereinafter, the key shift transmission 15 will be described in detail.

FIG. 2 is a cross-sectional view showing a key shift transmission according to the present invention.
In the key shift transmission 15, a clutch mechanism 52 is provided on the intermediate shaft 51 in the sealed case 21, and a transmission mechanism is provided on the intermediate shaft 51 and the rear wheel drive shaft (hereinafter referred to as “transmission shaft”) 26 in the case 21. 53 is provided, and the case 21 is filled with lubricating oil.
That is, the clutch mechanism 52 and the transmission mechanism 53 are immersed in the lubricating oil.

The intermediate shaft 51 is rotatably supported by the case 21 through left and right intermediate shaft bushes 55 and 56 at the left and right end portions 51a and 51b, respectively.
The transmission shaft 26 is rotatably supported by the case 21 via left and right transmission shaft bushes 57 and 58, and extends to the outside of the case 21 from the left and right side portions 21a and 21b.

A through hole 61 is formed in the vicinity of the right transmission shaft bush 58 of the transmission shaft 26, and a retaining pin 62 is inserted into the through hole 61. A collar 63 is provided adjacent to the retaining pin 62.
The collar 63 includes a bent piece 63a that is bent from the outer periphery to the retaining pin 62 side. By arranging the bent pieces 63 a on both ends of the retaining pin 62, the retaining pin 62 is prevented from coming out of the through hole 61.

In the clutch mechanism 52, left and right cones 65, 66 are fitted on the intermediate shaft 51, and the left and right cones 65, 66 are locked to the intermediate shaft 51 by left and right lock pins 67, 68, respectively, and geared to the left and right cones 65, 66. 71 is fitted, a left thrust washer (thrust bearing) 72 is provided on the left side of the left cone 65, a right thrust washer (thrust bearing) 73 is provided on the right side of the right cone 66, and is pressed adjacent to the left thrust washer 72. A plate 74 is provided, and the cam 81 of the cam member 75 is in contact with the rear end portion 74 a of the pressing plate 74.
The clutch arm 27 is connected to the cam shaft 82 (see FIG. 1) of the cam member 75.

The gear ring 71 has a worm wheel 76 formed on the outer periphery and left and right inclined surfaces 77 and 78 formed on the inner periphery. A worm 79 is engaged with the worm wheel 76. The worm 79 is coaxially formed on the input shaft 24 (see also FIG. 1).
Therefore, when the input shaft 24 rotates, the worm 79 rotates and the rotation of the worm 79 is transmitted to the worm wheel 76.

In this state, the cam shaft 82 shown in FIG. 1 is operated by the clutch arm 27, and the pressing plate 74 is pressed against the left thrust washer 72 by the cam 81.
The inclined surface 65 a of the left cone 65 is pressed against the left inclined surface 77 of the gear ring 71, and the inclined surface 66 a of the right cone 66 is pressed against the right inclined surface 78 of the gear ring 71.
Thereby, the rotation of the gear ring 71 is transmitted to the intermediate shaft 51 via the left and right cones 65 and 66 and the left and right lock pins 67 and 68.

In the speed change mechanism 53, a plurality of first to third drive gears 84 to 86 are provided on the intermediate shaft 51, and first to third drive gears (speed change gears) are provided to the first to third drive gears 84 to 86. The first to third transmission gears 87 to 89 are rotatably attached to the boss member 90, the boss member 90 is attached to the transmission shaft 26, and a shifter 92 is provided on the right side of the boss member 90. The shifter 92 is provided with a key member 94 and a spring member 96 (see FIG. 3), and includes a shift fork 98 for operating the shifter 92.
The shift fork 98 is provided with a transmission arm 28 (see FIG. 1) via a transmission operation shaft 99.

  By operating the speed change lever 48 shown in FIG. 1, the speed change arm 28 is operated and the speed change operation shaft 99 is rotated. As the speed change operation shaft 99 rotates, the shift fork 98 swings around the speed change operation shaft 99. As the shift fork 98 swings, the shifter 92 slides along the transmission shaft 26.

