JP4223919B2 - Engine with integrated cooling fan and starting pulley - Google Patents

Description

  The present invention relates to an engine mounted as a drive source on a working machine such as a lawn mower, and more particularly to an engine in which a cooling fan and a starting pulley are integrated.

Conventionally, a vertical axis (vertical) engine is usually used as a drive source for a working machine such as a lawn mower. In this engine, the crankshaft is set to penetrate the inside of the crankcase in the vertical direction, and the lower end portion of the crankshaft protruding downward from the crankcase serves as an output shaft. As an example of a cooling fan and starting pulley mounting structure in an engine having such a configuration, there is one shown in FIG. 11 (see, for example, Patent Document 1). In FIG. 11, a cooling fan 72 integrally formed with a flywheel 73 is attached to an upper end portion 71 of a crankshaft 70 penetrating in the vertical direction, and starting from a recoil starter (not shown) with respect to the cooling fan 72. A starting pulley 74 that receives force is fixed by a mounting bolt 75. The cooling fan 72 is formed by integrally forming a casting material such as cast iron with the flywheel 73 by a casting method such as centrifugal casting or die casting, thereby reducing the number of parts.
Japanese Utility Model Publication No. 5-24921 (summary and drawing of the first page)

  However, when the flywheel 73 and the cooling fan 72 are integrally formed by casting, in order to improve the performance of the cooling fan 72, it is necessary to reduce the thickness of the rotating blades of the cooling fan 72 as much as possible. Is required to increase its inertial force by increasing its weight. Therefore, the thin cooling fan 72 having a complicated shape is formed on the large flywheel 73, which makes casting difficult.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an engine in which a cooling fan and a starting pulley are integrated, which makes it possible to reduce the thickness of the rotating blades of the cooling fan while increasing the weight of the flywheel to increase the rotational inertia force. There is to do.

In order to achieve the above object, an engine according to the present invention includes a flywheel fixed to a crankshaft, a cooling fan formed separately from the flywheel and fixed to the crankshaft, and a recoil starter. A fan with a pulley integrally formed with a starting pulley that engages with a pawl and receives a starting force, and a member that is fixed to a crankshaft together with the fan with a pulley and engages with the engaging pawl in the starting pulley. A bracket for pressing the groove between the mating protrusions in the direction of the rotation axis is provided.

According to this configuration, it is not the flywheel but the starting pulley that is integrally formed with the cooling fan. In other words, the flywheel is separate from the cooling fan, and is configured as a single part by casting, for example, so that a large rotational inertia force can be applied. On the other hand, a fan with a pulley in which a cooling fan and a starting pulley are integrally formed can be integrally formed by, for example, resin molding. Therefore, a cooling fan is integrally formed with a flywheel, and a separate pulley is attached to the flywheel. Compared to the conventional case, the number of parts does not increase. In addition, due to the characteristics of resin molding, the rotating blades of the cooling fan can be easily thinned to improve the blowing performance. Moreover, in the case of the resin molding, a sufficient strength can be imparted to the cooling fan and the starting pulley by using a polyamide resin, a glass fiber reinforced resin, or the like. Further, since the fan with pulley is an integrated body of the cooling fan and the pulley, the mounting performance to the crankshaft is improved, and the cooling fan can be easily removed during maintenance such as cleaning the pulley and checking the pulley. Further, since the groove between the engaging protrusions is pressed in the axial direction by the placket, deformation of the engaging protrusion due to the engagement between the engaging claw and the engaging protrusion is suppressed. In addition, when the bracket is fixed to the crankshaft, the fan with pulley is also fixed to the crankshaft at the same time, and it is not necessary to fix the bracket and fan with pulley to the crankshaft separately. Is possible.

  In a preferred embodiment of the present invention, a dust-proof screen member is provided on the axially outer side of the fan with pulley, and extends in the axial direction adjacent to the outer surface of the engagement protrusion on the inner peripheral portion of the screen member. It has an inner wall.

