JP2007071054A - Insulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulator which simplifies a communicating structure and realizes space saving around an engine. <P>SOLUTION: In an insulator 30, an accelerating pump mounting part 51 is provided to the lower part of a thermal insulation part 31. An acceleration pump 50 is mounted in the accelerating pump mounting part 51. A passage 41 is formed in the lower part of the thermal insulation part 31. A groove 42 for connecting an insulator air passage 32 and the passage 41 is formed in the connection surface 43 with the engine 1. A connection passage 61 for connecting the passage 41 and a negative pressure introduction chamber 70 is provided to an upper part of the acceleration pump 50. By so doing, the acceleration pump 50 can be easily arranged in a lower place of the insulator 30 which is originally a dead space. The need for external piping for communicating between the insulator 30 and acceleration pump 50 can be eliminated. Besides materializing space saving, as a result, a communicating structure can be simplified. <P>COPYRIGHT: (C)2007,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 an air passage communicating with the scavenging passage. Thus, prior to scavenging, air can be supplied to the upper side of the scavenging passage. During scavenging, the air scavenges the combustion gas in the cylinder first, so that the air-fuel mixture hardly flows 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 air from the air passage is first supplied into the cylinder, so that a mixture with a sufficient fuel ratio is not supplied and lean mixing is performed. Vaporization is further advanced and acceleration failure or engine stop occurs.
As a countermeasure technique, it has been proposed to install an acceleration device that temporarily increases the fuel amount 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, an acceleration pump connected to the carburetor, and an air passage of the insulator and the acceleration pump. It is a structure that communicates with piping.

JP 2001-123841 A (pages 2 to 4)

  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. 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 provided between an engine and a carburetor, and has a heat insulating portion having an insulator air passage and an insulator mixture passage, and is integrally formed with the heat insulating portion, and an acceleration pump is attached thereto. And an acceleration pump mounting portion.

  The insulator according to claim 2 of the present invention is the insulator according to claim 1, wherein a negative pressure introducing chamber of an acceleration pump attached to the acceleration pump mounting portion is provided on a connection surface of the heat insulating portion with the engine or the carburetor. And a groove for a pressure introduction passage that communicates with the insulator air passage of the heat insulating portion.

  According to the first aspect of the present invention, since the acceleration pump mounting portion is provided integrally with the heat insulating portion, the acceleration pump is mounted on the acceleration pump mounting portion, so that the acceleration pump is provided around the insulator which has been a dead space in the past. Can be arranged well, and it is not necessary to provide a separate installation space dedicated to the acceleration pump, and space saving can be realized. Moreover, even when piping is used to connect the air passage of the insulator and the negative pressure introduction chamber, the length of the piping can be very short because the acceleration pump can be mounted directly around the heat insulating part, and the communication structure is simple. Can be.

  According to the invention of claim 2, the insulator air passage and the negative pressure introduction chamber communicate with each other through a pressure introduction passage formed in the chamber, and the pressure introduction passage includes a groove on a connection surface with the engine or the carburetor. Since it is formed, conventional external piping can be eliminated and the communication structure can be further simplified. In addition, such a groove | channel is plugged by the connection surface of an engine or a carburetor, and becomes a tubular shape.

[First Embodiment]
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings.
1 is a side sectional view showing a structure around an insulator 30 according to the present embodiment, FIG. 2 is an exploded perspective view of the insulator 30, and FIG. 3 is a rear view of the insulator 30.

  The stratified scavenging two-cycle engine 1 to which the insulator 30 is attached includes an air passage 2 and an air-fuel mixture passage 3 provided on the intake side (FIG. 3), and scavenging air is passed through the passages 2 and 3 in the intake stroke. And suck the mixture. A carburetor 20 is attached to such an engine 1 via an insulator 30 as shown in FIG. 1, and an air cleaner 10 containing a filter element (not shown) is attached to the carburetor 20.

