JP2005226506A - Engine with governor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine with a governor capable of simplifying a constitution, capable of reducing the size and weight, and capable of securing smooth valve system operation. <P>SOLUTION: This engine 1 with the governor has the governor 20 rotatably installed in a cylinder block 2 via a support shaft 21 and adjusting an engine speed on the basis of rotation of a governor case 22 synchronously rotating with a crankshaft 6. The engine has a timing belt 15 extended between a driving side timing belt pulley 11 arranged on the crankshaft 6 and a driven side timing belt pulley 13 arranged on a camshaft 8. A pulley 23 is formed on the outer periphery of the governor case 22, and rotatingly drives the governor case 22 by being brought into pressure contact with an outer peripheral surface 18 of the timing belt 15 between both timing belt pulleys 11 and 13, and applies tension to the timing belt 15. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an engine with a governor, and more particularly, with a governor provided with a governor that adjusts the engine speed based on the rotation of a driven wheel that is rotatably mounted on a cylinder block via a support shaft and rotates synchronously with a crankshaft. Related to the engine.

  For example, an OHC (overhead camshaft) type general-purpose engine in which the camshaft of the intake / exhaust valve is arranged at the upper part of the cylinder head has a crankcase 102 integrated with the lower part of the cylinder part 101 as shown in a sectional view in FIG. The cylinder block 100 is formed, and the cylinder head 103 is attached to the cylinder block 100. A crankshaft 104 that is rotatably attached to the crankcase 102 and a piston (not shown) that is reciprocally attached to the cylinder portion 101 are connected to each other via a connecting rod. Driven by rotation.

  The cylinder head 103 is provided with an intake valve that opens and closes an intake port, an exhaust valve that opens and closes an exhaust port, and a spark plug (all not shown). A camshaft 106 having a cam 105 that opens and closes the intake valve is disposed in parallel with the crankshaft 104 and is rotatably provided on the cylinder head 103. A rocker arm that swings in contact with the cam surface of the cam 105 has an intake valve. It is connected to. The opening / closing operation of the exhaust valve is performed by a rocker arm attached to the camshaft 106 out of phase with the cam 105. The cylinder head 103 is detachably mounted with a head cover 103a that covers valve operating mechanisms such as the rocker arms and the camshaft 106.

  The power transmission mechanism for transmitting the rotation of the crankshaft 104 to the camshaft 106 is performed between a driving side timing belt pulley 111 provided on the crankshaft 104 and a driven side timing belt pulley 112 provided on the camshaft 106. A belt 113 is stretched (see, for example, Patent Document 1).

  Further, a governor drive gear 107 is coaxially provided on the crankshaft 104. A centrifugal governor 120 is provided in the crankcase 102 of the cylinder block 100 to adjust the engine speed. The governor 120 is a cylindrical shape that is supported by the crankcase 102 and rotatably supported via a support shaft 121 that is arranged in parallel to the crankshaft 104. The governor 120 is an outer portion that becomes a governor driven gear that meshes with the governor drive gear 107 on the outer periphery. A governor case 122 formed with teeth 123 and rotating synchronously with the crankshaft 104, a fly weight 124 disposed in the governor case 122 and swinging in accordance with the rotation of the governor case 122, and interlocking with the swing of the fly weight 124 A governor sleeve 125 that moves forward and backward in the axial direction, and a tip end of the governor shaft 126 that is rotatably attached to the crankcase 102 abuts on the tip end of the governor sleeve 125, The governor lever 127 attached to the proximal end is rotatably illustrated. It is connected via a throttle lever and Gabanaroddo the vaporizer.

  With this configuration, the governor case 122 is rotationally driven in synchronization with the rotation of the crankshaft 104, and when the engine load fluctuates, the governor sleeve 125 moves by a predetermined amount corresponding to the change in the rotational speed of the crankshaft 104. Depending on the amount of movement, the throttle lever of the carburetor is operated via the governor shaft 126, the governor lever 127, etc., and the engine speed is adjusted. This type of centrifugal governor is disclosed in Patent Document 2.

