JP2008063983A - Insulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulator capable of simplifying a communicating structure and realizing space saving around an engine. <P>SOLUTION: A housing part 5 is integrally molded and provided on a lower part of a heat insulating part 20. A part of a housing 64 of an accelerating pump 6 is constituted on this housing part 5. Consequently, it is possible to arrange the accelerating pump 6 in the circumference of the insulator 2 which used to be conventionally a dead space and to realize the space saving by eliminating a setting space dedicated to the accelerating pump. Additionally, it is possible to reduce length of piping and to simplify the communicating structure even in using the piping to communicate an insulator leading air passage 21 and the accelerating pump 6 to each other as the accelerating pump 6 is immediately arranged around the heat insulating part 20. Furthermore, it is possible to reduce the number of parts, to reduce cost and to facilitate assembly of the accelerating pump 6 as the housing part 5 is integrally formed with the heat insulating part 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an insulator for an engine, and more particularly to an insulator used in a stratified scavenging two-cycle engine.

  In the two-cycle engine, the exhaust port and the scavenging port are opened and closed by a piston. When the exhaust port is opened by the lowering of the piston, the combustion gas is discharged as exhaust gas, and the air-fuel mixture in the crank chamber flows into the cylinder through the scavenging passage from the scavenging port opened almost simultaneously. The inflowing air-fuel mixture flows out, albeit slightly, while scavenging the combustion gas remaining in the cylinder until the piston closes the exhaust port. Therefore, the unburned fuel in the air-fuel mixture will be discharged together with the exhaust gas, but this will cause a decrease in fuel consumption due to fuel loss and prevent unburned fuel from being discharged outside from the viewpoint of environmental conservation. A complex muffler structure was required.

  In order to solve this problem, a stratified scavenging two-cycle engine has been proposed. The stratified scavenging two-cycle engine includes a leading air passage communicating with the scavenging passage. As a result, prior to scavenging, the leading air can be sucked into the upper side of the scavenging passage, and at the time of scavenging, the leading air scavenges the combustion gas in the cylinder first, so that the mixture does not easily flow out. Therefore, fuel efficiency is improved and a complicated muffler structure is not required.

On the other hand, not only a stratified scavenging two-cycle engine but also a normal engine generally operates idling in a lean mixture state. However, in the case of a stratified scavenging two-cycle engine, if rapid acceleration is performed from an idling state, the leading air from the scavenging passage is first supplied into the cylinder, so that a mixture with a sufficient fuel ratio is not supplied, The lean mixture vaporization is further advanced, resulting in poor acceleration or engine stoppage.
As a countermeasure technique, it has been proposed to install an acceleration device that temporarily increases the amount of fuel during acceleration (for example, Patent Document 1).

  The acceleration device of Patent Document 1 includes a carburetor, an insulator provided between the carburetor and the engine to suppress heat transfer from the engine, and an acceleration pump connected to the carburetor, an insulator leading air passage of the insulator, an acceleration pump, This is a structure in which

JP 2001-123841

  However, in the acceleration device described in Patent Document 1, since the acceleration pump is provided apart from the insulator and the carburetor, it is necessary to secure an installation space for the acceleration pump separately from the insulator and the carburetor. There is a problem of taking. In addition, since the acceleration pump and the insulator are connected by piping, there is a problem that the communication structure by the piping becomes complicated when the acceleration pump is arranged at a position far away from the insulator and the carburetor.

  An object of the present invention is to provide an insulator capable of simplifying the communication structure and realizing space saving around the engine.

  An insulator according to claim 1 of the present invention is an insulator provided between an engine and a carburetor and having a heat insulating portion having an insulator leading air passage and an insulator mixed gas passage, and a housing formed integrally with the heat insulating portion. And the housing part constitutes a part of the housing of the acceleration pump.

  According to the first aspect of the present invention, the housing part formed integrally with the heat insulating part constitutes a part of the housing of the acceleration pump, so that the acceleration pump is arranged around the insulator which was a dead space in the past. This saves space by eliminating the installation space dedicated to the acceleration pump. In addition, since the acceleration pump is arranged directly around the heat insulating portion, even when piping is used to connect the insulator leading air passage and the acceleration pump, the length of the piping can be shortened, and the communication structure can be simplified. it can. Further, since the housing part is formed integrally with the heat insulating part, the number of parts can be reduced, the cost can be reduced, and the acceleration pump can be easily assembled.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 is a cross-sectional view showing a structure around an insulator 2 according to the present embodiment, FIG. 2 is a cross-sectional view of the insulator 2 viewed from the carburetor 3 side, and FIG. 3 is an exploded perspective view of the acceleration pump 6.

  As shown in FIG. 1, a stratified scavenging two-cycle engine 1 to which an insulator 2 is attached includes an engine leading air passage 11 that communicates with the scavenging passage, and an engine mixture passage 12 that communicates with the crank chamber. In the stroke, the leading air and the air-fuel mixture are sucked through the passages 11 and 12. A carburetor 3 is attached to such an engine 1 via an insulator 2.

