Patent Application
20180252185
The embodiments disclosed herein concern a device for adjusting the adjustment valve in a carburetor having a fuel adjustment function which can adjust the fuel flow by hand in a carburetor which is suitable for feeding fuel to general-purpose engines used for motive power, such as agricultural or gardening machinery, etc.
Carburetors which feed fuel to general-purpose engines feed very small fuel flow quantities, compared with carburetors which feed fuel to four-cycle engines, such as automobile engines, and there are great change ratios in the fuel flow quantity, which depend on deviations in the positions or dimensions of various parts or differences in the quality of the parts. In addition, there are differences in the performances of the engines to which the fuel is fed. Therefore, the fuel flow quantity must be adjusted individually.
Therefore, manual adjustment valves, which are made so that the fuel flow quantities can be adjusted individually, are placed in the main fuel path and the low-speed fuel path. These adjustment valves consist of a needle-shaped valve body which is inserted in the fuel path and continuously changes its effective area, a screw part which is joined with the main body of the carburetor by screwing and can be moved forward and backward while this valve body is rotated, and a head part, which is exposed outside of the main carburetor body and has the purpose of rotating the screw part.
These adjustment valves are supplied to general users in a state in which the adjustment operations are fundamentally performed by the manufacturers of the carburetors and the engines or the machinery in which they are assembled, and they are adjusted to the optimum fuel flow quantities. However, the valves may be operated in cases in which the users think that the performances of the engines need to be maintained in response to changes in the places or conditions in which the users use them, for example, changes in air pressure, or they think that temporary malfunctions in the engines need to be corrected or their performances improved. As a result of the carburetor being adjusted outside its range of adjustment and the air-fuel mixture being made too lean or too rich, troubles such as a reduction of output, a worsening of the state of the exhaust, and engine stoppage can be produced.
On the other hand, exhaust regulations are now being imposed even on general-purpose engines; therefore, the adjustment valves which manufacturers have adjusted within ranges which conform to these exhaust regulations are required to have adjustment devices which impose means of limitation in such a way that users cannot adjust them outside these conformance ranges.
As an adjustment device which has a means of limitation such that the adjustment valves in such carburetors cannot be operated above a certain point, Japanese Patent No. Showa 47-42424 (Patent Reference 1), for example, discloses a limit cap which has an arm which projects in a radial direction and is installed on the head of the adjustment valve; the valve can only be operated within one rotation due to its touching the main carburetor body, which is a stopper.
Moreover, in Japanese Unexamined Patent Application No. Showa 61-134555 (Patent Reference 2), for example, an adjustment device is disclosed in which the adjustment valves in the main fuel path and the low-speed fuel path are placed close to and parallel with each other, and they can be only operated within one rotation due to an arm on each one touching the other adjustment valve, which is a stopper, or a limit cap.
In these conventional adjustment devices, the limit caps are temporarily fitted to such a degree that they do not drop off the head before the manufacturer adjusts them, and the main fitting is done in a position such that the arm touches the stopper when the adjustment is finished, or they are fitted in a position in which the arm touches the stopper after the manufacturer's adjustment, without a temporary fitting.
However, the limit caps which are a means of limiting these rotations are exposed to the outside of the main carburetor body. Therefore, they have the problems that they are easily removed by intentional vandalism of the users, or the adjustments may slip due to the user unintentionally touching the device during the adjustment.
Therefore, for example, in the pilot screw (adjustment valve) adjustment device for carburetors which is shown in Japanese Utility Model No. Heisei 6-40339 (Patent Reference 3), as shown in
By rotating the adjustment tool inserted into the tool insertion groove 11a, the adjustment valve 1a is rotated, and the effective opening area of the fuel flow path is variably adjusted by rotating the adjustment valve 1a. Thus, the rotation of the adjustment valve 1a is limited to a specific adjustment range by the fact that the side surface of a semicircular flange part touches the locking part 42a of the regulating member 4a.
In the adjustment device of this adjustment valve, the adjustment valve 1a and the regulating member 4a are disposed in a sleeve 5a. In a carburetor which has a regulating valve of the fuel flow quantity and a control means for this regulating valve, it can be made difficult to remove the device by the user's intentional vandalism performed on the aforementioned regulating member which is disposed in this sleeve.
