JP2005226509A - Engine with governor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine with a governor capable of simplifying a constitution, and capable of reducing the size and weight. <P>SOLUTION: This engine 1 has a governor case 22 rotatably journaled to a cylinder block 2 via a support shaft 13, a flyweight 25 arranged in the governor case 22 and rocking in response to rotation of the governor case 22, and a governor sleeve 26 for advancing and retreating by interlocking with rocking of the flyweight 25; and has the governor 20 for adjusting an engine speed in response to the advancing-retreating movement of the governor sleeve 26; and has a gear train 10 for synchronously rotating a cam drive gear 11 arranged on a crankshaft 6 and a cam driven gear 12 arranged on a camshaft 8 by interposing a first idler gear 14 and a second idler gear 17. The first idler gear 14 is integrally formed on the outer periphery of the governor case 22. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an engine with a governor provided with a governor for adjusting the engine speed.

  An OHC (overhead camshaft) type general-purpose engine in which the camshaft of the intake / exhaust valve is arranged at the top of the cylinder head has a cylinder block in which a cylinder part and a crankcase are integrally formed, and the cylinder head is attached to the cylinder block. ing. A crankshaft that is rotatably attached to the crankcase and a piston that is reciprocally connected to the cylinder portion are connected via a connecting rod, and the crankshaft is rotationally driven by the reciprocating motion of the piston. The cylinder head is provided with a camshaft that rotates and opens and closes an intake port and an exhaust port, and a camshaft that opens and closes the exhaust valve. A drive-side timing belt pulley provided on the crankshaft and a follower provided on the camshaft. There is known one in which a camshaft is driven to rotate by rotation of a crankshaft via a timing belt suspended between the side timing belt pulley (see, for example, Patent Document 1).

  However, due to the long-term use or overload of the engine, the timing belt stretched between the driving side timing belt pulley and the driven side timing belt pulley may be extended. If the timing belt is extended, a deviation occurs in the opening / closing timing of the intake valve or the exhaust valve.

  As a countermeasure, it is known that the rotation of the crankshaft is transmitted to the camshaft by a gear train to suppress a deviation in the opening / closing timing of the intake valve and the exhaust valve.

  An OHC type general-purpose engine in which the camshaft is rotationally driven by this gear train has a cylinder block 101 in which a cylinder portion 102 and a crankcase 103 are integrally formed, as shown in FIG. A cylinder head 104 is attached. A crankshaft 105 rotatably attached to the crankcase 103 and a piston (not shown) disposed in a freely reciprocating manner are connected to a cylinder bore of the cylinder portion 102 via a connecting rod. Driven by rotation.

  The cylinder head 104 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 107 having a cam 106 for opening and closing the intake valve is rotatably provided on the cylinder head 104, and a rocker arm that swings in contact with the cam surface of the cam 106 is connected to the intake valve. The opening / closing operation of the exhaust valve is performed by a rocker arm that swings in contact with the cam surface of the cam attached to the camshaft 107 out of phase with the cam 106. The cylinder head 104 is detachably attached with a head cover 104a that covers valve operating mechanisms such as the rocker arms and the camshaft 107.

  The gear train 110 that transmits the rotation of the crankshaft 105 to the camshaft 107 transmits power between the driving cam drive gear 111 provided on the crankshaft 105 and the driven cam driven gear 112 provided on the camshaft 107. It is configured by interposing idler gears 115 and 116 that mesh with each other.

  Further, a governor drive gear 119 is coaxially provided on the crankshaft 105, and a centrifugal governor 120 for adjusting the engine speed is provided in the crankcase 103 of the cylinder block 101. The governor 120 includes a governor case 122 having a cylindrical shape rotatably supported by a support shaft 121 provided in the crankcase 103 and having a governor driven gear 123 that meshes with the governor drive gear 119 on the outer periphery. A flyweight 124 that is arranged and swings according to the rotation of the governor case 122 and a governor sleeve 125 that moves forward and backward in the axial direction in conjunction with the swing of the flyweight 124. A tip of a governor shaft 126 rotatably attached to the case 103 abuts, and a governor lever 127 attached to the base end of the governor shaft 126 is connected to a carburetor (not shown) via a throttle lever and a governor rod.

  With this configuration, the governor case 122 is rotationally driven in synchronism with the rotation of the crankshaft 105, and the governor sleeve 125 moves by a predetermined amount corresponding to a change in the rotational speed of the crankshaft 105 due to a change in engine load. 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 above-described general-purpose engine, the governor drive gear 119 is arranged along with the camshaft gear 111 on the crankshaft 105. Therefore, the crankshaft 105 becomes long due to the arrangement space, and the cylinder block 101 is enlarged. The increase in the axial direction of the crankshaft 105 causes an increase in the size of the engine, resulting in an increase in weight, and there are concerns that an increase in manufacturing cost due to a large number of components and a complicated structure.

