JP6014177B2 - Decompression device for motorcycle and motorcycle equipped with the same - Google Patents

Description

  The present invention relates to a decompression device for a motorcycle and a motorcycle including the same.

  Conventionally, a decompression device for reducing the compression pressure of a combustion chamber is known. For example, Patent Document 1 discloses a decompression device including a camshaft, a decompression cam, a decompression weight, a power transmission member, and a torsion coil spring. The decompression cam is rotatably supported by the cam lobe and acts on the engine valve according to the rotation angle. The decompression weight is pivotally supported on the side surface of the cam lobe and swings due to centrifugal force. The power transmission member transmits the swing of the decompression weight to the decompression cam. The torsion coil spring biases the decompression weight in a direction that resists swinging of the decompression weight due to centrifugal force. In this decompression device, by reducing the spring constant of the torsion coil spring, the engine speed is lowered and the engine speed at which the decompression weight starts to swing from the decompression release position to the decompression position is lowered. The idling speed is also set low to reduce fuel consumption.

  Further, Patent Document 2 discloses a decompression device including a drive unit that rotates a decompression shaft with respect to a valve operating camshaft. This driving means includes a centrifugal weight that is rotatably supported by a sprocket of an exhaust camshaft by a support shaft, and a return spring held by the support shaft.

  According to such a decompression device, when the crankshaft is rotated by a starter motor or the like and the internal combustion engine is started, the centrifugal force is weak when the engine speed is low. The decompression position is maintained. That is, the exhaust valve is kept open. Thereby, the compression pressure of the combustion chamber is reduced, and cranking is facilitated. On the other hand, when the engine speed increases due to the first explosion, the centrifugal force increases. Therefore, the decompression weight swings against the urging force of the spring and is maintained at the decompression release position. That is, the exhaust valve is maintained in a closed state. Thereby, the engine speed increases.

  For example, in a motorcycle equipped with a manual starter such as a kick lever, if the compression pressure in the combustion chamber is high, it is difficult to move the piston to the compression top dead center even if the occupant strongly steps on the kick lever. In order to avoid this, the decompression device maintains the decompression weight at the decompression position, and the exhaust valve is opened before the piston reaches the compression top dead center. However, the first explosion cannot be obtained because the compression pressure of the combustion chamber is reduced by opening the exhaust valve. For this reason, conventionally, in order to be able to obtain the first explosion even when the engine speed is low, a method of weakening the urging force of the spring or increasing the decompression weight has been adopted. It was. If the urging force of the spring is weakened, the decompression weight quickly moves to the decompression release position even if the centrifugal force is small. If the decompression weight is increased, the centrifugal force is increased, so that the decompression weight can easily maintain the decompression release position.

JP 2010-001789 A JP 2006-070831 A

  However, there is a limit to weakening the urging force of the spring as in the prior art. Further, if the decompression weight is increased, the weight of the vehicle is increased.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a decompression device for a motorcycle that can facilitate cranking without increasing the weight of the vehicle, and a motorcycle including the same. Is to provide.

A decompression device for a motorcycle according to the present invention includes a cylinder head, an exhaust camshaft formed in a hollow shape, rotatably supported by the cylinder head, and formed with a cam, and biased in a direction to close an exhaust valve. A valve lifter that moves in a direction to open the exhaust valve in response to a pressing force due to the contact of the cam, a first connection member that is disposed inward of the exhaust camshaft and is formed in an axial shape, A first connecting member and a second connecting member formed in a separate shaft and connected to the first connecting member, and relative to the exhaust camshaft between an initial position and an end position. When the rotational speed of the exhaust camshaft exceeds a threshold value, the decompression shaft is moved forward from the initial position with respect to the exhaust camshaft. Comprising a drive member for rotating the first rotary direction until the end position. The exhaust camshaft intersects the first hole portion drilled in the first direction intersecting the axial direction of the exhaust camshaft, the axial direction of the exhaust camshaft, and viewed in the axial direction of the exhaust camshaft. And a second hole formed in a second direction intersecting the first direction. The decompression shaft is slidably inserted into the first hole portion of the exhaust camshaft and is slidably inserted into the second hole portion of the exhaust camshaft and a decompression pin having an end that can contact the valve lifter. And a decompression release pin having an end that can contact the valve lifter. The decompression shaft is configured to rotate together with the exhaust camshaft when in the initial position and at the end position. The decompression pin and the decompression release pin, when the decompression shaft rotates in the first rotation direction from the initial position to the end point position, the decompression pin slides inward of the first hole and the decompression release. When the pin slides inward of the second hole and the decompression shaft rotates in the second rotation direction opposite to the first rotation direction from the end point position to the initial position, the decompression pin is moved to the first position. The decompression pin is engaged with the decompression shaft so that the decompression release pin slides in a direction projecting from the hole, and the decompression release pin slides in a direction projecting from the second hole. The decompression pin extends from the first hole when the decompression shaft is in the initial position and the rotation angle of the exhaust camshaft is at least a part of the compression stroke of the intake stroke and the compression stroke. The end portion of the protruding decompression pin is disposed at a position where the valve lifter is pressed. The decompression release pin protrudes from the second hole when the decompression shaft is in the initial position and the rotation angle of the exhaust camshaft is a combustion stroke or an exhaust stroke. Is disposed at a position where the end of the valve is pressed by the valve lifter. In the motorcycle decompression device, when the end portion of the decompression release pin is pressed by the valve lifter, the decompression release pin slides inward of the second hole, and the decompression shaft is moved to the initial stage. It is comprised so that it may rotate in the said 1st rotation direction from a position to the said end point position.

