JP4382009B2 - Engine fuel supply system - Google Patents

Description

  The present invention relates to an engine fuel supply device in which an auto fuel cock is disposed between an engine case and a fuel tank fixed to the upper portion of the engine case, and the inside of the engine case and the auto fuel cock are connected by a negative pressure tube.

In order to attach the fuel cock to the bottom of the fuel tank, the fuel cock suction part is inserted into the exhaust pipe provided in the fuel tank through an oil seal made of an elastic material, and is fitted to the outer periphery of the discharge pipe and the suction part. Patent Document 1 listed below discloses that a cylindrical locking body made of a body is fastened and fixed with a fixture.
Japanese Utility Model Publication No.59-13336

  By the way, when an auto fuel cock is arranged between the engine case and the fuel tank fixed to the upper part of the engine case, and the inside of the engine case and the auto fuel cock are connected by a negative pressure tube, the lower end of the negative pressure tube is connected to the engine case. The work of connecting to the inside and the work of connecting the upper end of the negative pressure tube to the auto fuel cock are required, and there is a problem that requires a lot of labor and time for the work. In particular, when the work space between the fuel tank and the engine case is small, the above work becomes even more difficult. If sufficient work space is secured, the distance between the engine case and the fuel tank increases and the entire engine There is a problem of increasing the size.

  The present invention has been made in view of the above circumstances, and facilitates the work of connecting the interior of the engine case and the auto fuel cock with a negative pressure tube without increasing the distance between the engine case and the fuel tank. With the goal.

In order to achieve the above object, according to the first aspect of the present invention, an auto fuel cock is disposed between the engine case and a fuel tank fixed to the upper portion of the engine case, and the interior of the engine case, the auto fuel cock, In the engine fuel supply apparatus in which the negative pressure tube is connected, the first connecting portion at the upper portion of the negative pressure tube is fitted to the first negative pressure introduction joint protruding downward from the auto fuel cock fixed to the lower surface of the fuel tank. In addition, a second connecting portion at the lower part of the negative pressure tube is fitted to a second negative pressure introduction joint protruding upward from the upper surface of the engine case, and a negative pressure against the engine case is interposed between the negative pressure tube and the engine case. positioning means are provided for regulating the mounting attitude of the tube, when the fuel tank is moved downward to secure the top of the engine case The first connecting portion of the negative pressure tube in which the second connecting portion is fitted to the second negative pressure introducing joint of the engine case is located on the moving path of the first negative pressure introducing joint of the auto fuel cock. the fuel supply system for an engine which is Ru been proposed.

According to a second aspect of the invention , in addition to the configuration of the first aspect of the invention , the positioning means is a protrusion and a recess provided on one and the other of the negative pressure tube and the engine case, respectively. An engine fuel supply device is proposed.

According to the invention described in claim 3 , in addition to the structure of the invention of claim 1 or 2, a tapered portion whose outer diameter decreases downward is formed at the lower end of the first negative pressure introduction joint of the auto fuel cock. An engine fuel supply device characterized by the above is proposed.

According to the invention described in claim 4 , in addition to the configuration of any one of claims 1 to 3 , the negative pressure tube is monotonous from the first negative pressure introduction joint to the second negative pressure introduction joint. A fuel supply device for an engine, which is characterized by a downward slope, is proposed.

  In addition, the protrusion 11c and the recessed part 38d of an Example respond | correspond to the positioning means of this invention.

According to the present invention , the first connecting portion of the upper portion of the negative pressure tube is fitted to the first negative pressure introducing joint protruding downward from the auto fuel cock fixed to the lower surface of the fuel tank, and upward from the upper surface of the engine case. When the second connecting portion at the lower part of the negative pressure tube is fitted to the second negative pressure introducing joint projecting to the upper part of the engine case, when the fuel tank is moved downward to fix the upper part of the engine case, the second of the engine case Since the first negative pressure introducing joint of the auto fuel cock is automatically fitted to the first connecting portion of the negative pressure tube in which the second connecting portion is previously fitted to the negative pressure introducing joint, the fuel tank is assembled at the same time. The assembly of the negative pressure tube can be completed, and the working efficiency is greatly improved. In addition, it is necessary to provide a working space between the lower surface of the fuel tank and the upper surface of the engine case for performing the work of fitting the first and second connecting portions of the negative pressure tube to the first and second negative pressure introducing joints. Therefore, the fuel tank can be made as close as possible to the engine case to reduce the size of the entire engine.