3 is a cross-sectional view taken along line 3-3 in FIG. 2, FIG. 4 is a perspective view showing the main part of the key shift transmission according to the present invention, and FIG. 5 is an exploded perspective view showing the main part of the key shift transmission according to the present invention. FIG.
A boss member 90 is fitted into the transmission shaft 26. The boss member 90 is formed in a hollow cylindrical body, a flange portion 101 is formed at the right end, a pair of guide grooves 102, 102 extending in the longitudinal direction is formed on the outer periphery 90a, and an inner periphery 90b on the flange portion 101 side. A pair of recesses 103, 103 is formed.

The pair of guide grooves 102 and 102 are formed with an interval of 180 degrees. The pair of recesses 103 is formed with an interval of 180 degrees.
The pair of recesses 103 and 103 are formed at positions shifted by 90 degrees with respect to the pair of guide grooves 102 and 102.

The boss member 90 is fitted into the transmission shaft 26, and both ends 105a and 105a of the lock pin 105 (see also FIG. 2) are received in the pair of recesses 103. The lock pin 105 is passed through the through hole 106 of the transmission shaft 26.
Therefore, the boss member 90 rotates integrally with the transmission shaft 26.
A first transmission gear 87, a second transmission gear 88, and a third transmission gear 89 are rotatably fitted in the boss member 90.

The first transmission gear 87 is formed with four first engagement grooves 87a... At an interval of 90 degrees on the inner periphery.
The second transmission gear 88 is formed with four second engagement grooves 88a... At an interval of 90 degrees on the inner periphery.
In the third transmission gear 89, four third engagement grooves 89a are formed on the inner periphery at an interval of 90 degrees.
By forming four first to third engagement grooves 87a, 88a,..., 89a at intervals of 90 degrees, the key member 94 is fitted to two selected from the four.

As shown in FIG. 3, a first spacer 111 is disposed between the first transmission gear 87 and the flange portion 101. A second spacer 112 is disposed between the first transmission gear 87 and the second transmission gear 88. A third spacer 113 is disposed between the second transmission gear 88 and the third transmission gear 89.
A washer 114 is disposed between the left end portion of the boss member 90 and the left transmission shaft bush 57.

The shifter 92 is formed of a sintered alloy into a cylindrical body, and an inner peripheral surface 92a (see FIG. 5) is formed as a sliding surface. A pair of housing recesses 116 is formed on the inner peripheral surface 92a, and the outer peripheral surface 92b. An annular groove 117 is formed by machining.
The inner peripheral surface 92 a is a sliding surface that can slide with respect to the transmission shaft 26.
As an example, the sintered alloy is an alloy obtained by sintering powders of copper (Cu), carbon (C), and iron (Fe).

By forming the shifter 92 with a sintered alloy, the pores in the sintered alloy are exposed to the inner peripheral surface 92a and the recesses 93 (see FIG. 5) are formed.
The recesses 93 are fine recesses that do not prevent the inner peripheral surface 92a from sliding along the transmission shaft 26.

Lubricating oil can be stored in the recesses 93. This lubricating oil is filled in the case 21 shown in FIG.
By storing lubricating oil in the recesses 93, the lubricity of the inner peripheral surface 92a with respect to the transmission shaft 26 can be further enhanced.

By fitting the shifter 92 to the transmission shaft 26, the inner peripheral surface 92 a comes into contact with the transmission shaft 26. Therefore, when the shifter 92 is moved along the transmission shaft 26, the inner peripheral surface 92 a slides in a state of being in contact with the transmission shaft 26.
That is, the shifter 92 is a member that slides directly along the transmission shaft 26.

A pair of receiving recesses 116 are formed on the inner peripheral surface 92a with an interval of 180 degrees.
The pair of storage recesses 116 are recesses formed at the same time when the shifter 92 is formed of a sintered alloy.
Thereby, since the trouble of machining the pair of storage recesses 116 after molding the shifter 92 can be saved, the processing cost can be reduced and the productivity can be improved.

In the housing recess 116, the connecting portion 121 of the key member 94 and the base portion 125 of the spring member 96 are housed. The connecting part 121 is connected to the shifter 92, and the base part 125 is fitted in the connecting part 121.
Here, the upper and lower key members 94 are the same members. The upper and lower spring members 96 are the same member.
The connecting portion 121 of the key member 94 and the base portion 125 of the spring member 96 will be described later.