JP 10-89444 A JP-A-8-338278

  In the general-purpose engine, the governor drive gear 107 disposed on the crankshaft 104 and the external teeth 123 formed on the outer periphery of the governor case 122 are directly meshed with each other, and the crankshaft 104 and the governor case 122 are connected. Synchronously rotating.

  For this reason, the relative position between the crankshaft 104 and the governor case 122 is restricted, the installation position of the governor 120 is restricted, and the degree of freedom in designing the engine is restricted, and the governor drive is provided with the timing belt pulley 111 on the crankshaft 104. Since the gear 107 is arranged, the crankshaft 104 itself becomes long due to the arrangement space, and the size of the cylinder block 100 is increased, particularly the axial direction of the crankshaft 104 is increased, leading to an increase in the size of the engine and an increase in weight. There is a concern that the manufacturing cost may increase due to a large number of components and a complicated structure.

  On the other hand, it is necessary to apply an appropriate tension to the timing belt 113 that is stretched between the driving side timing belt pulley 111 and the driven side timing belt pulley 112 to ensure the smooth operation of the valve mechanism. .

  The same applies to a valve operating mechanism using a chain in which a drive-side sprocket is provided on the crankshaft 104, a driven-side sprocket is provided on the camshaft 106, and the chain is driven between these sprockets and the camshaft is driven by the chain. Is concerned.

  Accordingly, an object of the present invention made in view of such a point is to provide a governor-equipped engine that can be simplified in structure and reduced in size and weight and can ensure smooth valve operation.

  The invention of the engine with a governor according to claim 1, which achieves the above object, is configured to reduce the engine speed based on rotation of a driven wheel which is rotatably mounted on a cylinder block via a support shaft and rotates synchronously with a crankshaft. A governor-equipped engine having a governor to be adjusted includes a timing belt suspended between a driving side timing belt pulley provided on the crankshaft and a driven side timing belt pulley provided on the camshaft. The driving wheel is a pulley that is rotationally driven in pressure contact with the outer peripheral surface of the timing belt between the driving side timing belt pulley and the driven side timing belt pulley.

  According to a second aspect of the present invention, there is provided a governor equipped with a governor that adjusts the engine speed based on rotation of a driven wheel that is rotatably mounted on a cylinder block via a support shaft and rotates synchronously with a crankshaft. Further, the engine with a governor includes a timing belt that is stretched between a driving side timing belt pulley provided on the crankshaft and a driven side timing belt pulley provided on the camshaft, and the driven wheel includes the driving wheel. It is a toothed belt pulley that meshes with external teeth formed on the outer peripheral surface of the timing belt between the driving side timing belt pulley and the driven side timing belt pulley.

  According to a third aspect of the present invention, there is provided a governor equipped with a governor that adjusts the engine speed based on rotation of a driven wheel that is rotatably mounted on a cylinder block via a support shaft and rotates synchronously with a crankshaft. Further, the engine with a governor includes a chain spanned between a driving side sprocket provided on the crankshaft and a driven side sprocket provided on the camshaft, and the driven wheel is driven by the driving side sprocket. It is a sprocket that meshes with the chain with the side sprocket.

  According to a fourth aspect of the present invention, in the engine with a governor according to any one of the first to third aspects, the governor includes a cylindrical governor case rotatably supported by the cylinder block via a support shaft. A flyweight disposed in the governor case and swinging in response to the rotation of the governor case, and a governor sleeve moving forward and backward in the axial direction in conjunction with the swinging of the flyweight. A centrifugal governor that adjusts the engine speed in accordance with forward / backward movement, wherein the driven wheel is formed on an outer periphery of the governor case.