In addition, since the positioning means for restricting the mounting posture of the negative pressure tube with respect to the engine case is provided between the negative pressure tube and the engine case, the first negative pressure introducing joint of the auto fuel cock is connected to the first connecting portion of the negative pressure tube. Can be easily fitted.

In particular , according to the second aspect of the present invention , the positioning means is constituted by the protrusion and the recess provided on one and the other of the negative pressure tube and the engine case, respectively, so that the negative pressure on the engine case is engaged by engaging the protrusion and the recess. The mounting posture of the tube can be easily and reliably regulated.

In particular , according to the invention of claim 3, since the taper portion whose outer diameter decreases downward is formed at the lower end of the first negative pressure introducing joint of the auto fuel cock, it is lowered to fix the fuel tank to the upper portion of the engine. The first negative pressure introducing joint of the auto fuel cock can be easily fitted to the first connecting portion of the negative pressure tube when moved to.

In particular , according to the invention of claim 4, since the negative pressure tube has a monotonous downward slope from the first negative pressure introduction joint to the second negative pressure introduction joint, the oil that has entered the negative pressure tube is removed by gravity. It is possible to reliably prevent entry into the auto fuel cock by discharging.

  Embodiments of the present invention will be described below based on the embodiments of the present invention shown in the accompanying drawings.

  1 to 12 show an embodiment of the present invention, FIG. 1 is a front view of a general-purpose engine, FIG. 2 is a view taken in the direction of the arrow in FIG. 1, and FIG. 4 is a view taken in the direction of arrows 4 in FIG. 3, FIG. 5 is an enlarged sectional view taken along line 5-5 in FIG. 4, FIG. 6 is an enlarged view taken in lines 6-6 in FIG. 8 is an enlarged sectional view taken along line 8-8 in FIG. 7, FIG. 9 is an enlarged sectional view taken along line 9-9 in FIGS. 6 and 10, and FIG. 10 is an enlarged arrow taken along line 10-10 in FIG. FIG. 11 is a partial view of FIG. 10, and FIG. 12 is a sectional view taken along line 12-12 of FIG.

  As shown in FIGS. 1 and 2, the single-cylinder four-cycle engine E has a slightly lower cylinder axis L so that the cylinder head 12 and the head cover 13 side are higher than the engine case 11 integrally having a crankcase and a cylinder block. It is inclined and arranged. The crankshaft 14 protrudes from one end surface of the engine case 11, and a recoil starter 16 for cranking and starting the crankshaft 14 is provided on the outer surface of the cover 15 that covers the other end surface of the engine case 11. A carburetor 17 is provided on the side of the cylinder head 12, and an intake passage 18 extending upward from the carburetor 17 is connected to an air cleaner 19. A muffler 20 is attached to the upper part of the cylinder head 12 and the head cover 13 so as to be aligned with the air cleaner 19, and a fuel tank 21 is attached to a position closer to the crankcase than the air cleaner 19 and the muffler 20.

  The fuel tank 21 is configured by integrally connecting the lower edge of the tank upper 21 a, the upper edge of the tank lower 21 b, and the upper edge of the tank holder 22 with a caulking portion 23. The tank stays 24 are fixed to the four mounting bosses 11a protruding from the engine case 11 with bolts 25, and the outer peripheral portions of the four rubber bushes 26 are supported on the upper surface of the tank stay 24. Bolts 27 that penetrate the centers of the respective rubber bushes 26 from below upward pass through the tank holder 22 and the reinforcing plate 28 and are fastened to the nuts 29, so that the fuel tank 21 is supported in an anti-vibration manner above the engine case 11. Is done.

  As shown in FIGS. 3 and 6 to 8, an auto fuel cock 30 that supplies the fuel in the fuel tank 21 to the automatic carburetor 17 during operation of the engine E is attached to the lower surface of the fuel tank 21. The auto fuel cock 30 includes a first housing 31 and a second housing 32 that are integrally coupled, and a stay 31 a (see FIG. 6) protruding from the first housing 31 is a bottom surface of the tank holder 22 by a bolt 33 and a nut 34. Fixed to. At this time, the upper part of the auto fuel cock 30 protrudes upward through the opening 22a (see FIG. 7) of the tank holder 22, and the lower part of the auto fuel cock 30 opens to the opening 24a of the tank stay 24 (see FIGS. 3 and 6). Protrudes downward through.