According to the motorcycle decompression device according to the present invention, when the decompression shaft is in the initial position and the rotation angle of the exhaust camshaft is at least a part of the compression stroke of the intake stroke and the compression stroke , The valve lifter is pressed by the decompression pin , and the exhaust valve is opened. As a result, the compression pressure in the combustion chamber is reduced, and cranking is facilitated. On the other hand, when the decompression shaft is in the initial position and the rotation angle of the exhaust camshaft is the combustion stroke or the exhaust stroke , the decompression release pin is pressed from the valve lifter. As a result, the decompression shaft rotates from the initial position to the end position, the pressure of the valve lifter by the decompression pin is released, and the exhaust valve is closed. Thereby, a favorable first explosion can be obtained. With such a configuration, in the present invention, it is not necessary to weaken the urging force of the urging member of the centrifugal weight, and it is not necessary to increase the weight of the centrifugal weight. Therefore, it is possible to facilitate cranking while improving the motion performance of the vehicle without increasing the weight of the vehicle. In addition, when the engine speed falls below the idling speed, for example, when the clutch is engaged and the brake is applied, for example, before the corner, the decompression function that operates at that time is quickly performed by the decompression release pin. Can be released. Therefore, the engine stall can be prevented without providing other means for preventing the engine stall (hereinafter referred to as engine stall).

According to one aspect of the present invention, the first connecting member has a first end located toward the second connecting member, and a second end located opposite to the first end, The first end of the first connecting member is provided with a first protrusion protruding in the axial direction of the first connecting member at a position deviated from the axial center of the first connecting member, and on the outer peripheral surface of the decompression release pin. Is formed with a first recess that engages with the first protrusion such that the decompression release pin moves in the axial direction as the first connecting member rotates.

According to the said aspect, a 1st connection member and a decompression release pin can be engaged in the position eccentric from the axial center of the said 1st connection member.

According to an aspect of the present invention, the first convex portion is a columnar member, and the axis of the decompression release pin intersects the axis of the first connecting member, and the first convex portion The axis is deviated from the axis of the first connecting member.

According to the above aspect, when the decompression release pin receives the pressing force from the valve lifter, the pressing force can be greatly applied in the direction in which the first convex portion is rotated. Therefore, when the decompression release pin receives a pressing force from the valve lifter, the first connecting member provided with the first convex portion rotates smoothly. As a result, it is possible to smoothly release the pressure on the valve lifter by the decompression pin .

According to one aspect of the present invention, the second connecting member has a first end located toward the first connecting member, and a second end located opposite to the first end, the second end of the second connecting member, at a position axially and sincerely eccentricity of the second coupling member, a second protrusion is provided protruding in the axial direction of the second connecting member, the outer peripheral surface of the decompression pin, A second recess is formed that engages with the second protrusion so that the decompression pin moves in the axial direction as the second connecting member rotates.

According to the said aspect, a 2nd connection member and a decompression pin can be engaged in the position eccentric from the axial center of the said 2nd connection member.

  According to one aspect of the present invention, the first end of the second connecting member is provided with a link member that extends in the axial direction of the second connecting member and engages with the first end of the first connecting member. ing.

  According to the above aspect, the first connecting member and the second connecting member can be connected with a simple configuration.

  According to one aspect of the present invention, when the rotational speed of the exhaust camshaft is equal to or higher than the threshold value, the driving member is configured to resist the centrifugal weight that rotates in the first rotational direction and the rotation of the centrifugal weight in the first rotational direction. A biasing member that biases the centrifugal weight.

According to the above aspect, the first connecting member can be maintained at the initial position by the biasing member. On the other hand, when the rotational speed of the exhaust camshaft becomes equal to or higher than the threshold value, the centrifugal weight can be rotated in the first rotation direction, and the first connecting member can be rotated to the end point position. Thereby, the pressure against the valve lifter by the decompression pin can be released.

According to an aspect of the present invention, the decompression pin has the decompression shaft in the initial position, and the exhaust camshaft has a rotational angle that is a part of the intake stroke and a rotational angle that is a part of the compression stroke. In this case, the end portion of the decompression pin protruding from the first hole is disposed at a position where the valve lifter is pressed.

According to the above aspect, the valve lifter can be pressed by the decompression pin in the intake stroke. Thereby, the exhaust valve can be opened in the intake stroke.

  According to one aspect of the present invention, a motorcycle includes an engine, a starting device that starts the engine, and the above-described decompression device for a motorcycle.

  According to the above aspect, the decompression device for a motorcycle can be applied to a motorcycle provided with a starting device for starting an engine. Thereby, the compression pressure can be reduced in the intake stroke of the motorcycle. As a result, cranking is facilitated. Therefore, it is possible to reduce the size of the cell motor.

  According to one aspect of the invention, the starter is a manual starter that starts the engine manually.

  According to the above aspect, the decompression device for a motorcycle can be applied to a motorcycle equipped with a manual starter. Thereby, the compression pressure can be reduced in the intake stroke of the motorcycle equipped with the manual starter. As a result, it is possible to reduce the load on the occupant when operating the manual starter. Accordingly, the occupant can easily start the engine by operating the manual starter.

  According to one aspect of the present invention, the manual starter has a kick lever that is operated by the foot of an occupant.

  According to the said aspect, the load with respect to a passenger | crew's leg at the time of operation of a kick lever can be reduced. Thereby, the occupant can easily start the engine by operating the kick lever.

  As described above, according to the present invention, it is possible to provide a decompression device for a motorcycle that can facilitate cranking without increasing the weight of the vehicle and a motorcycle including the same.

It is a perspective view showing a decompression device concerning one embodiment of the present invention. (A) is a front view which shows the decompression apparatus which concerns on one Embodiment of this invention, (b) is a rear view which shows the decompression apparatus which concerns on one Embodiment of this invention. It is a longitudinal section showing a decompression device concerning one embodiment of the present invention. It is a perspective view which shows the structure of the decompression shaft which concerns on one Embodiment of this invention. It is the VV sectional view taken on the line of FIG. It is a cross-sectional view of an exhaust camshaft according to an embodiment of the present invention. It is sectional drawing of the cylinder head which concerns on one Embodiment of this invention. It is explanatory drawing which shows the valve lift curve which concerns on one Embodiment of this invention. 1 is a side view of a motorcycle according to an embodiment of the present invention.