  According to the first aspect of the present invention, the driving side timing belt is provided on the outer peripheral surface of the timing belt that is stretched between the driving side timing belt pulley provided on the crankshaft and the driven side timing belt pulley provided on the camshaft. Since the pulley that drives the governor is pressed between the belt pulley and the driven timing belt pulley and is driven to rotate, the pulley that rotationally drives the governor applies tension to the timing belt to suppress unnecessary vibration and deflection. It also functions as an idler pulley or tension pulley, and it can ensure smooth operation of the valve mechanism by applying appropriate tension to the timing belt without complicating the structure due to the arrangement of idler pulleys and tension pulleys. . In addition, since the governor is driven by pressing the pulley against the outer peripheral surface of the timing belt, the restriction on the governor placement position is relaxed compared to the conventional structure in which the governor placement position is limited by a governor drive gear or the like. Ensuring engine design freedom.

  Furthermore, with the omission of the governor drive gear arranged coaxially with the crankshaft, the simplification of the structure can be obtained, and the arrangement space is not required, and the crankshaft is shortened and the cylinder block is reduced in size and weight. The manufacturing cost can be expected to be reduced.

  According to the invention of claim 2, the outer side formed on the outer peripheral surface of the timing belt stretched between the driving side timing belt pulley provided on the crankshaft and the driven side timing belt pulley provided on the camshaft. Since the toothed belt pulley for driving the governor is meshed with the tooth between the driving side timing belt pulley and the driven side timing belt pulley, the toothed belt pulley is driven to rotate. Can be activated.

  According to the invention of claim 3, between the driving side sprocket and the driven side sprocket, the chain spanned between the driving side sprocket provided on the crankshaft and the driven side sprocket provided on the camshaft. Since the sprocket that drives the governor is rotated and meshed, the sprocket that drives the governor also functions as an idler sprocket or tension sprocket that applies tension to the chain, making the chain without complicating the structure. Appropriate tension can be applied to ensure smooth operation of the valve mechanism. In addition, since the governor is driven by a sprocket that meshes with the chain, the restriction on the governor placement position is relaxed compared to the conventional structure where the governor placement position is limited by the governor drive gear, ensuring engine design flexibility. it can. Further, with the omission of the governor drive gear arranged on the crankshaft, the structure can be simplified, the arrangement space becomes unnecessary, the crankshaft is shortened, and the cylinder block is reduced in size and weight. Reduction of manufacturing cost can be expected.

  The invention of claim 4 shows a specific example of a governor, and a fly that swings in response to the rotation of the governor case in a cylindrical governor case rotatably supported by a cylinder block via a support shaft. A centrifugal type governor that adjusts the engine speed according to the advance / retreat movement of the governor sleeve that moves forward and backward in the axial direction in conjunction with the swing of the flyweight, and has a driven wheel formed on the outer periphery of the governor case. Thus, the existing governor can be easily configured without greatly changing.

  Hereinafter, an embodiment of an engine with a governor according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. 1 is an overall cross-sectional view of a general-purpose engine 1 with a governor showing an outline of the present embodiment, FIG. 2 is an enlarged view of a portion A in FIG. 1, FIG. 3 is a schematic explanatory diagram of a governor 20 of the general-purpose engine 1, and FIG. FIG. 3 is a cross-sectional view taken along line II of FIG.

  As shown in FIGS. 1 to 3, the engine 1 has a cylinder block 2 in which a crankcase 4 is integrally coupled to a lower portion of a cylinder portion 3, and a cylinder head 5 is attached to the cylinder block 2. A crankshaft 6 rotatably attached to the crankcase 4 via a bearing and a piston (not shown) reciprocally arranged to the cylinder portion 3 are connected via a connecting rod, and the crank is moved by the reciprocating motion of the piston. The shaft 6 is rotationally driven.