  The air cleaner 10 is provided with an intake port 11, and an insertion port 12 is provided below the intake port 11. A grommet 13 is attached to the insertion opening 12, and a protrusion 25 protruding from the carburetor 20 is inserted into the grommet 13. The scavenging air and air that is the basis of the air-fuel mixture sent to the engine 1 are first sucked from the intake port 11 and sent to the carburetor 20.

  The carburetor 20 is provided with a cab air passage 21 on the upper side, a cab mixture passage 22 on the lower side, and a constant pressure fuel supply mechanism at the bottom. The constant pressure fuel supply mechanism includes a constant pressure fuel chamber defined on the upper side across a first film (not shown) and a carburetor constant pressure chamber 24 defined on the lower side. The carburetor constant pressure chamber 24 communicates with the air cleaner 10 side (atmosphere side) through a communication passage 250 provided in the protrusion 25, and the constant pressure fuel chamber communicates with the cab mixture passage 22. A fuel pump or the like is formed on the upper part of the constant pressure fuel chamber by the second film. The second membrane moves up and down by the pulsation pressure of the crank chamber transmitted from the engine 1, whereby the fuel in the fuel tank is supplied to the constant pressure fuel chamber.

  During normal operation of the engine 1, the fuel in the constant pressure fuel chamber is sucked out of the constant pressure fuel chamber into the cab mixture passage 22 by the negative pressure generated in the cab mixture passage 22. Part of the air sucked from the intake port 11 flows into the cab air passage 21 and is sent to the insulator 30, and the remaining air flows into the cab mixture passage 22 and then sucked out from the constant pressure fuel chamber. The fuel is mixed with the fuel and sent to the insulator 30 as an air-fuel mixture.

  The insulator 30 is a synthetic resin member that suppresses heat transfer from the engine 1 to the carburetor 20. In this embodiment, the insulator 30 for suppressing heat transfer and the acceleration pump 50 are provided below the heat insulator 31. A frame-like acceleration pump mounting portion 51 to be mounted is integrally provided. That is, in the present embodiment, the acceleration pump 50 is attached to such an acceleration pump attachment portion 51, whereby the acceleration pump 50 is disposed below the heat insulating portion 31 and in the space between the engine 1 and the carburetor 20. In the past, this space was a dead space where nothing was placed. Therefore, in this embodiment, it can be said that the acceleration pump 50 is provided by effectively using such dead space, and space saving can be realized.

  The heat insulating portion 31 includes an insulator air passage 32 that communicates the cab air passage 21 and the air passage 2 on the engine 1 side, and an insulator air mixture passage 33 that communicates the cab mixture passage 22 and the mixture passage 3 on the engine 1 side. A pulsation transmission passage 34 is provided below the insulator mixture passage 33. One end of the pulsation transmission passage 34 communicates with the crank chamber of the engine 1 and the other end communicates with the constant pressure fuel supply mechanism to transmit the pulsation pressure in the crank chamber to the constant pressure fuel supply mechanism. Moreover, a pair of connection holes 35 are provided in such a heat insulating portion 31. A nut 36 is embedded in the back side of the connecting hole 35. A screw (not shown) that passes through the air cleaner 10 and the carburetor 20 is inserted into the coupling hole 35, and the air cleaner 10 and the carburetor 20 are attached to the insulator 30 by screwing the screw into the nut 36.

  The heat insulating portion 31 is provided with a passage 41 that penetrates the lower side in the lateral direction (left-right direction in FIG. 1). A groove 42 connecting the insulator air passage 32 and the passage 41 is formed in the connection surface 43 of the heat insulating portion 31 with the engine 1.