  Accordingly, an object of the present invention made in view of such a point is to provide an engine with a governor that can be simplified in configuration and reduced in size and weight.

  The governor-equipped engine according to claim 1, which achieves the above object, adjusts the engine speed based on rotation of a rotating member that is rotatably mounted on a cylinder block via a support shaft and rotates synchronously with a crankshaft. A governor, a cam drive gear provided on the crankshaft, and a cam train gear provided on the camshaft rotate synchronously with an idler gear interposed therebetween, and the idler gear is integrally formed with the rotating member. It is characterized by.

  The governor-equipped engine according to claim 2, which achieves the above object, includes a cylindrical governor case rotatably supported by a cylinder block via a support shaft, and the governor case disposed in the governor case. And a governor sleeve that moves forward and backward in the axial direction of the support shaft in conjunction with the swing of the flyweight, and adjusts the engine speed according to the forward and backward movement of the governor sleeve. And a gear train in which a cam drive gear provided on the crankshaft and a cam driven gear provided on the camshaft rotate synchronously via an idler gear, and the idler gear is integrally formed on the outer periphery of the governor case. It is characterized by that.

  According to the first aspect of the present invention, the idler gear of the gear train is integrally formed with the rotating member of the governor that is rotatably attached to the cylinder block via the support shaft, so that the rotating member of the governor has the function of the idler gear. The member is directly driven to rotate by a cam drive gear provided on the crankshaft. Therefore, it is possible to omit the governor drive gear that has been conventionally arranged coaxially with the crankshaft, thereby reducing the number of components and simplifying the structure, and eliminating the need for space for the governor drive gear. Can be shortened and the cylinder block can be reduced in size and weight, and a reduction in manufacturing cost can be expected.

  According to the invention of claim 2, the idler gear of the gear train is integrally formed on the outer periphery of the governor case rotatably mounted on the cylinder block via the support shaft, so that the governor case has the function of the idler gear. The cam drive gear is directly driven to rotate in synchronization with the crankshaft. Therefore, it is possible to omit the governor drive gear that has been arranged coaxially with the conventional crankshaft, to reduce the number of components and to simplify the structure, and to eliminate the space for arranging the governor drive gear. It is possible to reduce the manufacturing cost while shortening the size and weight of the cylinder block.

  Embodiments of an engine with a governor according to the present invention will be described below 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 of FIG. 1, FIG. 3 is an explanatory diagram of the outline of the governor, and FIG. It is line sectional drawing.

  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. Then, a crankshaft 6 rotatably supported by a crankcase 4 via a bearing and a piston (not shown) reciprocally disposed in a cylinder bore of the cylinder portion 3 are connected via a connecting rod. The crankshaft 6 is driven to rotate.

  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), and a camshaft 8 including a cam 7 that opens and closes the intake valve. The cylinder head 5 is rotatably provided so as to be arranged in parallel with the crankshaft 6. A rocker arm that contacts and swings with the cam surface of the cam 7 by the rotation of the camshaft 8 is connected to the intake valve. The opening / closing operation of the exhaust valve is performed by a cam and a rocker arm attached to the camshaft 8 out of phase with the cam 7. A head cover 9 that covers a valve mechanism such as a rocker arm or a camshaft 8 is detachably attached to the cylinder head 5.

  The gear train 10 for transmitting the rotation of the crankshaft 6 to the camshaft 8 is provided on the crankshaft 6 as shown in the schematic explanatory views in FIGS. 2 and 3 and the sectional view taken along the line II in FIG. The cam drive gear 11 on the driving side, the cam driven gear 12 on the driven side provided on the camshaft 8, and the support shaft 13 provided on the cylinder block 2 in parallel with the crankshaft 6 are rotatably supported. The first idler gear 14 that is integrally formed on the outer periphery of the tip of the governor case 22 that is a rotating member and meshes with the cam drive gear 11, and the support shaft 16 that is provided in parallel with the crankshaft 6 on the cylinder block 2 are rotatably mounted on the shaft. The second idler gear 17 is supported and meshed with the first idler gear 14 and the cam driven gear 12 so as to be able to transmit power. There. The cam drive gear 11, the first idler gear 14, the second idler gear 17, and the cam driven gear 12 constituting the gear train 10 are arranged linearly.