  The cylinder head 5 is provided with an intake valve that opens and closes an intake port, an exhaust valve that opens and closes an exhaust port, and a spark plug (all not shown). A camshaft 8 having a cam 7 that opens and closes an intake valve is disposed in parallel with the crankshaft 6 and is rotatably provided on the cylinder head 5. The camshaft 8 contacts the cam surface of the cam 7 attached to the camshaft 8. The rocker arm that swings is connected to the intake valve. The opening / closing operation of the exhaust valve is performed by a rocker arm attached to the camshaft 8 out of phase with the cam 7. A head cover 9 that covers valve operating mechanisms such as each rocker arm and camshaft 8 is detachably attached to the cylinder head 5.

  The power transmission mechanism 10 that transmits the rotation of the crankshaft 6 to the camshaft 8 includes a driving side timing belt pulley 11 provided on the crankshaft 6, a driven side timing belt pulley 13 provided on the camshaft 8, and a timing belt. An endless timing belt 15 is provided between the pulley 11 and the timing belt pulley 13.

  The drive-side timing belt pulley 11 has a disk shape and is formed with outer teeth 12 having a substantially rectangular shape at an equal pitch on the outer periphery, and the driven-side timing belt pulley 13 is also formed on the outer periphery with a substantially rectangular outer shape at an equal pitch. Teeth 14 are formed to project. The timing belt 15 has an endless annular shape with substantially rectangular inner teeth 16 projecting at an equal pitch on the inner periphery thereof and an outer peripheral surface 18 formed substantially flat, and is adjacent to the outer teeth 12 of the drive side timing belt pulley 11. The tooth groove 17 between the inner teeth 16 is engaged, and similarly, the tooth groove 17 between the inner teeth 16 is engaged with the outer teeth 14 of the driven timing belt pulley 13, and the driving side timing bell pulley 11 and the driven side are engaged. It is stretched between the timing belt pulleys 13.

  The governor 20 is arranged in parallel with the crankshaft 6 in the crankcase 4 of the cylinder block 2 as shown in FIG. 2, as shown in FIG. 3 as a schematic explanatory diagram, and as shown in FIG. A bottomed cylindrical governor case 22 is rotatably supported coaxially on a support shaft 21 that is attached to the support shaft 21, and a pulley 23 that is a driven wheel is integrally formed on the outer periphery of the tip of the governor case 22. Anti-slip processing such as knurling is applied to the surface of The pulley 23 comes into pressure contact with the outer peripheral surface 18 of the timing belt 15 on the side where the loose side tension acts between the driving side timing belt pulley 11 and the driven side timing belt pulley 13, and the crankshaft 6 is interposed via the timing belt 15. The governor case 22 is rotationally driven in synchronization.

  A flyweight 25 that swings (expands) by centrifugal force accompanying rotation of the governor case 22 is provided in the governor case 22. The base end portion of the flyweight 25 abuts on a governor sleeve 26 that is slidable in the axial direction on the support shaft 21, and the governor sleeve 26 is slid in the axial direction by the centrifugal urging force of the flyweight 25. The tip of the governor sleeve 26 is in contact with a curved tip of a governor shaft 27 that is rotatably mounted on the crankcase 4, and a governor lever 28 that is rotatably fixed to the base end of the governor shaft 27 is a carburetor (not shown). The throttle lever is connected via a governor rod 29 (see FIG. 3).

  A governor spring 30 is stretched between the governor lever 28 and a speed control lever (not shown) to urge the governor lever 28 with an urging force corresponding to the amount of rotation of the governor lever 28, that is, the amount of movement of the governor sleeve 26. This urging force is transmitted to the tip of the governor sleeve 26 via the governor shaft 27 to generate a counter urging force in a direction opposite to the centrifugal urging force.

  With this configuration, when a load change occurs during engine operation, the rotation of the governor case 22 that rotates in synchronization with the crankshaft 6 via the timing belt 15 in response to a change in the rotation speed of the crankshaft 6 caused by this change. The speed changes and the flyweight swing amount (expansion amount) changes due to the centrifugal force change of the flyweight 25, whereby the governor sleeve 26 moves by a predetermined amount, and the governor shaft 27, the governor lever 28, etc. according to this movement amount. The throttle lever of the carburetor is operated via the engine to adjust the engine speed.