  As best shown in FIG. 8, the first housing 31 of the auto fuel cock 30 includes a fuel inlet joint 31b, a fuel outlet joint 31c, and a valve seat 31d formed between the fuel inlet joint 31b and the fuel outlet joint 31c. And a disk-shaped diaphragm support portion 31e. The second housing 32 includes a first negative pressure introduction joint 32a, a negative pressure chamber 32b connected to the first negative pressure introduction joint 32a, and a disk-shaped diaphragm support portion 32c. The fuel inlet joint 31b is connected to the joint 36 provided on the lower surface of the fuel tank 21 via the first fuel hose 35, the fuel outlet joint 31c is connected to the carburetor 17 via the second fuel hose 37, and further the first negative hose 35b. The pressure introducing joint 32 a is connected to the second negative pressure introducing joint 11 b of the engine case 11 through a rubber negative pressure tube 38. By using the rubber negative pressure tube 38, the degree of freedom of the layout of the fuel tank 21 with respect to the engine case 11 can be increased.

  An annular diaphragm support member 39 is sandwiched between the diaphragm support portion 31e of the first housing 31 and the diaphragm support portion 32c of the second housing 32, and the diaphragm support portion 31e and the diaphragm support member 39 of the first housing 31 The outer peripheral portion of the first diaphragm 40 is fixed via the seal member 41 during the interval, and the outer peripheral portion of the second diaphragm 42 is sealed between the diaphragm support portion 32c and the diaphragm support member 39 of the second housing 32. It is fixed via 43. A first and second diaphragms 40 and 42; a spacer block 44 sandwiched between the central portions of the first and second diaphragms 40 and 42; and a disc-shaped spring seat 45 that contacts the back surface of the second diaphragm 42; Are fixed together by a rivet 46 extending therethrough.

  A valve seat forming member 48 is fitted via a spacer plate 47 between the first negative pressure introducing joint 32a and the negative pressure chamber 32b of the second housing 32, and the valve seat forming member 48, the spring seat 45, The valve body 49 a formed at the central portion of the first diaphragm 40 is urged in the direction in which it is seated on the valve seat 31 d of the first housing 31. One end of a reed valve 50 that can be seated on a valve seat 48b facing a through hole 48a that passes through the central portion of the valve seat forming member 48, and one end of a stopper 51 that covers the outside and restricts the movable range of the reed valve 50. The valve seat forming member 48 is fixed with bolts (not shown). The reed valve 50 is formed with a minute through hole 50a that allows the first negative pressure introducing joint 32a and the negative pressure chamber 32b to communicate with each other.

  As is apparent from FIGS. 7 and 8, a tapered portion 32d for facilitating insertion of the negative pressure tube 38 is formed at the lower end of the first negative pressure introducing joint 32a. A letter-shaped notch 32e is formed. The negative pressure tube 38 extends in the vertical direction and is inserted into the first negative pressure introduction joint 32a, and the second connection portion 38b extends in the vertical direction and is inserted into the second negative pressure introduction joint 11b. And an intermediate portion 38c extending obliquely downward from the lower end of the first connecting portion 38a to the upper end of the second connecting portion 38b. The intermediate connecting portion 38c is formed in a substantially crank shape, and has a linear recess on the bottom surface of the first connecting portion 38a. 38d is formed. On the other hand, a linear protrusion 11c is formed on the upper surface of the engine case 11 facing the bottom surface of the first connecting portion 38a of the negative pressure tube 38, and is fitted into the linear recess 38d. The negative pressure tube 38 is positioned in the rotational direction around the vertical axis by the engagement.