  The carburetor 3 is provided with a cab leading air passage 31 on the upper side, a cab air-fuel mixture passage 32 on the lower side, and a constant pressure fuel supply mechanism 4 for supplying fuel to the cab air-fuel mixture passage 32 at the bottom. The constant pressure fuel supply mechanism 4 includes an internal flow that communicates a carburetor constant pressure chamber 41 defined on the lower side with a diaphragm 40 therebetween, a constant pressure fuel chamber 42 defined on the upper side, a fuel tank (not shown), and the constant pressure fuel chamber 42. A path 43 and a fuel pump 44 provided in the middle of the internal flow path 43 are included.

  The carburetor constant pressure chamber 41 communicates with the atmosphere through the communication path 410. The constant pressure fuel chamber 42 includes a needle valve 421 that opens and closes a communication hole 420 that allows the internal flow path 43 and the constant pressure fuel chamber 42 to communicate with each other, and supplies fuel from the fuel supply passage 422 to the cab mixture passage 32. The fuel pump 44 moves the diaphragm 45 up and down by the pulsation pressure in the crank chamber transmitted from the engine 1. That is, when fuel is supplied from the constant pressure fuel chamber 42 to the cab mixture passage 32 through the fuel supply passage 422, the communication hole 420 is opened by the needle valve 421, and the fuel pump 44 moves the diaphragm 45 up and down to thereby move the fuel. Is sucked out of the fuel tank and supplied to the constant pressure fuel chamber 42.

  The insulator 2 is a synthetic resin member that suppresses heat transfer from the engine 1 to the carburetor 3, and includes a heat insulating part 20 for suppressing heat transfer, and a housing formed integrally with the heat insulating part 20 below the heat insulating part 20. Part 5.

  The heat insulating portion 20 includes an insulator leading air passage 21 that allows the engine leading air passage 11 and the cab leading air passage 31 to communicate with each other, and an insulator mixed air passage 22 that allows the engine mixture passage 12 and the cab air mixture passage 32 to communicate with each other. Yes. As shown in FIG. 2, a pulsation transmission passage 23 is provided below the insulator mixture passage 22. One end of the pulsation transmission passage 23 communicates with the crank chamber of the engine 1, and the other end communicates with the fuel pump 44 of the carburetor 3 to transmit the pulsation pressure in the crank chamber to the fuel pump 44. Further, the heat insulating portion 20 is provided with a first passage 24 that extends laterally (right side in FIG. 2) from the insulator leading air passage 21. The first passage 24 communicates with a pipe 71 configured by a pipe 25 attached to the heat insulating part 20, a pipe 52 attached to the housing part 5, and a tube 70 connecting the pipes 25, 52.

  As shown in FIG. 3, first connecting holes 26 </ b> A to 26 </ b> D are formed in corner portions of the heat insulating portion 20. A nut 27 is embedded between the connection holes 26A and 26B and between the connection holes 26C and 26D. Second connecting holes 28A and 28B are formed at positions corresponding to the nuts 27. The insulator 2 is attached to the engine 1 by screwing screws (not shown) inserted into the first connection holes 26 </ b> A to 26 </ b> D into screw holes on the engine 1 side. The carburetor 3 is attached to the insulator 2 by screwing a screw that penetrates the carburetor 3 and the second connection hole into the nut 27.

  The acceleration pump 6 includes a housing 60 that is formed in a funnel shape, a diaphragm 60 that is supported by a support portion 50 that is formed in a bowl shape on the inner peripheral surface of the housing portion 5, and a bump that protrudes from the bottom of the housing portion 5. A spring 61 fitted between the provided spring guide part 51 and installed between the housing part 5 and the diaphragm 60, and a lid 63 fitted into the housing part 5 and sandwiching the packing 62 and sandwiching the support part 50 and the diaphragm 60. It is comprised including.

Here, in this embodiment, the housing 64 of the acceleration pump 6 is comprised from the housing part 5 and the lid | cover 63. FIG. Further, as shown in FIG. 1, of the space inside the housing 64,
A negative pressure chamber 65 is formed by a space partitioned by the diaphragm 60 and accommodating the spring 61,
A pump chamber 66 is formed by the space on the lid 63 side.

  The base 53 of the housing part 5 is provided with a second passage 54 (see FIG. 2) communicating with the pipe 71. The pressure introduction passage 7 is formed by the first passage 24, the second passage 54, and the pipe 71, and the negative pressure in the insulator leading air passage 21 is transmitted to the negative pressure chamber 65 through the pressure introduction passage 7.

  The lid 63 is provided with an insertion port 67. A protrusion 46 protruding from the carburetor 3 is inserted into the insertion port 67. The pump chamber 66 communicates with the carburetor constant pressure chamber 41 through a communication path 68 formed in the back of the insertion port 67 and a communication path 460 provided in the protrusion 46.

  Therefore, in this embodiment, since the housing part 5 constitutes a part of the housing 64 of the acceleration pump 6, the acceleration pump 6 is located below the heat insulating part 20 and in the space between the engine 1 and the carburetor 3. This space is conventionally a dead space where nothing is placed. For this reason, in the present embodiment, it can be said that the acceleration pump 6 is provided by effectively using such dead space, and space saving can be realized.