  Hereinafter, a motorcycle decompression device and a motorcycle including the same according to an embodiment of the present invention will be described.

  As shown in FIGS. 1 to 3, the motorcycle decompression device 1 according to the present embodiment includes an exhaust camshaft 2, a decompression shaft 3, a centrifugal governor 4 as a drive member, and a sprocket 5. The exhaust camshaft 2 is formed in a shaft shape. The exhaust camshaft 2 is formed in a hollow shape and has a through hole 2a as shown in FIG. The through hole 2a is formed in a shaft shape. As shown in FIG. 7, the exhaust camshaft 2 is rotatably supported by the cylinder head 10. The decompression shaft 3 is inserted into the through hole 2 a of the exhaust camshaft 2. The decompression shaft 3 is provided so as to be rotatable relative to the exhaust camshaft 2 inside the exhaust camshaft 2. The centrifugal governor 4 is connected to one end of the decompression shaft 3. The sprocket 5 is attached to one end of the exhaust camshaft 2. A timing chain (not shown) is wound around the sprocket 5 so that a rotational force from a crankshaft (not shown) is transmitted to the sprocket 5. The sprocket 5 is rotated by the transmitted rotational force. The exhaust camshaft 2 rotates with the rotation of the sprocket 5.

  A plurality of cams 20 are formed on the exhaust camshaft 2. Each cam 20 is arranged side by side in the axial direction of the exhaust camshaft 2. The cam 20 rotates with the rotation of the exhaust camshaft 2.

  As shown in FIG. 7, a valve lifter 11 is disposed below the exhaust camshaft 2. An exhaust valve 12 is connected to the valve lifter 11. As the exhaust camshaft 2 rotates, the cam 20 of the exhaust camshaft 2 comes into contact with the valve lifter 11 or the cam 20 does not come into contact with the valve lifter 11. When the cam 20 contacts the valve lifter 11, the valve lifter 11 moves downward as the cam 20 rotates. Thereby, the exhaust valve 12 is opened. The valve lifter 11 is urged in a direction to close the exhaust valve 12 by a spring 11b. In this embodiment, when the valve lifter 11 is pressed by the cam 20 of the exhaust shaft 2 due to the rotation of the exhaust shaft 2 and the exhaust valve 12 is opened, the valve lifter 11 is pressed by the decompression pin 32 described in detail later. In some cases, the exhaust valve 12 is opened. The timing at which the valve lifter 11 is pressed by the decompression pin 32 is different from the timing at which the valve lifter 11 is pressed by the cam 20 of the exhaust camshaft 2. That is, the valve lifter 11 is pressed by the decompression pin 32 when the valve lifter 11 is not pressed by the cam 20 of the exhaust camshaft 2. Two exhaust valves 12 may be provided.

  An intake camshaft 13 is rotatably supported on the cylinder head 10. A valve lifter 15 is disposed below the intake camshaft 13. An intake valve 16 is connected to the valve lifter 15. Due to the rotation of the intake camshaft 13, the cam 14 of the intake camshaft 13 comes into contact with the valve lifter 15 or the cam 14 does not contact the valve lifter 15. When the cam 14 contacts the valve lifter 15, the valve lifter 15 moves downward as the cam 14 rotates. As a result, the intake valve 16 is opened.

  As shown in FIG. 2A, the centrifugal governor 4 includes a centrifugal weight 40, a support shaft 41, and an urging member 42. The centrifugal weight 40 is rotatably supported on the sprocket 5 by a support shaft 41. The centrifugal weight 40 includes a main body member 40a, a link member 40b, and an engagement member 40c formed in a substantially arc shape. The support shaft 41 is attached to one end portion 40a1 of the main body member 40a. The link member 40b of the centrifugal weight 40 protrudes from the one end portion 40a1 of the main body member 40a toward the axis of the decompression shaft 3. The engaging member 40c of the centrifugal weight 40 is formed in a shaft shape. The engaging member 40c extends in the axial direction of the decompression shaft 3 from the link member 40b. The engaging member 40 c is engaged with an engaging portion 34 a of a disk member 34 described later of the decompression shaft 3. Thereby, the centrifugal governor 4 and the decompression shaft 3 are connected. When the centrifugal governor 4 rotates as the sprocket 5 rotates, centrifugal force acts on the centrifugal governor 4. The centrifugal force acts in the direction in which the other end portion 40a2 of the main body member 40a rotates clockwise in FIG.

  The urging member 42 of the centrifugal governor 4 can be constituted by, for example, a torsion spring. The urging member 42 is wound around the centrifugal weight 40. One end 42 a of the urging member 42 is engaged with the support shaft 41 of the centrifugal governor 4. The other end 42 b of the urging member 42 is engaged with the sprocket 5. The centrifugal weight 40 rotates in the first rotation direction D1 in the clockwise direction in FIG. The biasing member 42 biases the centrifugal weight 40 against the rotation of the centrifugal weight 40.

  As shown in FIG. 3 and FIG. 4, the decompression shaft 3 is formed in a shaft shape, a connecting member 30 formed in a shaft shape, a connecting member 31 formed in a shaft shape separate from the connecting member 30, and a shaft shape, A decompression pin 32 having a circular cross section and a decompression release pin 33 having an axial shape and a circular cross section are provided. The decompression pin 32 contacts the later-described valve lifter 11 to open the exhaust valve 12. Hereinafter, opening the exhaust valve 12 with the decompression pin 32 may be referred to as “decompression”. The decompression release pin 33 is for releasing the decompression by the decompression pin 32. That is, when the decompression is released by the decompression release pin 33, the exhaust valve 12 is closed. Details will be described later.

  A disk member 34 is provided at one end of the connecting member 30. A disk member 35 is provided at the other end of the connecting member 30. The axis of the disc member 34 and the axis of the disc member 35 are coincident with the axis of the connecting member 30. A disk member 36 is provided at one end of the connecting member 31. A disk member 37 is provided at the other end of the connecting member 31. The axis of the disc member 36 and the axis of the disc member 37 are coincident with the axis of the connecting member 31, respectively. The diameters of the disk members 34 to 37 are larger than the diameter of the connecting member 30 and the diameter of the connecting member 31. The disc members 34 to 37 are arranged at predetermined intervals with respect to the inner peripheral wall 2 b of the exhaust camshaft 2.