An annular groove 117 is formed on the outer peripheral surface 92 b of the shifter 92. A pair of pins 98 a and 98 a (see FIG. 4) provided on the shift fork 98 are inserted into the annular groove 117. By operating the speed change arm 28 with the speed change cable 47, the speed change operation shaft 99 rotates.
As a result, the shift fork 98 swings around the speed change operation shaft 99, and the shifter 92 is slid along the speed change shaft 26 in the longitudinal direction by the pair of pins 98a and 98a.

As described above, the shifter 92 is configured to house the connecting portion 121 of the key member 94 and the base portion 125 of the spring member 96 in the housing recess 116 and slide directly along the transmission shaft 26.
By directly sliding the shifter 92 along the transmission shaft 26, the shape of the shifter 92 can be reduced.
By reducing the shape of the shifter 92, the key shift transmission 15 can be made compact.

Further, by directly sliding the shifter 92 along the transmission shaft 26, a conventionally required hollow shaft (shown in the prior art in FIG. 9) needs to be interposed between the transmission shaft 26 and the shifter 92. There is no.
Thus, by removing the hollow shaft from the key shift transmission 15, the number of parts can be reduced, and the assembly work of the key shift transmission 15 can be easily performed.

The key member 94 is housed in the housing recess 116 of the shifter 92 and is connected to the shifter 92, an arm part 122 extending from the connection part 121 along the transmission shaft 26, and a tip part 122 a of the arm part 122. And a key protrusion 123 formed on the surface.
The connecting portion 121 includes a support portion 131 housed in the housing recess 116, a left protrusion 132 raised from the left end of the support portion 131 along the left wall 92 c of the shifter 92, and the shifter 92 from the right end of the support portion 131. And a right protrusion 133 raised toward the right wall 92d.

The connecting portion 121 includes an engaging recess 134 that can be engaged with the shifter 92 by being formed in a substantially U shape by the support portion 131, the left protruding portion 132, and the right protruding portion 133.
By engaging the engaging recess 134 with the shifter 92, the left protrusion 132 contacts the left wall 92c, and the right protrusion 133 contacts the right wall 92d.
As a result, the connecting portion 121 is housed in the housing recess 116 and kept in a state of being coupled to the shifter 92.

In addition, the engaging recess 134 is formed to be movable relative to the shifter 92.
Specifically, the key member 94 is swingable about the connecting portion 121 by connecting the engaging recess 134 to the shifter 92 so as to be relatively movable.
When the key member 94 swings around the connecting portion 121, the key protrusion 123 is engaged with the first to third transmission gears 87, 88, 89, and the first to third The shift gears 87, 88, 89 can be moved to the shift state retracted.

Further, the support portion 131 of the connecting portion 121 has a first contact surface 131 a and a second contact surface (contact surface) 131 b that face the base portion 125.
The first contact surface 131a and the second contact surface 131b are formed in an inclined shape so that a boundary portion 131c (see FIG. 6) between the surfaces 131a and 131b is a top portion.

  The first contact surface 131a abuts on the base 125 in the engaged state in which the key protrusion 123 is engaged with the first to third transmission gears 87, 88, 89 (see FIG. 3), and the key protrusion 123 is the first contact surface 131a. In the shift state retracted from the first to third transmission gears 87, 88, 89, the base portion 125 is separated (see FIG. 6B).

  The second contact surface 131b faces the first to third transmission gears 87, 88, and 89 when the key protrusion 123 is engaged with the first to third transmission gears 87, 88, and 89. The key protrusion 123 is separated from the base 125 (see FIG. 3), and abuts against the base 125 in the shift state in which the key protrusion 123 is retracted from the first to third transmission gears 87, 88, 89 (see FIG. 7B).

The arm portion 122 is a portion that extends along the axial direction (longitudinal direction) of the transmission shaft 26 from the left protrusion 132 of the connecting portion 121. A key protrusion 123 is formed at the tip 122a (see FIG. 5) of the arm 122.
The key protrusion 123 is formed in a substantially trapezoidal shape so as to be engageable with the first to third engagement grooves 87a, 88a, 89a.