  With this configuration, the first idler gear 14 that meshes with the cam drive gear 11 that rotates as the crankshaft 6 rotates rotates synchronously with the crankshaft 6, and the second idler gear 17 that meshes with the first idler gear 14 and the second idler gear 17 The meshed cam driven gear 12 rotates synchronously, and the camshaft 8 is driven to rotate in synchronization with the crankshaft 6 via the gear train 10. By the rotation of the camshaft 8, the intake valve and the exhaust valve are operated to open and close the intake port and the exhaust port, and a good opening / closing timing can be secured.

  On the other hand, the governor 20 has a governor case 22 having a bottomed cylindrical shape that is rotatably supported by a support shaft 13 provided in the cylinder block 2, and a first idler gear 14 integrally formed on the outer periphery of the tip. The governor case 22 is rotationally driven in synchronization with the crankshaft 6 by the first idler gear 14 that meshes with the crankshaft 11. A flyweight 25 that swings (expands) by a centrifugal force accompanying the rotation of the governor case 22 by a support shaft 24 is provided in the governor case 22. The base end portion of the flyweight 25 is in contact with a governor sleeve 26 that is provided on the support shaft 13 so as to be movable in the axial direction, 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 crankshaft 6 is synchronized with the crankshaft 6 via the first idler gear 14 that meshes with the cam drive gear 11 in response to a change in the rotational speed of the crankshaft 6 caused by this. The rotating speed of the rotating governor case 22 is changed, and the governor sleeve 26 is moved by a predetermined amount by the flyweight 25 that is swung by the centrifugal force accompanying the change in the rotating speed of the governor case 22, and the governor shaft 27, The throttle lever of the carburetor is operated via the governor lever 28 and the like, and the engine speed is adjusted.

  According to the engine 1 configured in this way, the first idler gear 14 is integrally formed on the outer periphery of the governor case 22, and the governor case 22 also serves as the first idler gear 14, so that it is arranged coaxially with the conventional crankshaft 6. The governor drive gear that has been used can be omitted, and in combination with the governor case 22 and the first idler gear 14 being supported by the single support shaft 13, the number of components can be reduced and the structure can be simplified. can get. Furthermore, the crankshaft 6 can be shortened, and the arrangement space for the conventional governor drive gear becomes unnecessary, and the axial direction of the crankshaft 6 of the crankcase 4 can be reduced. Further, by integrally forming the governor case 22 and the first idler gear 14, the radial direction of the crankshaft 6 of the crankcase 4 is reduced, the required volume of the crankcase 4 can be reduced, and the cylinder block including the crankcase 4 is included. Thus, a reduction in the manufacturing cost of the engine 1 can be expected. Furthermore, the present embodiment can be easily configured without greatly changing the existing governor 20 by forming idler gears on the outer periphery of the governor case 22.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention. For example, in the above-described embodiment, the gear train 10 includes the cam drive gear 11, the cam driven gear 12, and the two idler gears of the first idler gear 14 and the second idler gear 17 disposed between the cam drive gear 11 and the cam driven gear 12. However, the number of idler gears is not limited to two, but may be constituted by one or three or more idler gears.

1 is an overall cross-sectional view of a general-purpose engine showing an outline of an 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 a whole sectional view showing the outline of the conventional general purpose engine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder block 3 Cylinder part 4 Crankcase 6 Crankshaft 7 Cam 8 Camshaft 10 Gear train 11 Cam drive gear 12 Cam driven gear 13 Support shaft 14 1st idler gear (idler gear)
16 Support shaft 17 Second idler gear (idler gear)
20 Governor 22 Governor case (rotating member)
25 Fly Weight 26 Governor Sleeve 27 Governor Shaft 28 Governor Lever 29 Governor Rod

Claims (2)

A governor that adjusts the engine speed based on the rotation of a rotating member that is rotatably mounted to the cylinder block via a support shaft and rotates in synchronization with the crankshaft;
The cam drive gear provided on the crankshaft and the cam driven gear provided on the camshaft are provided with a gear train that rotates synchronously via an idler gear,
An engine with a governor, wherein the idler gear is integrally formed with the rotating member. A cylindrical governor case rotatably supported by a cylinder block via a support shaft, a flyweight disposed in the governor case and swinging in accordance with the rotation of the governor case, and swinging of the flyweight A governor sleeve that moves forward and backward in the axial direction of the support shaft in conjunction with, and a governor that adjusts the engine speed according to the forward and backward movement of the governor sleeve;
The cam drive gear provided on the crankshaft and the cam driven gear provided on the camshaft are provided with a gear train that rotates synchronously via an idler gear,
An engine with a governor, wherein the idler gear is integrally formed on an outer periphery of a governor case.

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