  As shown in FIG. 2, the acceleration pump 50 includes a plate 52 attached to the engine 1 side of the acceleration pump attachment portion 51, a first case 55 attached to the carburetor 20 side of the acceleration pump attachment portion 51, and a first case. And a second case 58 that covers 55, and these are assembled together by a screw 64. Further, a gasket 53 is interposed between the acceleration pump mounting portion 51 and the first case 55, and a diaphragm 56 and a gasket 57 are interposed between the first case 55 and the second case 58. Further, the first case 55 is provided with a support wall 54, and a spring 59 is disposed between the support wall 54 and the diaphragm 56.

  A space defined by the acceleration pump mounting portion 51, the plate 52, the gasket 53, and the support wall 54 of the first case 55 is defined as a negative pressure introduction chamber 70, and is defined by the support wall 54 and the diaphragm 56 of the first case 55. A space defined by the diaphragm 56, the gasket 57, and the second case 58 is a pump chamber 72. Further, the negative pressure introducing chamber 70 and the negative pressure chamber 71 communicate with each other through a communication hole 73. That is, it can be said that the acceleration pump mounting portion 51 in this embodiment forms the negative pressure introduction chamber 70 of the acceleration pump 50, and constitutes a part of the acceleration pump 50.

  At the upper part of the first case, a connection portion 60 is provided at a position where it does not interfere with the pulsation transmission passage 34. The connection portion 60 protrudes upward from the first case 55 and is provided so as to abut on the vicinity of the passage 41 provided in the lower portion of the heat insulating portion 31. The connecting portion 60 is provided with a groove-like connecting passage 61 that connects the passage 41 of the heat insulating portion 31 and the negative pressure introducing chamber 70 in communication. The second case 58 is provided with an insertion port 62. A grommet 63 is attached to the insertion port 62, and a protrusion 23 projecting from the carburetor 20 is inserted into the grommet 63. The pump chamber 72 communicates with the carburetor constant pressure chamber 24 through a communication passage 230 provided inside the protrusion 23.

  In such a heat insulating portion 31 and the acceleration pump 50, the groove 42 provided in the connection surface 43 of the heat insulating portion 31 is closed by the engine 1 to be tubular, and is similarly provided in the first case of the acceleration pump 50. Since the connecting passage 61 is also closed by the side surface of the acceleration pump mounting portion 51 and becomes tubular, the insulator air passage 32 and the negative pressure introduction chamber 70 are connected in communication, and the negative pressure in the insulator air passage 32 is introduced into the negative pressure. It is introduced into the chamber 70 and eventually into the negative pressure chamber 71. Therefore, there is no need for conventional external piping for communicating the insulator and the acceleration pump, the communication structure can be simplified, and the assembly can be facilitated. The groove 42, the passage 41, and the connection passage 61 constitute a pressure introduction passage 80 according to the present invention.

Further, the above carburetor 20 and insulator 30 operate as follows.
First, during idling, the cab air passage 21 is closed in conjunction with the throttle valve in the cab air-fuel mixture passage 22, so that the air passages 2, 21, and 32 are at negative pressure. Therefore, a negative pressure is introduced from the insulator air passage 32 through the pressure introduction passage 80 into the negative pressure introduction chamber 70, and the diaphragm 56 is pulled toward the negative pressure chamber 71 against the spring force of the spring 59. However, since the throttle valve is opened when the engine 1 is accelerated, the insulator air passage 32 is also opened in conjunction with this, and the negative pressure disappears all at once.

  As a result, the diaphragm 56 is instantaneously returned to the pump chamber 72 side by the spring force of the spring 59, and the air in the pump chamber 72 is pumped to the carburetor constant pressure chamber 24 through the communication passage 230. For this reason, the first film partitioning the constant pressure fuel chamber and the carburetor constant pressure chamber 24 is pushed up, and the fuel in the constant pressure fuel chamber is pressurized, so that the amount of fuel supplied to the cab mixture passage 22 increases. Accordingly, during rapid acceleration, the fuel supply amount is temporarily increased by the acceleration pump 50, so that the engine 1 can be smoothly accelerated even during rapid acceleration. At this time, the inner diameter of the communication passage 250 connected to the carburetor constant pressure chamber 24 is smaller than the inner diameter of the communication passage 230 from the acceleration pump 50 side. It is possible to push up the film of 1 reliably.