  As shown in FIGS. 3 and 4, the connecting member 30 and the connecting member 31 are connected. Specifically, the disk member 36 of the connecting member 31 is provided with a link member 38 formed in an axial shape. The link member 38 is disposed at an eccentric position in the disc member 36. The link member 38 extends in a direction perpendicular to the planar direction of the disk member 36, in other words, in the thickness direction of the disk member 36. The link member 38 extends toward the disc member 35 of the connecting member 30. The disc member 35 is formed with a fitting portion 35a. The fitting portion 35 a is disposed at an eccentric position in the disc member 35. The fitting part 35 a is formed by hollowing out a part of the disk member 35 in the thickness direction of the disk member 35. The fitting portion 35a is formed by being cut out over the entire length of the disc member 35 in the thickness direction. The link member 38 is fitted in the fitting portion 35 a of the disk member 35. Thereby, the connection member 30 and the connection member 31 are connected.

  As described above, the disk member 34 of the connecting member 30 is provided with the engaging portion 34a. As shown in FIG. 4, the engaging portion 34 a is disposed at an eccentric position in the disc member 34. The engaging portion 34 a is formed by hollowing out a part of the disk member 34 in the thickness direction of the disk member 34. The engaging portion 34 a is formed by being cut out from one surface of the disk member 34, that is, the surface of the disk member 34 toward the centrifugal governor 4 over a part of the disk member 34 in the thickness direction. ing. The engaging member 40c (see FIG. 3) of the centrifugal weight 40 is engaged with the engaging portion 34a. Thereby, the centrifugal governor 4 and the decompression shaft 3 are connected.

  A centrifugal weight stopper 34 b is provided on the disk member 34 of the connecting member 30. The centrifugal weight stopper 34 b extends in the thickness direction of the disk member 34 on the one surface of the disk member 34. As shown in FIG. 2A, the portion of the centrifugal weight stopper 34b that contacts the main body member 40a of the centrifugal weight 40 is formed in an arc shape. The centrifugal weight stopper 34b restricts the rotation of the main body member 40a of the centrifugal weight 40 in the urging direction of the urging member 42. The position where the connecting member 30 is rotated to the position where the rotation of the centrifugal weight 40 is restricted by the centrifugal weight stopper 34b corresponds to the initial position.

  Further, as shown in FIG. 2A, a centrifugal weight stopper 5 a is provided on the peripheral portion of the sprocket 5. The centrifugal weight stopper 5a is formed in an arc shape when the exhaust camshaft 2 is viewed in the axial direction. When the rotational speed of the exhaust camshaft 2 becomes equal to or greater than the threshold value, a centrifugal force larger than the biasing force of the biasing member 42 is generated in the centrifugal weight 40. Therefore, the centrifugal weight 40 rotates in the first rotation direction D1 with respect to the exhaust camshaft 2. The centrifugal weight stopper 5a restricts the rotation of the centrifugal weight 40 in the first rotation direction D1. The position where the connecting member 30 is rotated to the position where the rotation of the centrifugal weight 40 is restricted by the centrifugal weight stopper 5a corresponds to the end point position.

  As shown in FIG. 3, the disk member 37 of the connecting member 31 is provided with a convex portion 37 a that protrudes in the axial direction of the connecting member 31. The convex portion 37 a is disposed at a position eccentric on one surface of the disk member 37, that is, on the surface of the disk member 37 opposite to the connection member 31. The convex portion 37a is formed in a cylindrical shape. The decompression pin 32 is provided with a concave portion 32a (see FIG. 4) that fits into the convex portion 37a. The recess 32 a is formed by hollowing out a part of the decompression pin 32 in the length direction of the decompression pin 32. In such a configuration, the decompression pin 32 is connected to the disc member 37 by fitting the convex portion 37 a into the concave portion 32 a. The decompression pin 32 is arranged in a direction crossing the axial direction of the connecting member 30 and the axial direction of the connecting member 31.

  The disk member 35 of the connecting member 30 is provided with a convex portion 35 b that protrudes in the axial direction of the connecting member 30. The convex portion 35 b is arranged at a position eccentric on one surface of the disk member 35, that is, on the surface of the disk member 35 toward the connecting member 31. The convex part 35b is formed in the column shape. The decompression release pin 33 is provided with a concave portion 33a that fits into the convex portion 35b. Similar to the recess 32 a of the decompression pin 32, the recess 33 a is formed by hollowing out a part of the decompression release pin 33 in the length direction of the decompression release pin 33. In such a configuration, the decompression release pin 33 is connected to the disc member 35 by fitting the convex portion 35b into the concave portion 33a. Similar to the decompression pin 32, the decompression release pin 33 is arranged in a direction intersecting the axial direction of the connecting member 30 and the axial direction of the connecting member 31.

  As shown in FIG. 5, the straight line L <b> 1 that intersects the axis of the convex portion 35 b is shifted from the axis L <b> 2 of the decompression release pin 33. In other words, the straight line L1 and the axis L2 do not overlap. As shown in FIG. 6, a straight line L3 that intersects the axis of the convex portion 37a overlaps the axis L4 of the decompression pin 32.

  As shown in FIG. 3, holes 21 to 24 are formed in the exhaust camshaft 2. The holes 21 and 22 (see FIG. 6) are formed in a first direction perpendicular to the axial direction of the exhaust camshaft 2. The holes 23 and 24 are formed in a direction perpendicular to the axial direction of the exhaust camshaft 2 and at a position different from the position where the holes 21 and 22 in the axial direction are formed. In other words, the holes 23 and 24 are formed in a second direction that intersects the first direction as viewed in the axial direction of the exhaust camshaft 2. The decompression pin 32 is slidably inserted into the holes 21 and 22. The decompression release pin 33 is slidably inserted into the holes 23 and 24.