  As apparent from FIGS. 6 and 9, the breather device 52 provided on the side surface of the engine case 11 includes a breather chamber 54 surrounded by an annular peripheral wall 11 d and a cover 53, and one end portion of the breather chamber 54. The breather passage 11e opens. One end of the reed valve 55 that can be seated on the valve seat 11f formed in the opening of the breather passage 11e and one end of the stopper 56 that regulates the movable range of the reed valve 55 are fixed to the inner wall of the breather chamber 54 with bolts 57. The A joint 53a is formed in the cover 53 so as to face the other end of the breather chamber 54 far from the breather passage 11e, and the joint 53a is connected to the intake system of the engine E through the breather pipe 58. In the breather chamber 54, two ribs 11g and 11h are projected to form a labyrinth 59 between the breather passage 11e and the joint 53a. The bottom of the breather chamber 54 communicates with the internal space of the engine case 11 through the oil return hole 11i. A communication hole 11j passing through the inside of the second negative pressure introducing joint 11b into which the second connecting portion 38b of the negative pressure tube 38 is fitted communicates with the breather passage 11e.

  Next, the structure of the gas-liquid separator 61 of the engine E will be described with reference to FIGS.

  The crankshaft 14 of the engine E has a pin portion 14a connected to the piston 63 via a connecting rod 62, one journal portion 14b supported by the engine case 11 via a ball bearing 64, and the other journal. The part 14 c is supported via a ball bearing 67 on a bearing holder 66 fixed with six bolts 65 in the engine case 11. A cover member 68 is fixed to the opening 11k of the engine case 11 with nine bolts 69 so as to cover the front surface of the bearing holder 66, and an oil stirring chamber 70 is defined between the cover member 68 and the bearing holder 66. The

  Note that both ends of the primary balancer shaft 73 (see FIG. 12) are supported between the engine case 11 and the bearing holder 66 via a pair of ball bearings 71 and 72, and a drive gear 74 provided on the crankshaft 14. Meshes with a driven gear 75 provided on the primary balancer shaft 73, so that the primary balancer shaft 73 rotates at the same speed as the rotational speed of the crankshaft 14.

  A rotor 77 is rotatably supported at the bottom of the oil agitating chamber 70 via a rotor shaft 76, and a driven gear 78 provided on the rotor shaft 76 is engaged with a drive gear 79 provided on the crankshaft 14. The rotor 77 is rotationally driven by the shaft 14. A timing belt 81 wound around a drive sprocket 80 provided on the crankshaft 14 is connected to a driven sprocket (not shown) provided on the cylinder head 12.

  As apparent from FIGS. 10 and 11, the first rib 66 a that surrounds a part of the outer periphery of the rotor 77 and the second rib that surrounds a part of the outer periphery of the drive gear 79 and the drive sprocket 80 are provided on the side surface of the bearing holder 66. 66b, a third rib 66c extending along the lower surface of the lower chord of the timing belt 81 and the end of the first rib 66a, and an upper surface of the upper chord of the timing belt 81 connected to the end of the second rib 66b. , And an independent fifth rib 66e extending from the vicinity of the connecting portion between the second rib 66b and the fourth rib 66d in an inclined direction opposite to the inclination direction of the fourth rib 66d. The A first rib 68 a and a second rib 68 b that are substantially parallel to the fourth rib 66 d and the fifth rib 66 e of the bearing holder 66 protrude from the side surface of the cover member 68.

  A region surrounded by the first to fourth ribs 66a to 66d of the bearing holder 66 is an oil stirring chamber 70, and the fourth and fifth ribs 66d of the bearing holder 66 are disposed outside the first to fourth ribs 66a to 66d. , 66e and the first and second ribs 68a, 68b of the cover member 68 are partitioned into a gas-liquid separation chamber 83 having a labyrinth 82. The upper part of the gas-liquid separation chamber 83 communicates with the breather device 52 via the breather passage 11e (see FIG. 9).

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  In FIG. 10, when the engine E is operated, the rotor 77 connected to the crankshaft 14 via the drive gear 79 and the driven gear 78 rotates inside the oil stirring chamber 70, and the oil accumulated at the bottom of the oil stirring chamber 70 is removed. Raise and scatter. The scattered oil is guided between the third and fourth ribs 66 c and 66 d along the timing belt 81 by the first and second ribs 66 a and 66 b of the bearing holder 66, and is attached to the timing belt 81 there and attached to the cylinder head 12. It is supplied to a valve operating chamber (not shown) to lubricate the valve operating mechanism. The air containing oil mist generated in the oil stirring chamber 70 is constituted by the fourth and fifth ribs 66 d and 66 e of the bearing holder 66 and the first and second ribs 68 a and 68 b of the cover member 68 in the gas-liquid separation chamber 83. The oil that has passed through the labyrinth 82 and has been separated during this time falls along the first and second ribs 66a and 66b, and is returned to the bottom of the oil stirring chamber 70.