[Second Embodiment]
FIG. 4 is a partially omitted side sectional view showing the structure around the insulator 30 according to the second embodiment of the present invention. In the present embodiment, the same members and the same functional parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified here. The same applies to the third embodiment described below.

Unlike the first embodiment, the present embodiment is characterized in that the acceleration pump mounting portion 51 does not constitute a part of the acceleration pump 50.
The acceleration pump mounting portion 51 is provided so as to protrude below the heat insulating portion 31, and the acceleration pump 50 is mounted by a screw or the like. Under the present circumstances, the channel | path 41 is provided in the heat insulation part 31 lower part, passes through the acceleration pump attachment part 51, and is connected with the connection channel | path 61 provided in the acceleration pump 50.

Also in this embodiment, the acceleration pump mounting portion 51 is provided integrally with the heat insulating portion 31, and the acceleration pump 50 is mounted on the acceleration pump mounting portion 51. Accordingly, the acceleration pump 50 is disposed below the heat insulating portion 31, and the pressure introduction passage 80 connects the insulator air passage 32 and the negative pressure introduction chamber 70 in communication with each other. The same effect as the embodiment can be obtained, the installation space for the acceleration pump and the external piping are not required, the space can be saved, and the communication structure can be simplified.
In particular, in the present embodiment, the acceleration pump mounting portion 51 does not constitute a part of the acceleration pump 50, so that the structure of the insulator 30 can be simplified.

[Third Embodiment]
FIG. 5 shows a third embodiment of the present invention.
In the present embodiment, the acceleration pump mounting portion 51 is provided on the front and rear of the lower portion of the heat insulating portion 31 (both sides in the left-right direction in FIG. 5), and does not constitute a part of the acceleration pump 50, The passage 41 is characterized in that it does not pass through the acceleration pump mounting portion 51 and is connected to the connection passage 61 in the connection portion 60 provided in the acceleration pump 50.
In this embodiment as well, the same function and effect can be obtained with the same configuration as in the first and second embodiments described above.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, the groove 42 of the insulator 30 may be formed on the connection surface with the carburetor 20 of the heat insulating portion 31 to constitute the negative pressure introduction passage 80.
Further, the insulator air passage 32 and the negative pressure introduction chamber 70 may not be communicated by the negative pressure introduction passage 80 formed including the groove 42, but may be communicated by piping. Even in this case, since the acceleration pump 50 is disposed at a position close to the periphery of the heat insulating portion 31, the length of the pipe may be very short, and the communication structure can be simplified.

  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.

The sectional side view which shows the structure around the insulator which concerns on 1st Embodiment of this invention. The disassembled perspective view of the insulator. The rear view of the said insulator. The sectional side view which abbreviate | omits and shows the structure around the insulator which concerns on 2nd Embodiment of this invention. The sectional side view which abbreviate | omits and shows the structure around the insulator which concerns on 3rd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 20 ... Carburetor, 30 ... Insulator, 31 ... Heat insulation part, 32 ... Insulator air passage, 33 ... Insulator air passage, 41 ... Passage, 42 ... Groove, 50 ... Acceleration pump, 51 ... Acceleration pump attachment part, 61 ... Connection passage, 80 ... Pressure introduction passage.

Claims (2)

A heat insulating portion provided between the engine and the carburetor and having an insulator air passage and an insulator mixture passage;
An insulator having an acceleration pump mounting portion that is integrally formed with the heat insulating portion and to which the acceleration pump is mounted. Insulator according to claim 1,
A groove for a pressure introduction passage that connects a negative pressure introduction chamber of an acceleration pump attached to the acceleration pump attachment portion and an insulator air passage of the insulation portion on a connection surface of the heat insulation portion with the engine or the carburetor. An insulator characterized in that is formed.

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