  As shown in FIG. 3, the decompression pin 32 contacts the upper surface 11 a (see FIG. 7) of the valve lifter 11 through the holes 21 and 22. The decompression release pin 33 contacts the upper surface 11 a of the valve lifter 11 through the holes 23 and 24. The decompression pin 32 includes a spherical portion 32b (see FIG. 6) formed in a spherical shape at the lower end thereof. The decompression release pin 33 includes a spherical portion 33b formed in a spherical shape at the lower end thereof. Since the lower end of the decompression pin 32 is formed into a spherical shape and the lower end of the decompression release pin 33 is formed into a spherical shape, the frictional resistance when the spherical portion 32b and the spherical portion 33b contact the upper surface 11a of the valve lifter 11 is reduced. The The length of the upper surface 11 a of the valve lifter 11 in the axial direction of the exhaust camshaft 2 is at least longer than the distance between the spherical portion 32 b of the decompression pin 32 and the spherical portion 33 b of the decompression release pin 33. Accordingly, the decompression pin 32 can be brought into contact with the upper surface 11 a of the valve lifter 11 and the decompression release pin 33 can be brought into contact with the upper surface 11 a of the valve lifter 11 according to the rotation angle of the decompression shaft 3.

  Next, the case where the decompression pin 32 contacts the valve lifter 11 and the case where the decompression release pin 33 contacts the valve lifter 11 will be described.

When the position of the connecting member 30 with respect to the exhaust camshaft 2 is the above-described initial position, the decompression pin 32 is in the first state protruding from the hole 22 (see FIG. 6). When the rotational angle of the exhaust camshaft 2 becomes the first rotation angle, specifically, when it is the rotation angle in the intake stroke or compression stroke, the valve lifter 11 is pressed by the decompression pin 32. As a result, the exhaust valve 12 is opened. On the other hand, when the position of the connecting member 30 with respect to the exhaust camshaft 2 changes from the initial position to the end point position described above, the decompression pin 32 moves inward of the hole portion 22 and enters the second state. Thereby, the pressing of the valve lifter 11 by the decompression pin 32 is released. As a result, the exhaust valve 12 is closed. Thus, the connecting member 30 and the decompression pin 32 are connected so as to execute the first state and the second state.

As described above, the centrifugal weight 40 of the centrifugal governor 4 rotates in conjunction with the rotation of the exhaust camshaft 2. When the rotational speed of the exhaust camshaft 2 becomes equal to or greater than the threshold value, a centrifugal force larger than the urging force of the urging member 42 is generated in the centrifugal weight 40. Therefore, the centrifugal weight 40 rotates in the first rotation direction D1 (see FIG. 2A). Thereby, the rotational position of the connecting member 30 of the exhaust camshaft 2 becomes the above-mentioned end point position. Further, even when the rotation speed of the exhaust camshaft 2 is not equal to or greater than the threshold value, when the rotation angle of the exhaust camshaft 2 becomes the second rotation angle, specifically, when the rotation angle in the combustion stroke is reached, The decompression release pin 33 receives the pressing force from the valve lifter 11 and moves inward of the hole 24. Thereby, the connection member 31 receives a force from the decompression release pin 33 and rotates in the first rotation direction D1 to be in the third state. Thus, the connection member 31 and the decompression release pin 33 are connected so as to execute the third state.

As described above, as a result of the connecting member 31 being in the third state , the decompression pin 32 is moved inward of the hole portion 22 to be in the fourth state. Thereby, the pressing of the valve lifter 11 by the decompression pin 32 is released. That is, decompression is released. As a result, the exhaust valve 12 is closed. Thus, the connecting member 31 and the decompression pin 32 are connected so as to execute the fourth state.

When the connection member 31 rotates in the second rotation direction D2, the connection member 30 also rotates in the second rotation direction D2 along with this. Therefore, the decompression release pin 33 moves from the end point position to the initial position and enters the fifth state. Thus, the connection member 30 and the decompression release pin 33 are connected so as to execute the fifth state.

  When the rotational speed of the exhaust camshaft 2 is lower than the threshold value, the centrifugal weight 40 is maintained at the initial position shown in FIG. 2A, that is, the position when the engine is stopped, by the biasing force of the biasing member 42. The In this case, the rotation of the centrifugal weight 40 is restricted by the centrifugal weight stopper 34b. On the other hand, when the rotational speed of the exhaust camshaft 2 rises and exceeds the above threshold, the centrifugal force applied to the centrifugal weight 40 increases. Therefore, the centrifugal weight 40 rotates in the first rotation direction D1 against the urging force of the urging member 42. As a result, the disc member 34 engaged with the engaging member 40 c of the centrifugal weight 40 rotates in the same direction as the centrifugal weight 40 rotates. Therefore, the decompression shaft 3 rotates. Accordingly, the decompression pin 32 moves inward of the hole 22 of the exhaust camshaft 2. As a result, the pressure on the valve lifter 11 by the decompression pin 32 is released. As a result, the exhaust valve 12 connected to the valve lifter 11 is closed.

When the connecting member 30 is in the initial position, the valve lifter 11 is pressed by the decompression pin 32 in the compression stroke. Therefore, the exhaust valve 12 is opened. As a result, the compression pressure in the combustion chamber is reduced. Thus, for example, in a motorcycle in which the occupant starts the engine 63 by operating a kick lever 67 (to be described later) (hereinafter simply referred to as kick start), the load on the occupant's kick is reduced and the engine can be started easily. Become. However, if the occupant's kicking force is weak, the engine speed does not reach the speed at which decompression can be released, making it difficult to start the engine. Therefore, in the present embodiment, the following is performed to make it easier for the occupant to start the engine.