  A bearing holder 66 having a ball bearing 67 for supporting the crankshaft 14 is fixed so as to face the opening 11k of the engine case 11, and a gas-liquid separation is performed between the cover member 68 coupled to the opening 11k and the bearing holder 66. Since the chamber 83 is formed, the bearing holder 68 can be used as a part of the wall surface of the gas-liquid separation chamber 83. Accordingly, the number of parts can be increased as compared with the case where a part of the wall surface of the gas-liquid separation chamber 83 is configured by a special member, and the wall surface of the gas-liquid separation chamber 83 is formed by a partition wall formed integrally with the engine case 11. The engine case 11 can be reduced in size, weight, and shape as compared with a case where a part of the engine case 11 is configured.

  Moreover, since the labyrinth 82 is provided in the gas-liquid separation chamber 83, oil mist contained in the air in the engine case 11 can be effectively separated. In particular, the fourth and fifth ribs 66d and 66e protruding from the bearing holder 66 side overlap with the first and second ribs 68a and 68b protruding from the cover member 68 side by a distance α (see FIG. 9). Since the labyrinth 82 is configured as described above, the labyrinth 82 can be configured with a simple structure to further enhance the gas-liquid separation effect.

  In FIG. 9, the air from which the oil mist has been removed by the labyrinth 82 of the gas-liquid separation chamber 83 passes through the breather passage 11 e and the reed valve 55 of the breather device 52 and is supplied to the breather chamber 54. That is, the pressure pulsation generated by the reciprocating motion of the piston 63 is transmitted to the breather passage 11e. When the breather passage 11e becomes positive pressure, the reed valve 55 is opened and the reed valve becomes negative pressure. When the valve 55 is closed, the air in the breather passage 11e is supplied to the breather chamber 54.

  In FIG. 6, while the air supplied to the breather chamber 54 passes through the labyrinth 59 constituted by the ribs 11g and 11h, the oil component that cannot be separated by the gas-liquid separator 61 is further separated, and the breather chamber 54 is separated. Is returned to the bottom of the engine case 11 through an oil return hole 11i provided in the bottom of the engine. Since air separated from the oil mist by the gas-liquid separator 61 is guided to the breather device 52 through the breather passage 11e and further gas-liquid separation is performed, oil consumption can be further reduced. The air from which the oil mist has been removed in this manner includes fuel vapor blown from the combustion chamber into the engine case 11. The air containing this fuel vapor is the joint 53 a of the cover 53 and the breather pipe 58. Then, it is returned to the intake system of the engine E, and the fuel vapor is burned together with the air-fuel mixture to prevent the emission to the atmosphere.

  In FIG. 9, the pressure pulsation in the engine case 11 is transmitted to the first negative pressure introduction joint 32 a of the auto fuel cock 30 through the breather passage 11 e, the communication hole 11 j and the negative pressure tube 38. In FIG. 8, when the pressure transmitted to the first negative pressure introducing joint 32a of the auto fuel cock 30 becomes negative pressure, the reed valve 50 is separated from the valve seat 48b and the negative pressure chamber 32b becomes negative pressure. When the pressure transmitted to the negative pressure introducing joint 32a becomes positive, the reed valve 50 is seated on the valve seat 48b and the negative pressure in the negative pressure chamber 32b is maintained. Thus, the negative pressure chamber 32b is always maintained at a negative pressure during operation of the engine E, so the first and second diaphragms 40 and 42 move to the left against the resilient force of the valve spring 49, and the first The valve body 40a formed on the diaphragm 40 is separated from the valve seat 31d. As a result, the fuel in the fuel tank 21 passes through the first fuel hose 35, the fuel inlet joint 31b, the gap between the valve seat 31d and the valve body 40a, the fuel outlet joint 31c, and the second fuel hose 37. Supplied to the carburetor 17.

  When the engine E is stopped and the pressure pulsation in the breather passage 11e disappears, the first and second diaphragms 40 and 42 are urged to the right in FIG. The reed valve 50 sucked in the direction is seated on the valve seat 48b and the negative pressure chamber 32b is sealed. However, since air flows into the negative pressure chamber 32b from the first negative pressure introduction joint 32a through the small through hole 50a provided in the valve seat 50, the valve body 40a is seated on the valve seat 31d by the elastic force of the valve spring 49. Then, the auto fuel cock 30 is closed. Accordingly, the fuel supply from the fuel tank 21 to the carburetor 17 can be automatically stopped with the stop of the engine E.