The tip pressing portion 126a of the spring member 96 is brought into contact with the bottom surface 123a of the key protrusion 123. The key protrusion 123 is urged toward the direction away from the transmission shaft 26 by the urging force of the spring member 96.
Thereby, the key protrusion 123 can be engaged with the first to third engagement grooves 87a, 88a, 89a.
The key protrusion 123 and the arm portion 122 are disposed so as to be movable in the longitudinal direction in the guide groove 102.

FIG. 6 is a side view showing a key member and a spring member of the key shift transmission according to the present invention.
The spring member 96 includes a base portion 125 that can be fitted into the connecting portion 121, and a leaf spring portion 126 that extends from the base portion 125 so that the tip pressing portion 126 a abuts against the key protrusion 123.
The base 125 includes a sliding portion 127 that slides in the axial direction (longitudinal direction) in contact with the transmission shaft 26, a left upright piece 128 raised from the left end of the sliding portion 127, and a sliding portion 127. And a right upright piece 129 raised from the right end.
The base 125 includes a fitting recess 130 that can be fitted into the connecting portion 121 of the key member 94 by being formed in a substantially U shape by the sliding portion 127 and the left and right rising pieces 128 and 129.

The leaf spring portion 126 extends from the left standing upper piece 128 of the base portion 125 along the arm portion 122, and the key pressing portion 123 is moved to the first to third engagement grooves 87a, 88a, 89a ( (See FIG. 3).
That is, the leaf spring 126 is a member that urges the key protrusion 123 in a direction to engage with the first to third engagement grooves 87a, 88a, 89a.

Returning to FIG. 3, the leaf spring portion 126 extends in a non-contact state on the bottom surface 102 a of the guide groove 102 as a member on the transmission shaft 26 side.
By keeping the leaf spring portion 126 in a non-contact state with respect to the bottom surface 102a of the guide groove 102, wear of the leaf spring portion 126 can be prevented, and durability can be ensured.
Furthermore, by preventing wear of the leaf spring portion 126, the spring constant of the leaf spring portion 126 can be kept constant. Thereby, the key protrusion 123 of the key member 94 can be satisfactorily engaged with the first to third speed change gears 87 to 89, and the speed change can be performed accurately.

In addition, the leaf spring portion 126 is kept in a non-contact state with the bottom surface 102 a of the guide groove 102. By maintaining the spring member 126 in a non-contact state with the bottom surface 102a of the guide groove 102, no step is generated at the boundary between the bottom surface 102a of the guide groove 102 and the bottom surface of the hollow shaft (not shown) that has been conventionally required. There is no need to do so.
Thereby, it is not necessary to precisely process the bottom surface 102a of the guide groove 102 and the bottom surface of the hollow shaft that has been conventionally required, and the processing cost can be reduced.

Further, in the leaf spring portion 126, a portion 126 b excluding the tip pressing portion 126 a, that is, a portion 126 b on the base portion 125 side is separated from the arm portion 122.
The key member 123 is retracted from the engagement position of the first to third transmission gears 87 to 89 by separating the portion 126b on the base 125 side of the leaf spring portion 126 from the arm portion 122. There is no possibility of obstructing the movement of 94 by the leaf spring portion 126,
As a result, the key protrusion 123 can be smoothly retracted from the engagement position of the first to third transmission gears 87 to 89, and the speed change operation can be performed satisfactorily.

As for the leaf | plate spring part 126, the front-end | tip press part 126a is contact | abutted to the bottom face 123a of the key protrusion 123. FIG.
By bringing the tip pressing portion 126a of the leaf spring portion 126 into contact with the bottom surface 123a of the key projection 123, the key projection 123 is moved toward the first to third engagement grooves 87a, 88a, and 89a by the tip pressing portion 126a. Press. Therefore, the key protrusion 123 is engaged with the first to third engagement grooves 87 a, 88 a, and 89 a to connect the first to third transmission gears 87, 88, and 89 to the transmission shaft 26.