  According to this configuration, the dust-proof screen member rotates together with the fan with the pulley, and suppresses dust such as turf dust from entering the fan together with the air when air is sucked. Furthermore, since the inner peripheral wall of the screen member is close to the outer surface of the engaging protrusion of the pulley, it is possible to suppress the engaging protrusion from being deformed radially outward when engaged with the engaging claw.

  In a preferred embodiment of the present invention, the pulley-equipped fan and the bracket are fastened together with the crankshaft by a common fastening member.

  According to this configuration, the fan with pulley and the bracket can be simultaneously attached to the crankshaft by one fastening member, so that not only the workability is good, but also a fastening member dedicated for each part is not required. The score can be reduced.

  As described above, according to the present invention, since the cooling fan and the starting pulley are formed, for example, by molding the resin with a resin, the rotating blades of the cooling fan can be easily thinned to improve the blowing performance. Can be improved. In addition, since the fan with pulleys can be handled as an integrated body in which the cooling fan and the pulley are integrated, attachment to the crankshaft and removal during maintenance can be easily performed. On the other hand, the flywheel is a single item, and the weight of the flywheel can be increased to increase the inertial force of rotation.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a vertical axis engine in which a cooling fan and a starting pulley according to an embodiment of the present invention are integrated. In FIG. 1, a vertical axis engine E is configured such that a crankshaft 1 is set so as to penetrate the inside of a crankcase 5 in the vertical direction, and the crankshaft 1 reciprocates in a cylinder 3 in a horizontal direction. A horizontally disposed piston 2 is connected. A cylinder head 4 is attached to the end of the cylinder 3, and a lower end 1a of the crankshaft 1 protruding downward from the crankcase 5 is used as an output shaft. For example, when the engine E is mounted on a lawn mower 21 that is an example of a work machine, a cutter blade 22 is attached. The upper part of the engine E, that is, the upper part of the cylinder 3, the cylinder head 4 and the crankcase 5 is covered with an engine cover 6 including an air cleaner 23 and a fuel tank 24.

  The upper end portion 1b of the crankshaft 1 protruding upward from the crankcase 5 is provided with a fan F with a pulley in which a cooling fan 8 housed in a fan housing 19 and a starting pulley 9 are integrated by resin molding, and a fly The wheel 7 is fixed. A dust-proof screen member 10 is mounted on the outside in the axial direction of the fan F with pulley, that is, on the upper side in FIG. The fan housing 19 is attached to the engine cover 6 and guides the cooling air from the cooling fan 8 to the cylinder 3, the cylinder head 4 and the crankcase 5.

  The fan F with pulley is obtained as a part in which the starting pulley 9 and the cooling fan 8 are integrally molded by resin molding. As shown in FIG. 2, the fan F with pulley has a cylindrical starting pulley 9 erected in the center, and a fan 8 composed of a large number of rotating blades 81 formed around the pulley. A reinforcing ring 82 that prevents deformation of the rotary blade 81 due to centrifugal force during rotation is provided over the entire outermost circumference. As shown in FIG. 3, the rotary blade 81 is formed in a thin and curved plate shape. The starting pulley 9 has four engagement protrusions 91 and a groove (engagement groove) 92 provided between the adjacent engagement protrusions 91, 91. The engagement protrusion 91 is shown in FIG. As shown in FIG. As a resin material used for resin molding of the fan F with a pulley, for example, a high-strength resin material such as polyamide resin or glass fiber reinforced resin is suitable, and thus the cooling fan 8 and the starting pulley 9 have sufficient strength. I am letting.

  5 and 6 show a dust-proof screen member 10. This is made, for example, by punching a thin metal plate, and has a dish-like body having an opening 10a in the center as shown in FIG. 5, and the start pulley as shown in FIG. 9 is provided with an inner peripheral wall 10b extending in the axial direction in the vicinity of the radially outer surface of the engagement protrusion 91 (FIG. 2), and four positioning protrusions 10c that are bent at the lower end of the inner peripheral wall 10b and extend inward in the radial direction. Are integrally formed. A bent piece 10d is formed on the outer peripheral portion of the screen member 10 for cutting grass and the like. A large number of small holes 10 e are provided between the inner periphery and the outer periphery of the screen member 10. By covering the entire upper surface of the cooling fan 8 with the screen member 10 for dust prevention, intrusion of dust such as grass dust into the cooling fan 8 is prevented, and a relatively long lawn that tries to enter the cooling fan 8. Waste is cut into fine pieces.