  On the other hand, on the outer peripheral surface 18 of the timing belt 15 stretched between the driving side timing belt pulley 11 provided on the crankshaft 6 and the driven side timing belt pulley 13 provided on the camshaft 8, the driving side timing belt is provided. A pulley 23 formed on a governor case 22 rotatably supported by a support shaft 21 fixed to the crankcase 4 is pressed between the pulley 11 and the driven timing belt pulley 13. That is, the pulley 23 is urged so that the timing belt 15 protrudes inward by a predetermined amount between the driving side timing belt pulley 11 and the driven side timing belt pulley 13 of the timing belt 15, and is rotated by being applied with tension. Therefore, the pulley 23 that rotationally drives the governor case 22 functions as an idler pulley or tension pulley that applies tension to the timing belt 15 to suppress unnecessary vibration and deflection, and an idler pulley and a tension pulley are separately arranged. Without being complicated in structure, it is possible to apply an appropriate tension to the timing belt 15 to ensure smooth operation of the valve mechanism.

  Further, since the governor case 22 is rotationally driven by pressing the pulley 23 against the outer peripheral surface 18 of the timing belt 15, the arrangement position is more restricted than the conventional structure in which the arrangement position of the governor 20 is limited by the governor drive gear. Can be relaxed and engine design freedom can be secured.

  Further, with the omission of the governor drive gear arranged coaxially with the crankshaft 6, the structure can be simplified, and the arrangement space for that is not required, and the crankshaft 6 can be shortened and the crankcase 4 can be reduced. The included cylinder block 2 can be reduced in size and weight, and the production cost of the engine 1 can be expected to be reduced. Further, by forming the pulley 23 on the outer periphery of the governor case 22, the present embodiment can be easily configured without greatly changing the existing governor 20.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view of the main part corresponding to FIG. 2 in the first embodiment, and the same reference numerals are given to the parts corresponding to FIG. 1 to FIG.

  In the present embodiment, substantially rectangular external teeth 19 are formed at an equal pitch on the outer peripheral surface 18 of the timing belt 15 in the first embodiment, and a driven wheel is used instead of the pulley 23 on the outer periphery of the tip of the governor case 22. Is constituted by a toothed pulley 41 having teeth 42 meshing with the external teeth 19 formed on the outer peripheral surface 18 of the timing belt 15. Other configurations are the same as those of the first embodiment.

  As a result, the external teeth 19 formed on the outer peripheral surface 18 of the timing belt 15 spanned between the both timing belt pulleys 11 and 13 are toothed on the governor case 22 between the both timing belt pulleys 11 and 13. Since the teeth 42 of the pulley 41 are engaged with each other and the governor case 22 is rotationally driven, the occurrence of slip or the like between the timing belt 15 and the governor case 22 is eliminated, and the engine rotation by the governor 20 is compared with the first embodiment. The speed control reliability of the number can be further improved.

(Third embodiment)
A third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view of the main part corresponding to FIG. 2 in the first embodiment, and the same reference numerals are given to the parts corresponding to FIG. 1 to FIG.

  In the present embodiment, a chain 46 is employed as the power transmission mechanism 10 that transmits the rotation of the crankshaft 6 to the camshaft 8. That is, a drive side sprocket 45 is attached instead of the timing belt pulley 11 attached to the crankshaft 6 in the first embodiment, a driven side sprocket (not shown) is attached to the camshaft 8 instead of the timing belt pulley 13, and both The chain 46 is spanned between the sprockets. On the other hand, instead of the pulley 23 on the outer periphery of the tip of the governor case 22, the driven wheel is constituted by a sprocket 47 having teeth 48 that mesh with the chain 46. Other configurations are the same as those of the first embodiment.