  The horizontal axis in FIG. 8 indicates the crank angle θ, and the vertical axis indicates the lift amount LD of the intake valve 16 or the exhaust valve 12. As shown in FIG. 8, the lift curve 16 </ b> L shows a change in the lift amount of the intake valve 16 by the cam 14 of the intake camshaft 13. A lift curve 12L indicates a change in the lift amount of the exhaust valve 12 by the cam 20 of the exhaust camshaft 2. The lift straight line 32 </ b> L indicates a change in the lift amount by which the exhaust valve 12 is pressed by the decompression by the decompression pin 32. The lift straight line 33L indicates a change in the displacement amount of the exhaust valve 12 when the decompression is released by the decompression release pin 33, in other words, when the pressure on the valve lifter 11 by the decompression pin 32 is released. According to the lift straight line 32L and the lift straight line 33L, the maximum displacement amount of the exhaust valve 12 is the maximum value F at the bottom dead center BDC.

  As shown in the figure, when the crank angle θ is in a stroke including at least a part of the intake stroke R1 and at least a part of the compression stroke R2, that is, at a rotation angle within the first range θ1, the decompression pin 32 Decompression is executed. Thereby, the valve lifter 11 can be pressed by the decompression pin 32. Thereby, the exhaust valve 12 can be opened. As a result, the compression pressure can be reduced. Therefore, it becomes easy to perform cranking. On the other hand, when the crank angle is in a stroke including at least a part of the combustion stroke R3 and at least a part of the exhaust stroke R4, that is, at a rotation angle within the second range θ2, the decompression release by the decompression release pin 33 is executed. Is done. As a result, the pressure on the valve lifter 11 by the decompression pin 32 is released. Thereby, the exhaust valve 12 can be closed. As a result, the compression pressure can be increased. Therefore, the first explosion can be sufficiently realized.

  Next, an example of the configuration of a motorcycle to which the motorcycle decompression device 1 of the present embodiment is applied will be described. As shown in FIG. 9, the motorcycle 50 includes a head pipe 51. A main frame 52 is disposed behind the head pipe 51. The main frame 52 has an upper frame portion 52a extending rearward from above and a lower frame portion 52b extending downward. The upper frame portion 53a and the lower frame portion 53b of the rear frame 53 are connected to the center portion and the rear portion of the upper frame portion 52a, respectively. The head pipe 51, the main frame 52, and the rear frame 53 constitute a vehicle body frame.

  A pivot shaft (not shown) is provided at the rear of the upper frame portion 52a of the main frame 52. The pivot shaft supports the front end portion of the rear arm 54 so as to swing up and down. A rear wheel 55 is rotatably attached to the rear end portion of the rear arm 54. A fuel tank 56 is disposed on the upper frame portion 52a of the main frame 52. A seat 57 is disposed behind the fuel tank 56.

  Below the head pipe 51, a pair of front forks 58 having a suspension for absorbing an impact in the vertical direction of the vehicle is disposed. A front wheel 59 is rotatably attached to the lower ends of the pair of front forks 58. A front fender 60 is disposed above the front wheel 59. A number plate 61 covering the front of the head pipe 51 is provided in front of the head pipe 51. A handle 62 is rotatably provided above the head pipe 51.

  An engine 63 is attached below the upper frame portion 52 a of the main frame 52. The engine 63 is a four-cycle engine. The decompression device 1 for a motorcycle is disposed inside the engine 63. An exhaust pipe 64 is attached to the front portion of the engine 63. The exhaust pipe 64 is directed rearward and connected to the muffler 65. An intake pipe 66 is attached to the rear part of the engine 63. A kick lever 67 for starting the engine 63 with a user's foot is attached to the rear portion of the engine 63. The kick lever 67 is rotated downward by a passenger's foot when starting the engine 63, thereby driving a power generation device (not shown).

As described above , according to the decompression device 1 for a motorcycle according to the present embodiment, when the rotation angle of the exhaust camshaft 2 reaches the first rotation angle, the valve lifter 11 is pressed by the decompression pin 32, and the exhaust valve 12 Becomes open. As a result, the compression pressure in the combustion chamber is reduced, and cranking is facilitated. On the other hand, when the rotation angle of the exhaust camshaft 2 becomes the second rotation angle, the state where the decompression pin 32 can press the valve lifter 11 is released . Thereby, a favorable first explosion can be obtained. With such a configuration, it is not necessary to weaken the urging force of the urging member 42 of the centrifugal weight 40, and it is not necessary to increase the weight of the centrifugal weight 40 itself. For this reason, it is possible to prevent the weight of the vehicle from being increased by increasing the weight of the centrifugal weight 40. Therefore, cranking can be facilitated while improving the motion performance of the vehicle. Further, when the engine speed is lower than the idling speed, for example, when the clutch is in a connected state and the brake is applied in front of a corner, the decompression function is applied to the decompression pin 33. It can be released quickly. Therefore, it is possible to prevent the engine stall from occurring without providing other means for preventing engine stall.

  According to the motorcycle decompression device 1 of the present embodiment, the straight line L <b> 1 that intersects the axis of the convex portion 35 b of the disc member 35 is offset from the axis L <b> 2 of the decompression release pin 33. In other words, the straight line L1 and the axis L2 do not overlap. Therefore, when the decompression release pin 33 receives a pressing force from the valve lifter 11, the pressing force can be largely applied in the direction in which the convex portion 35b is rotated. Therefore, when the decompression release pin 33 receives a pressing force from the valve lifter 11, the connecting member 30 rotates smoothly. As a result, it is possible to smoothly release the pressure applied to the valve lifter 11 by the decompression pin 32.

  According to the motorcycle decompression device 1 of the present embodiment, the connecting member 30 and the decompression release pin 33 are such that when the joining member 30 rotates in the second rotational direction D2, the decompression release pin 33 moves from the end position to the initial position. It connects so that it may rotate in the 2nd rotation direction D2. Thereby, with the rotation of the connecting member 30 in the second rotation direction D2, the decompression release pin 33 can also be rotated in the second rotation direction D2 from the end point position to the initial position.