  The negative pressure tube 38 is coupled to the first and second negative pressure introduction joints 32a and 11b in the following procedure. That is, the tank stay 24 is assembled in advance to the tank holder 22 of the fuel tank 21 via the rubber bushes 26, and further, the auto fuel cock 30 and the first fuel hose 35 are assembled in advance. On the other hand, the second connecting portion 38b of the negative pressure tube 38 is fitted in advance to the second negative pressure introducing joint 11b of the engine case 11. At this time, the negative pressure tube 38 can be positioned in the rotational direction by engaging the recess 38d on the bottom surface of the first connecting portion 38a of the negative pressure tube 38 with the protrusion 11c of the engine case 11 (see FIG. 7). . From this state, the fuel tank 21 is approached from above with respect to the engine case 11, and the first connecting portion 38 a of the negative pressure tube 38 is fitted to the first negative pressure introduction joint 32 a of the auto fuel cock 30, and then the tank stay 24 is fixed to the engine case 11 with bolts 25. Then, the second fuel hose 37 connected to the carburetor 17 is fitted to the fuel outlet joint 31c to complete the assembly.

  In this way, the negative pressure tube 38 can be connected to the first and second negative pressure introduction joints 32a and 11b simply by bringing the fuel tank 21 closer to the engine case 11 from above. Assembly work is simplified. Further, since the recess 38d of the negative pressure tube 38 is positioned by engaging with the protrusion 11c of the engine case 11, the first connection portion 38a of the negative pressure tube 38 is connected to the first negative pressure introduction joint 32a of the auto fuel cock 30. The mating operation becomes easy. Moreover, since the negative pressure tube 38 once attached is restricted from moving in the vertical direction and cannot be removed unless the fuel tank 21 is removed, it is not necessary to prevent the end of the negative pressure tube 38 from being removed with a clip or the like.

  If an attempt is made to assemble the negative pressure tube 38 after the fuel tank 21 is fixed to the engine case 11, the negative pressure tube 38 is bent and fitted to the first and second negative pressure introduction joints 32a and 11b. Not only is the working space required, but also the negative pressure tube 38 itself increases in size, so that the fuel tank 21 cannot be placed close to the engine case 11 and the entire engine E is increased in size.

  By the way, if the oil mist in the engine case 11 accumulates in the negative pressure tube 38 or the first negative pressure introducing joint 32a, the pressure pulsation in the breather passage 11e can be transmitted to the negative pressure chamber 32b of the auto fuel cock 30. There is a possibility that the auto fuel cock 30 may malfunction. However, according to the present embodiment, air from which most of the oil mist has been removed by the gas-liquid separator 61 is supplied to the breather passage 11e, and the pressure pulsation in the breather passage 11e is guided to the auto fuel cock 30. The malfunction of the auto fuel cock 30 can be prevented beforehand.

  In particular, the breather passage 11e that supplies the air that has passed through the gas-liquid separator 61 to the breather device 52 is provided in the upper part of the engine case 11, so that oil mist can be more effectively prevented from entering the breather passage 11e. can do. In addition, since the auto fuel cock 30 is operated using the pressure pulsation of the breather passage 11e, it is not necessary to form a special passage for transmitting the pressure pulsation to the auto fuel cock 30.

  The negative pressure tube 38 extends in the vertical direction and is inserted into the first negative pressure introduction joint 32a, and the second connection portion 38b extends in the vertical direction and is inserted into the second negative pressure introduction joint 11b. And an intermediate portion 38c extending obliquely downward from the lower end of the first connecting portion 38a to the upper end of the second connecting portion 38b, even if oil mist enters the negative pressure tube 38, The oil mist does not stay in the negative pressure tube 38 and is discharged to the breather passage 11e by gravity, so that a situation in which pressure pulsation is not transmitted to the auto fuel cock 30 can be avoided.