  FIGS. 7A to 7C show a bracket 11 for supporting the pulley 9 (FIG. 2), which is obtained, for example, by pressing a metal plate into a cup shape. As shown in FIG. 7B, the bracket 11 is formed with a plurality of petal-like tongue pieces 11a projecting outward from the upper portion thereof, and a valley portion 11b is formed between the adjacent tongue pieces 11a and 11a. Is formed. As shown in FIG. 7A, a total of four tongue pieces 11a are formed, for example, 90 ° apart from each other in the circumferential direction, and four trough portions 11b are provided between adjacent tongue pieces 11a and 11a. Is formed. This bracket 11 is fixed to the crankshaft 1 together with the fan F with pulley of FIG. As shown in FIG. 7C, a locking projection 11d is formed on the bottom of the bracket 11 to engage with the flywheel 7 and prevent rotation.

  A recoil starter 14 is attached to the upper portion of the engine cover 6 of FIG. 1 using this as an attachment base. As shown in FIG. 8, the recoil starter 14 has a substantially rectangular starter case 14a in plan view, and as shown in FIG. 9, an engaging claw provided in the starter case 14a so as to protrude laterally. By engaging 14b with the engagement protrusion 91 of the pulley 9 of FIG. 2, the pulley 9 receives the starting force generated by manually operating the recoil starter 14 of FIG.

  The starter case 14a is made of resin, and as shown in FIG. 8, a large number of air intake holes 14c and 14d are formed on the upper surface and the outer peripheral surface thereof, and the mounting holes 14e provided at the four corners of the outer periphery are formed in FIG. As shown, the bolt 15 is inserted and fastened to the engine cover 6. As shown in FIG. 9, the recoil starter 14 is provided with the engaging claws 14b laterally orthogonal to the axial direction, and the engaging claws 14b are pushed down by the spring force of the spring 14f attached in the axial direction. Thus, the protrusion 14bb of the engaging claw 14b enters the guide groove 14h. When the engagement claw 1b is rotated by pulling the rope 26, the engagement claw 1b is guided radially by the guide groove 14b and engaged with the engagement protrusion 91 of the pulley 9. The pulley 9 receives a rotational force.

  The fan-equipped fan F is attached as follows. That is, the flywheel 7 is fitted to the upper end portion 1b of the crankshaft 1 in FIG. 1, and the fan F with a pulley is placed on the upper surface (axially outer surface) of the flywheel 7, and the screen member 10 is placed thereon. At this time, the positioning projection piece 10c of the screen member 10 for dust prevention of FIG. 5 is placed in the engagement groove 92 corresponding to the valley between the plurality of engagement projections 91 of the pulley 9 shown in FIG.

  Subsequently, the tongue pieces 11a and 11a of the petal-like bracket 11 shown in FIGS. 7A to 7C are fitted into the engagement groove 92 (FIG. 2) from above the positioning protrusion 10c. Is placed on the upper end 1b of the crankshaft 1 of FIG. Then, a fastening member 12 such as a mounting bolt is inserted into a mounting hole 11c provided in the center of the bottom portion through a washer 13, and is screwed into a screw hole of the upper end portion 1b of the crankshaft 1. The flywheel 7, the fan F with pulley, and the screen member 10 are fastened and fixed together with the fan F with pulley being in contact with the fan F.