  According to the motorcycle decompression device 1 of the present embodiment, the disc member 35 of the connecting member 30 has the convex portion 35 b protruding in the axial direction of the connecting member 30 at a position eccentric from the axial center of the connecting member 30. A recess 33 a is formed on the outer peripheral surface of the decompression release pin 33 and engages with the projection 35 b so that the decompression release pin 33 moves in the axial direction as the connecting member 30 rotates. Thereby, the connecting member 30 and the decompression release pin 33 can be engaged at a position eccentric from the axis of the connecting member 30.

  According to the motorcycle decompression device 1 of the present embodiment, the disc member 37 of the connecting member 31 has the convex portion 37 a that protrudes in the axial direction of the connecting member 31 at a position that is eccentric from the axial center of the connecting member 31. A recess 32 a that is provided on the outer peripheral surface of the decompression pin 32 and that engages with the projection 37 a is formed so that the decompression pin 32 moves in the axial direction as the connecting member 31 rotates. Thereby, the connecting member 31 and the decompression pin 32 can be engaged at a position deviated from the axis of the connecting member 31.

  According to the motorcycle decompression device 1 of the present embodiment, the link member 38 that extends in the axial direction of the connection member 31 and engages with the disk member 35 of the connection member 30 on the disk member 36 of the connection member 31. Is provided. Thereby, the connection member 30 and the connection member 31 can be connected with a simple configuration.

  According to the motorcycle decompression device 1 of the present embodiment, the centrifugal governor 4 as a drive member biases the centrifugal weight 40 against the rotation of the centrifugal weight 40 and the centrifugal weight 40 in the first rotation direction D1. The biasing member 42 is provided. Thereby, the connecting member 30 can be maintained at the initial position by the biasing member 42. On the other hand, when the rotation speed of the exhaust camshaft 2 becomes equal to or higher than the threshold value, the centrifugal weight 40 can be rotated in the first rotation direction D1 to rotate the connecting member 30 to the end point position. Thereby, the pressure against the valve lifter 11 by the decompression pin 32 can be released.

  According to the motorcycle decompression device 1 of the present embodiment, the first rotation angle is the rotation angle of the exhaust camshaft 2 during the intake stroke and the compression stroke, and the second rotation angle is the exhaust cam during the combustion stroke. This is the rotation angle of the shaft 2. Thereby, the valve lifter 11 can be pressed by the decompression pin 32 in the intake stroke and the compression stroke. Thereby, the exhaust valve 12 can be opened in the intake stroke and the compression stroke. In the combustion stroke, the operation of the decompression release pin 33 can release the pressure applied to the valve lifter 11 by the decompression pin 32. Thereby, the exhaust valve 12 can be closed in the combustion stroke.

  According to the motorcycle 50 of the present embodiment, the kick lever 67 for manually starting the engine 63 is provided. By applying the motorcycle decompression device 1 of this embodiment to such a motorcycle 50, the compression pressure can be reduced in the intake stroke and the compression stroke. As a result, the load on the occupant's foot when the kick lever 67 is operated can be reduced. Therefore, the occupant can easily start the engine 63 by operating the kick lever 67.

  In the above embodiment, the centrifugal weight 40, the decompression release pin 33, and the decompression pin 32 are arranged in this order in the axial direction of the exhaust camshaft 2, but the present invention is not limited to this. In the axial direction of the exhaust camshaft 2, the centrifugal weight 40, the decompression pin 32, and the decompression release pin 33 may be disposed in this order. In this case, the connection structure between the connection member 30 and the decompression pin 32 is the same as the connection structure between the connection member 30 and the decompression release pin 33 in FIG. The connection structure between the connection member 31 and the decompression release pin 33 is the same as the connection structure between the connection member 31 and the decompression pin 32 in FIG. However, it is preferable to employ the configuration of FIG. 3 in which the decompression release pin 33 is disposed at a position closer to the centrifugal weight 40 than the decompression pin 32. When the decompression release pin 33 is disposed closer to the centrifugal weight 40, the decompression release pin 33 is located on the inner peripheral wall 2b of the exhaust camshaft 2 than when disposed at a position far from the centrifugal weight 40 (the position of the decompression pin 32 in FIG. 3). This is because it is difficult to be affected by the friction of the decompression shaft 3. Thereby, quick decompression cancellation can be executed.

  In the above embodiment, the disk members 34 and 35 are provided on the connecting member 30, and the disk members 36 and 37 are provided on the connecting member 31. However, it is not limited to this. The connecting member 30 may be formed of a cylindrical member having the same diameter as the disk members 34 and 35, and the connecting member 31 may be formed of a cylindrical member having the same diameter as the disk members 36 and 37. . However, from the viewpoint of weight reduction, it is preferable to employ the configuration of FIG. 3 in which the disk members 34 and 35 are provided on the connecting member 30 and the disk members 36 and 37 are provided on the connecting member 31.

  In the said embodiment, the connection member 30 and the decompression release pin 33 were connected by engaging the convex part 35b and the recessed part 33a. Moreover, the connection member 31 and the decompression pin 32 were connected by engaging the convex part 37a and the recessed part 32a. However, it is not limited to this. For example, the connecting member 30 and the decompression release pin 33 may be connected by connecting the disk member 35 and the decompression release pin 33 with a bolt, for example. Moreover, you may connect the connection member 31 and the decompression pin 32 by connecting the disc member 37 and the decompression pin 32 with a volt | bolt, for example.

  In the above embodiment, a manual starter such as the kick lever 67 is employed as the starter. However, it is not limited to this. A cell motor may be employed as the starting device.

  The terms and expressions used herein are used for explanation and are not used for limited interpretation. It should be recognized that any equivalents of the features shown and described herein are not excluded and that various modifications within the claimed scope of the invention are permitted. The present invention can be embodied in many different forms. This disclosure should be regarded as providing embodiments of the principles of the invention. The embodiments are described herein with the understanding that the embodiments are not intended to limit the invention to the preferred embodiments described and / or illustrated herein. It is not limited to the embodiment described here. The present invention also encompasses any embodiment that includes equivalent elements, modifications, deletions, combinations, improvements and / or changes that may be recognized by those skilled in the art based on this disclosure. Claim limitations should be construed broadly based on the terms used in the claims and should not be limited to the embodiments described herein or in the process of this application.