  In addition, since the housing part 5 is formed integrally with the heat insulating part 20, the number of parts can be reduced, the cost can be reduced, and the assembly can be facilitated. Furthermore, since the acceleration pump 6 is disposed directly below the heat insulating portion 20, the length of the pipe 71 that allows the insulator leading air passage 21 and the negative pressure chamber 65 in the acceleration pump 6 to communicate with each other can be shortened, and the communication structure Can be easy.

  Further, in the conventional acceleration pump as described in the background art, a partition wall forming member is provided inside the housing, and a guide portion for guiding a spring is provided in the partition wall forming member. However, in this embodiment, since the spring guide portion 51 for guiding the spring 61 is provided integrally with the housing portion 5 so that the partition forming member is not required, the number of parts can be further reduced, and the partition forming member can be reduced. Therefore, the space in the housing 64 can be reduced by the amount that is not required, and the acceleration pump 6 can be reduced in size.

The above carburetor 3 and insulator 2 operate as follows.
First, during idling, the cab leading air passage 31 is closed in conjunction with the throttle valve in the cab air-fuel mixture passage 32, so that the inside of each leading air passage 11, 21, 31 is negative due to the intake operation on the engine 1 side. Pressure. Therefore, negative pressure is introduced from the insulator leading air passage 21 into the negative pressure chamber 65 through the pressure introduction passage 7, and the diaphragm 60 is pulled toward the negative pressure chamber 65 against the spring force of the spring 61. However, since the throttle valve opens when the engine 1 is accelerated, the insulator leading air passage 21 is also opened in conjunction with this, and the negative pressure disappears all at once.

  Thus, the diaphragm 60 is instantaneously returned to the pump chamber 66 side by the spring force of the spring 59, and the air in the pump chamber 66 is pumped to the carburetor constant pressure chamber 41 through the communication passages 68 and 460. Therefore, the diaphragm 40 that partitions the constant pressure fuel chamber 42 and the carburetor constant pressure chamber 41 is pushed up, and the fuel in the constant pressure fuel chamber 42 is pressurized, so that the amount of fuel supplied to the cab mixture passage 32 increases. Accordingly, during rapid acceleration, the fuel supply amount is temporarily increased by the acceleration pump 6, so that the engine 1 can be smoothly accelerated even during rapid acceleration. At this time, since the inner diameter of the communication passage 410 that communicates the carburetor constant pressure chamber 41 and the atmosphere is smaller than the inner diameter of the communication passages 68 and 460 from the acceleration pump 6 side, the carburetor is compressed by the air fed from the communication passages 68 and 460. It is possible to reliably push up the diaphragm 40 on the constant pressure chamber 41.

The best configuration, method, and the like for carrying out the present invention have been disclosed above, but the present invention is not limited to this. That is, the invention has been illustrated and described primarily with respect to particular embodiments, but may be configured for the above-described embodiments without departing from the scope and spirit of the invention. Various modifications can be made by those skilled in the art in terms of quantity, other details, and the like.
Therefore, the description limited to the shape, quantity and the like disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which remove | excluded the limitation of one part or all of such restrictions is included in this invention.

  For example, the pressure introduction passage 7 that communicates the insulator leading air passage 21 and the negative pressure chamber 65 may not include the pipe 71, and a groove provided on the connection surface of the heat insulating portion 20 with the engine 1 A passage provided in the heat insulating portion 20 to communicate the insulator leading air passage 21 and the groove, and a passage provided in the heat insulating portion 20 and the housing portion 5 to communicate the negative pressure chamber 65 and the groove. May be. In this case, the piping 71 provided outside can be made unnecessary, the communication structure can be simplified, and space saving can be promoted. Further, the pressure introduction passage 7 may be configured to include a groove provided on a connection surface of the heat insulating portion 20 with the carburetor 3.

  In the acceleration pump 6 of the present embodiment, the spring guide portion 51 is integrally formed in the housing 64. However, a partition wall forming member as shown in Patent Document 1 described in the background art is provided in the housing 64. One end of the spring 61 may be supported by providing the partition wall forming member with the spring guide portion 51.

  INDUSTRIAL APPLICABILITY The present invention can be used in portable work machines such as blowers and brush cutters as an accelerator pump-integrated insulator provided between a stratified scavenging two-cycle engine and a carburetor.

Sectional drawing which shows the structure around the insulator which concerns on one Embodiment of this invention. Sectional drawing of the insulator seen from the carburetor side. The exploded perspective view of an acceleration pump.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Insulator, 3 ... Carburetor, 5 ... Housing part, 6 ... Acceleration pump, 20 ... Thermal insulation part, 21 ... Insulator lead air path, 22 ... Insulator mixed gas path, 64 ... Housing.

Claims (1)

In the insulator,
A heat insulating portion provided between the engine and the carburetor and having an insulator leading air passage and an insulator mixture passage;
A housing part formed integrally with the heat insulating part,
The insulator is characterized in that the housing part constitutes a part of a housing of an acceleration pump.

Images