  Further, since the tapered portion 32d is formed at the lower end of the first negative pressure introducing joint 32a of the auto fuel cock 30, not only the insertion work of the negative pressure tube 38 into the first connecting portion 38a is facilitated, but also the tapered portion 32d. Since the notch 32e is formed, even when the engine E is tilted, even when oil accumulates at the lower end of the first connecting portion 38a as shown by the chain line O in FIG. 7, the first negative pressure is introduced by the action of the notch 32e. It is possible to prevent the joint 32a from being blocked. In particular, since the notch 32e is opened toward the intermediate portion 38c side of the negative pressure tube 38, the notch 32e can be more reliably prevented from being immersed in the oil.

  If the first negative pressure introduction joint 32a is cut at the upper end position of the tapered portion 32d (that is, the upper end position of the notch 32e), the same effect as that provided by the notch 32e can be obtained. Then, since the tapered portion 32d is eliminated, it becomes difficult to insert the negative pressure tube 38.

  Further, the auto fuel cock 30 is operated not by the intake negative pressure of the engine E but by a negative pressure in the engine case 11 that is higher than that, so that a sufficient negative pressure is generated only by the cranking by the recoil starter 16 to the carburetor 17. Fuel can be supplied. In particular, by employing the two first and second diaphragms 40 and 42, the auto fuel cock 30 can be reliably operated even with a small negative pressure.

  Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.

  For example, although the general-purpose engine E has been described in the embodiment, the present invention can be applied to an engine for any application.

  In the embodiment, the concave portion 38d provided in the negative pressure tube 38 and the protrusion 11c provided in the engine case 11 are illustrated as positioning means. However, the positional relationship between the concave portion and the protrusion may be reversed. The shape is also arbitrary.

Front view of general-purpose engine 2 direction view of FIG. 3-3 enlarged sectional view of FIG. 4 direction arrow view of FIG. FIG. 4 is an enlarged sectional view taken along line 5-5. 6-6 enlarged arrow view of FIG. 7-7 enlarged sectional view of line 7-7 FIG. 7 is an enlarged sectional view taken along line 8-8. 9 and 9 is an enlarged cross-sectional view taken along line 9-9 of FIG. FIG. 10 is an enlarged view taken along line 10-10 in FIG. Partial view of FIG. 12-12 sectional view of FIG.

11 Engine case 11b Second negative pressure introduction joint 11c Protrusion (positioning means)
21 Fuel tank 30 Auto fuel cock 32a First negative pressure introduction joint 32d Taper portion 38 Negative pressure tube 38a First connection portion 38b Second connection portion 38d Recess (Positioning means)

Claims (4)

An auto fuel cock (30) is disposed between the engine case (11) and a fuel tank (21) fixed to the upper portion thereof, and the inside of the engine case (11) and the auto fuel cock (30) are connected to a negative pressure tube ( 38) In the engine fuel supply device connected in
The first connecting portion (38a) at the upper portion of the negative pressure tube (38) is fitted into the first negative pressure introducing joint (32a) protruding downward from the auto fuel cock (30) fixed to the lower surface of the fuel tank (21). In addition, the second connecting portion (38b) below the negative pressure tube (38) is fitted to the second negative pressure introducing joint (11b) protruding upward from the upper surface of the engine case (11), and the negative pressure Positioning means is provided between the tube (38) and the engine case (11) to regulate the mounting posture of the negative pressure tube (38) with respect to the engine case (11), and the fuel tank (21) is attached to the engine case (11). The first negative pressure tube (38) having the second connecting portion (38b) fitted to the second negative pressure introducing joint (11b) of the engine case (11) when moved downward to be fixed to the upper portion. Forming portion (38a) is a first negative pressure introduction joint (32a) fuel supply equipment of the engine, characterized in that located on a moving path of the auto fuel cock (30). 2. The engine fuel according to claim 1 , wherein the positioning means is a protrusion (11 c) and a recess (38 d) provided on one and the other of the negative pressure tube (38) and the engine case (11), respectively. Feeding device. 3. The engine according to claim 1, wherein a tapered portion (32 d) whose outer diameter decreases downward is formed at a lower end of the first negative pressure introduction joint (32 a) of the auto fuel cock (30). Fuel supply device. Negative pressure tube (38) is characterized that it is monotonic downward slope from the first negative pressure introduction joint (32a) to a second negative pressure introduction joint (11b), one of claims 1 to 3 The engine fuel supply device according to claim 1.

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