  Next, when removing the fan 7 with pulley, the bolt 15 is removed and the recoil starter 14 is removed from the engine cover 6 to expose the fan F with pulley to the outside. Subsequently, the mounting bolt 12 is loosened and the bracket 11 is removed, and maintenance such as cleaning of the fan F with pulley and inspection of the pulley 9 is performed. At that time, as shown in FIG. An anti-rotation tool 16 such as a screwdriver is passed between 92 and is engaged with engagement protrusions 91 and 91 so as to prevent the pulley 9 from rotating. In this state, the mounting bolt 12 is loosened and removed using a tool such as a wrench. At this time, since the engaging protrusion 91 is made of resin, the engaging protrusion 91 is apt to be squeezed by the tool 16 and bent outwardly in the radial direction, but the locking protrusion 91 is likely to fall down. , And the deformation outward in the radial direction is prevented. Next, the bracket 11, the screen member 10, and the fan F with pulley of FIG. 1 are taken out in this order. After cleaning the fan F, each part is attached again in the reverse procedure. During this maintenance and inspection, the pulley-equipped fan F can be handled as a single unit, so that it can be easily taken out and attached.

  In the above configuration, the fan with pulley F, in which the cooling fan 8 and the starting pulley 9 shown in FIG. 1 are integrated, is separate from the flywheel 7 and can be molded with resin, so that the cooling fan 8 of FIG. The rotating blade 81 can be made thin to improve the blowing performance. In addition, the fan with pulley F, in which the cooling fan 8 is integrally formed, can be handled as an integral part in addition to the reduction in the number of parts by integration, so that it can be attached to the crankshaft 1 in FIG. Easy to do. Furthermore, the flywheel 7 can be increased in weight and the inertial force can be increased. Further, since the groove between the engaging protrusions 91 and 91 of the pulley 9 is pressed in the axial direction by the tongue piece 11 a of the bracket 11, the engagement force due to the impact force when the engaging claw 14 b engages with the engaging protrusion 91 is applied. The deformation of the joint protrusion 91 is suppressed.

  The present invention can be applied not only to the vertical axis engine as in the above embodiment, but also to a horizontal axis engine.

It is front sectional drawing which shows the engine provided with the fan with a pulley concerning one Embodiment of this invention. It is a perspective view which shows the fan with the said pulley. It is a front view of the fan with the same pulley. It is sectional drawing along the IV-IV line of FIG. It is a front view which shows the screen for dust prevention of the engine. It is sectional drawing along the VI-VI line of FIG. The bracket of the engine is shown, (A) is a plan view, (B) is a side view, and (C) is a cross-sectional view taken along line VII-VII in (A). It is a top view which shows the recoil starter of the same engine. It is sectional drawing along the IX-IX line of FIG. It is an expansion perspective view explaining the removal operation | work of the fastening member which attaches a cooling fan. It is a longitudinal cross-sectional view which shows an example of the attachment structure of the conventional cooling fan and the starting pulley.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Crankshaft 5 ... Crankcase 6 ... Engine cover 8 ... Cooling fan 9 ... Pulley for starting 10 ... Screen member 10b ... Inner peripheral wall 11 ... Bracket 12 ... Mounting bolt (fastening member)
DESCRIPTION OF SYMBOLS 14 ... Recoil starter 14b ... Engagement claw 91 ... Engagement protrusion 92 ... Groove E ... Engine F ... Fan with pulley

Claims (3)

A flywheel fixed to a crankshaft, and a starter that is formed separately from the flywheel and that receives a starting force by engaging a cooling fan fixed to the crankshaft and an engaging claw of a recoil starter A fan with a pulley integrally formed with a pulley ;
An engine comprising: a bracket that is fixed to a crankshaft together with the pulley-equipped fan, and that presses a groove between engagement protrusions that engage with the engagement claw in the start pulley in the direction of the rotation axis . 2. The dust-proof screen member mounted on the outer side in the axial direction of the fan with pulleys according to claim 1 , wherein an inner peripheral wall extending in the axial direction in the vicinity of the outer surface of the engaging projection is provided on the inner peripheral portion of the screen member. Has an engine. 3. The engine according to claim 1, wherein the fan with pulley and the bracket are fastened together with the crankshaft by a common fastening member.

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