  Thus, the same effect as that of the first embodiment can be ensured also in the engine including the power transmission mechanism 10 by chain drive. That is, the chain 46 spanned between the drive side sprocket 45 and the driven side sprocket is engaged with the sprocket 47 formed in the governor case 22 between the drive side sprocket 45 and the driven side sprocket to be driven to rotate. Therefore, the sprocket 47 formed in the governor case 22 also functions as an idler sprocket or tension sprocket that applies tension to the chain 46, and applies appropriate tension to the chain 46 without complicated structure. Smooth operation of the mechanism can be ensured.

  Further, since the governor 20 is driven by the sprocket 47 meshing with the chain 46, the restriction on the position of the governor 20 is relaxed compared to the conventional structure in which the position of the governor 20 is limited by the governor drive gear. Design freedom can be secured. Further, with the omission of the governor drive gear arranged on the crankshaft 6, the structure can be simplified, and the arrangement space becomes unnecessary, so that the crankshaft 6 can be shortened and the cylinder block 2 can be reduced in size and weight. The manufacturing cost can be expected to be reduced.

1 is an overall cross-sectional view of a general-purpose engine according to a first embodiment of the present invention. Similarly, it is the A section enlarged view of FIG. Similarly, it is a schematic explanatory diagram of the governor. Similarly, it is the II sectional view taken on the line of FIG. It is principal part sectional drawing of a general purpose engine concerning 2nd Embodiment of this invention. It is principal part sectional drawing of a general purpose engine concerning 3rd Embodiment of this invention. It is a whole sectional view showing the outline of the conventional general purpose engine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder block 6 Crankshaft 7 Cam 8 Camshaft 10 Power transmission mechanism 11 Drive side timing belt pulley 13 Driven side timing belt pulley 15 Timing belt 18 Outer surface 20 Governor 21 Support shaft 22 Governor case 23 Pulley (driven wheel)
25 Flyweight 26 Governor sleeve 41 Toothed pulley (driven wheel)
45 Drive side sprocket 46 Chain 47 Sprocket (driven wheel)

Claims (4)

In a governor-equipped engine having a governor that is rotatably mounted on a cylinder block via a support shaft and adjusts the engine speed based on the rotation of a driven wheel that rotates synchronously with a crankshaft,
A timing belt stretched between a driving side timing belt pulley provided on the crankshaft and a driven side timing belt pulley provided on the camshaft;
An engine with a governor, wherein the driven wheel is a pulley that is rotationally driven in pressure contact with an outer peripheral surface of a timing belt between the driving side timing belt pulley and the driven side timing belt pulley. In a governor-equipped engine having a governor that is rotatably mounted on a cylinder block via a support shaft and adjusts the engine speed based on the rotation of a driven wheel that rotates synchronously with a crankshaft,
A timing belt stretched between a driving side timing belt pulley provided on the crankshaft and a driven side timing belt pulley provided on the camshaft;
An engine with a governor, wherein the driven wheel is a toothed belt pulley that meshes with an external tooth formed on an outer peripheral surface of the timing belt between the driving side timing belt pulley and the driven side timing belt pulley. In a governor-equipped engine having a governor that is rotatably mounted on a cylinder block via a support shaft and adjusts the engine speed based on the rotation of a driven wheel that rotates synchronously with a crankshaft,
A chain spanned between a drive side sprocket provided on the crankshaft and a driven side sprocket provided on the camshaft;
The engine with a governor, wherein the driven wheel is a sprocket that meshes with the chain between the driving side sprocket and the driven side sprocket. The governor includes a cylindrical governor case that is rotatably supported by the cylinder block via a support shaft, a flyweight that is disposed in the governor case and swings according to the rotation of the governor case, A governor sleeve that moves forward and backward in the axial direction in conjunction with the swing of the flyweight, and a centrifugal governor that adjusts the engine speed according to the forward and backward movement of the governor sleeve,
The engine with a governor according to any one of claims 1 to 3, wherein the driven wheel is formed on an outer periphery of the governor case.

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