  Accordingly, by operating the speed change arm 28 with the speed change cable 47 shown in FIG. 4 and sliding the shifter 92 in the axial direction along the speed change shaft 26, the first to third speed change gears 87, 88, 89 An arbitrary transmission gear can be selected from among them, and the selected transmission gear can be rotated integrally with the transmission shaft 26.

Next, an example in which a shift operation is performed by the key shift transmission 15 will be described with reference to FIGS.
7 to 8, the upper key member 94 and the spring member 96 will be described, and the description of the lower key member 94 and the spring member 96 will be omitted.

FIGS. 7A and 7B are diagrams illustrating an example of shifting from the third transmission gear to the second transmission gear in the key shift transmission according to the present invention.
As shown in (a), the key protrusion 123 of the key member 94 is engaged with the third engagement groove 89 a of the third transmission gear 89.
The third transmission gear 89 can be rotated integrally with the transmission shaft 26 by engaging the key protrusion 123 with the third engagement groove 89a.

In a state where the key protrusion 123 is engaged with the third engagement groove 89a, the first contact surface 131a is kept in contact with the base 125.
In this state, the leaf spring portion 126 is kept in a non-contact state with the bottom surface 102 a of the guide groove 102, and the portion 126 b on the base 125 side is kept away from the arm portion 122.

From this state, the shifter 92 is slid along the transmission shaft 26 in the axial direction as indicated by an arrow A.
Here, the key member 94 is coupled to the shifter 92 so as to be swingable about the coupling portion 121.
Therefore, when the key protrusion 123 moves to the third spacer 113 side, the key protrusion 123 moves in the direction away from the third engagement groove 89a as shown by the arrow B against the urging force of the leaf spring portion 126. .

Here, recesses 93 are formed in the inner peripheral surface 92a of the shifter 92, and lubricating oil is stored in the recesses 93, so that the lubricity of the inner peripheral surface 92a with respect to the transmission shaft 26 can be further enhanced.
Thereby, the shifter 92 can be smoothly retracted from the engagement position of the third transmission gear 89.
Further, a portion 126 b on the base 125 side of the leaf spring portion 126 is kept away from the arm portion 122.
Thereby, the key protrusion 123 can be smoothly retracted from the engagement position of the third transmission gear 89 together with the shifter 92.

In (b), the top surface 123 b of the key protrusion 123 abuts on the inner periphery 113 a of the third spacer 113.
The first contact surface 131a is separated from the base 125, and the second contact surface 131b is kept in contact with the base 125.
The leaf spring portion 126 is kept in a non-contact state with the bottom surface 102 a of the guide groove 102.

In this state, the shifter 92 is continuously slid along the speed change shaft 26 in the axial direction as indicated by an arrow A.
Since the second contact surface 131b is in contact with the base 125, the base 125 is maintained in a reinforced state with the second contact surface 131b.
Thereby, the base 125 can be smoothly slid along the speed change shaft 26, and the speed change operation can be performed satisfactorily.

FIGS. 8A and 8B are views for explaining an example of engagement with the second transmission gear and the first transmission gear in the key shift transmission according to the present invention.
In (a), the key protrusion 123 of the key member 94 is engaged with the second engagement groove 88 a of the second transmission gear 88.
The second transmission gear 88 can be rotated integrally with the transmission shaft 26 by engaging the key protrusion 123 with the second engagement groove 88a.

The leaf spring portion 126 is kept in a non-contact state with the bottom surface 102 a of the guide groove 102, and the portion 126 b on the base 125 side is kept away from the arm portion 122.
From this state, the shifter 92 is slid along the transmission shaft 26 in the axial direction as indicated by an arrow C.

In (b), the key protrusion 123 of the key member 94 is engaged with the first engagement groove 87 a of the first transmission gear 87.
The first transmission gear 87 can be rotated integrally with the transmission shaft 26 by engaging the key protrusion 123 with the first engagement groove 87a.
The leaf spring portion 126 is kept in a non-contact state with the bottom surface 102 a of the guide groove 102, and the portion 126 b on the base 125 side is kept away from the arm portion 122.