1 Decompression device for motorcycle 2 Exhaust camshaft 3 Decompression shaft 4 Centrifugal governor (drive member)
10 Cylinder Head 11 Valve Lifter 12 Exhaust Valve 22 Hole (First Hole)
24 hole (second hole)
30 connecting member (first connecting member)
31 connecting member (second connecting member)
32 Decompression pin (1st pin)
32a recess (second recess)
33 Decompression release pin (second pin)
33a recess (first recess)
34, 37 Disc member (second end)
35, 36 Disc member (first end)
35b Convex part (first convex part)
37a Convex part (second convex part)
38 Link member 40 Centrifugal weight 42 Biasing member 50 Motorcycle 63 Engine 67 Kick lever (manual starter)
D1 First rotation direction D2 Second rotation direction L1 Straight line intersecting the axis of the first convex portion L2 Decompression release pin axis R1 Intake stroke R2 Compression stroke R3 Combustion stroke R4 Exhaust stroke θ1 First range rotation angle θ2 Second Range rotation angle

Claims (10)

A cylinder head;
An exhaust camshaft formed in a hollow shape, rotatably supported by the cylinder head, and formed with a cam;
A valve lifter that is biased in a direction to close the exhaust valve and moves in a direction to open the exhaust valve in response to a pressing force due to the contact of the cam;
A first connection member disposed inward of the exhaust camshaft and formed in a shaft shape, and a second connection formed in a shaft shape separate from the first connection member and connected to the first connection member A decompression shaft rotatable relative to the exhaust camshaft between an initial position and an end position ;
Coupled to the first coupling member, the exhaust when the rotational speed of the camshaft becomes equal to or higher than the threshold, the drive for rotating the decompression shaft in a first rotational direction until the end position from the initial position relative to the exhaust camshaft A member, and
The exhaust camshaft intersects the first hole portion drilled in the first direction intersecting the axial direction of the exhaust camshaft, the axial direction of the exhaust camshaft, and viewed in the axial direction of the exhaust camshaft. A second hole bored in a second direction intersecting the first direction,
The decompression shaft is slidably inserted into the first hole portion of the exhaust camshaft and is slidably inserted into the second hole portion of the exhaust camshaft and a decompression pin having an end that can contact the valve lifter. And a decompression release pin having an end that can contact the valve lifter ,
The decompression shaft is configured to rotate with the exhaust camshaft when in the initial position and at the end position;
The decompression pin and the decompression release pin, when the decompression shaft rotates in the first rotation direction from the initial position to the end point position, the decompression pin slides inward of the first hole and the decompression release. When the pin slides inward of the second hole and the decompression shaft rotates in the second rotation direction opposite to the first rotation direction from the end point position to the initial position, the decompression pin is moved to the first position. The decompression pin is engaged with the decompression shaft so that it slides in a direction protruding from the hole and the decompression release pin slides in a direction protruding from the second hole,
The decompression pin extends from the first hole when the decompression shaft is in the initial position and the rotation angle of the exhaust camshaft is at least a part of the compression stroke of the intake stroke and the compression stroke. The end portion of the protruding decompression pin is disposed at a position where the valve lifter is pressed,
The decompression release pin protrudes from the second hole when the decompression shaft is in the initial position and the rotation angle of the exhaust camshaft is a combustion stroke or an exhaust stroke. Is disposed at a position where the end of the valve is pressed against the valve lifter,
When the end portion of the decompression release pin is pressed by the valve lifter, the decompression release pin slides inward of the second hole, and the decompression shaft moves from the initial position to the end position. A decompression device for a motorcycle configured to rotate in one rotation direction . The first connecting member has a first end located toward the second connecting member, and a second end located opposite to the first end,
The first end of the first connecting member is provided with a first convex portion protruding in the axial direction of the first connecting member at a position eccentric from the axis of the first connecting member,
Wherein the outer peripheral surface of the decompression release pin, a first recess for engaging the first projection so that the decompression release pin with the rotation of the first coupling member moves in the axial direction are formed, The decompression device for a motorcycle according to claim 1. The first convex portion is a cylindrical member,
The axis of the decompression release pin intersects the axis of the first connecting member,
The decompression device for a motorcycle according to claim 2 , wherein an axis of the first convex portion is deviated from an axis of the first connecting member . The second connecting member has a first end located toward the first connecting member, and a second end located opposite to the first end,
The second end of the second connecting member is provided with a second convex portion protruding in the axial direction of the second connecting member at a position eccentric from the axis of the second connecting member,
Wherein the outer peripheral surface of the decompression pin, a second recess in which the decompression pin with the rotation of the second connecting member is engaged with the second protrusion to move in the axial direction are formed, in claim 1 The decompression device for motorcycles as described. The first end portion of the second connecting member is provided with a link member that extends in the axial direction of the second connecting member and is engaged with the first end portion of the first connecting member. Item 5. A decompression device for a motorcycle according to item 4 .   When the rotational speed of the exhaust camshaft exceeds a threshold value, the driving member attaches the centrifugal weight that rotates in the first rotational direction and the centrifugal weight against the rotation of the centrifugal weight in the first rotational direction. The decompression device for a motorcycle according to claim 1, comprising a biasing member that biases. The decompression pin has the first hole portion when the decompression shaft is in the initial position and the rotation angle of the exhaust camshaft is a partial rotation angle of the intake stroke and a partial rotation angle of the compression stroke. 2. The decompression device for a motorcycle according to claim 1, wherein the end portion of the decompression pin that protrudes from the rear end is disposed at a position that presses the valve lifter . Engine,
A starting device for starting the engine;
A motorcycle comprising: the decompression device for a motorcycle according to any one of claims 1 to 7 . The motorcycle according to claim 8 , wherein the starter is a manual starter that starts the engine manually. The motorcycle according to claim 9 , wherein the manual starter includes a kick lever operated by a passenger's foot.

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