As described with reference to FIGS. 7 and 8, it is possible to prevent the leaf spring portion 126 from being worn by keeping the leaf spring portion 126 of the spring member 96 in a non-contact state with respect to the bottom surface 102 a of the guide groove 102. , Durability can be ensured.
Furthermore, by preventing wear of the leaf spring portion 126, the spring constant of the leaf spring portion 126 can be kept constant. Thereby, the key projection 123 of the key member 94 can be satisfactorily engaged with the first to third transmission gears 87 to 89, and the gear shifting can be performed accurately.

In the above-described embodiment, the example in which the key shift transmission 15 according to the present invention is applied to the walking lawn mower 10 has been described. However, the present invention is not limited to this, and can be applied to other working machines. .
For example, the present invention can be applied to a walking type mower, a walking type snowplow, a walking type tiller, and a walking type one-wheel / two-wheel / three-wheel / four-wheel transport vehicle with a motor.

  The present invention is suitable for application to a key shift transmission that performs a shift by selecting an arbitrary gear from a plurality of transmission gears and engaging the selected transmission gear with a drive transmission shaft.

It is a perspective view which shows the walk-type lawn mower provided with the key shift type transmission according to the present invention. It is sectional drawing which shows the key shift type transmission which concerns on this invention. 3 is a cross-sectional view taken along line 3-3 of FIG. It is a perspective view which shows the principal part of the key shift type transmission which concerns on this invention. It is a disassembled perspective view which shows the principal part of the key shift type transmission which concerns on this invention. It is a side view which shows the key member and spring member of the key shift type transmission which concerns on this invention. It is a figure explaining the example which shifts from a 3rd transmission gear to a 2nd transmission gear in the key shift type transmission which concerns on this invention. It is a figure explaining the example engaged with the 2nd transmission gear and the 1st transmission gear in the key shift type speed change device concerning the present invention. It is sectional drawing which shows the conventional key shift type transmission.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 15 ... Key shift type transmission, 26 ... Transmission shaft (rear wheel drive shaft), 53 ... Transmission mechanism, 87 ... 1st transmission gear (transmission gear), 88 ... 2nd transmission gear (transmission gear), 89 ... 3rd transmission Gear (transmission gear), 90 ... boss member, 92 ... shifter, 94 ... key member, 96 ... spring member, 102 ... guide groove, 102a ... bottom surface of the guide groove (member on the transmission shaft side), 116 ... storage recess, 121 ... Connecting part, 122 ... Arm part, 122a ... A tip part of the arm part, 123 ... A key protrusion, 125 ... A base part, 126 ... A leaf spring part, 126a ... A tip pressing part of a leaf spring part, 126b ... A site on the base side, 131a ... 1st contact surface, 131b ... 2nd contact surface (contact surface).

Claims (4)

A key-shift transmission that can be shifted by rotating a plurality of transmission gears on a transmission shaft, selecting an arbitrary transmission gear from the plurality of transmission gears, and rotating the selected transmission gear together with the transmission shaft. In
A shifter provided movably along the transmission shaft;
A key member provided with a key projection that is connected to the shifter, an arm portion extends from the connection portion along the speed change shaft, and a front end portion of the arm portion is engageable with the speed change gear;
A base portion is fitted into the connecting portion of the key member, and a leaf spring portion extends from the base portion along the arm portion to the transmission shaft side in a non-contact state. A spring member that presses the portion in a direction to engage the transmission gear;
With
A key shift transmission comprising: a gear shift gear coupled to the speed change shaft by engaging the key protrusion with the speed change gear. The shifter is formed with the storage recess for storing the connecting portion and the base portion,
2. The key shift transmission according to claim 1, wherein the key shift transmission can be directly slid along the transmission shaft. The connecting portion has a contact surface facing the base,
This contact surface is
In the engaged state where the key protrusion is engaged with the transmission gear, the key projection is separated from the base portion toward the transmission gear,
3. The key shift transmission according to claim 1, wherein the key protrusion is formed so as to abut against the base in a shift state in which the key protrusion is retracted from the transmission gear.   The key shift type transmission according to any one of claims 1 to 3, wherein the leaf spring portion has a portion on the base side excluding the tip pressing portion away from the arm portion.

Images