However, the adjustment device of the adjustment valve in this carburetor uses a flat-plate-shaped regulating member as the means of control, and the regulating member limits removal by being inserted into and fixed in a storage hole. However, since it is formed as a flat plate, it must be pressed in or fastened, or, for example, fixed by using a separate means of fixing, such as a screw, when it is pressed into and fixed in the storage hole.
Therefore, it is difficult to make the limit cap small and the parts are costly. Furthermore, it has problems in its operation, namely, that it is hard to make it difficult for users to remove it, and it is easily removed during adjustment, etc.
Documents of the Related Art
The problem this embodiment addressed herein is to provide an adjustment device of the adjustment valves in carburetors which is provided with a small, inexpensive limit cap which can be easily assembled without increasing the number of parts and which prevents the user's intentional and forceful removal by over-operation or destruction, and can solve the problems in the operations of manufacturers and users.
The embodiment disclosed herein to solve the problem mentioned above is an adjustment device of adjustment valves in carburetors which adjust the effective area of the fuel path by being screwed into an adjustment hole which communicates with the fuel path formed in the main carburetor body. This adjustment of the effective area of the fuel path is performed by moving the device in the axial direction by rotating it by a tool insertion groove which is formed in a head of the adjustment valve. The adjustment device includes a tubular limit cap and a sleeve. The limit cap has an insertion hole which allows the adjustment valve to be rotatably inserted into the center of the tip surface of the limit cap, as well as flange-shaped engaging and protruding pieces in the insertion hole which engage with engaging grooves formed in a shaft part of the adjustment valve and limit the adjustment valve to a specific range of rotation. A circumferential locking part is formed having a knurling which extends in the longitudinal direction on the circumferential surface of the limit cap and the sleeve. An inner circumferential locking part formed in the bottom of the inner circumferential surface of the sleeve engages with and locks with the outer circumferential engaging part of the aforementioned limit cap. The aforementioned adjustment valve and the aforementioned limit cap are inserted movably in the axial direction in the sleeve. The aforementioned engaging grooves include two engaging grooves, a first and a second engaging groove, which are formed in specific axial positions along the length of the aforementioned shaft part from the base end to the tip end. In addition, the aforementioned engaging and protruding pieces formed in the insertion hole of the limit cap engage with the aforementioned first engaging groove and keep the limit cap in an axial position such that the aforementioned outer circumference locking part does not lock with the inner circumference locking part of the aforementioned sleeve. These comprise a first engaging and protruding piece which keeps the limiting cap in a first step position, in which it can move freely in the circumferential direction, and a second engaging and protruding piece which engages with the aforementioned second engaging groove when the limit cap has been pressed in the lower direction from the aforementioned first step position, locks the outer circumference locking part of the limit cap with the inner circumferential locking part of the sleeve, obstructs its rotation, and limits the range of rotation of the adjustment valve in the aforementioned insertion hole to a previously set range.
By means of this embodiment, the aforementioned first engaging and protruding piece which was formed in the insertion hole of the limit cap engages with the first engaging groove of the adjustment valve and keeps the limit cap in the adjustment valve in a position such that the outer circumference locking part of the limit cap comes to be in an axial position in which it is not locked to the inner circumference locking part in the sleeve. That is, in the first step position, in which the rotation of the limit cap in the sleeve is in a free state, it is adjusted by the manufacturer to an optimal position in the range which conforms to the exhaust regulations. Furthermore, the device is shipped with the limit cap disposed in the second step position, in which the limit cap has been pushed in, the outer circumference locking part of the limit cap is locked into the inner circumference locking part of the sleeve, and the rotation of the limit cap in the sleeve is limited, and the second engaging and protruding piece is engaged in the second engaging groove formed in the shaft of the adjustment valve. The rotation of the aforementioned adjustment valve, which is engaged in the second engaging groove which was formed in the shaft of the adjustment valve, is limited to a specific angle. If necessary, the user can make an adjustment by rotating the adjustment valve in the angular range which is in the aforementioned second step position.
In this embodiment, moreover, the part of the aforementioned adjustment valve which is inserted into the insertion hole of the aforementioned limit cap has a semicircular rod shape. The part of the aforementioned adjustment valve which is inserted into the insertion hole of the limit cap has an arc-shaped horizontal cross section, and the insertion hole formed in the aforementioned limit cap has an arc-shaped insertion hole part into which the inserted part of the aforementioned adjustment valve is inserted, and an arc-shaped movement hole part connected and coaxial with the insertion hole part and has the same diameter. The first engaging and protruding piece which engages with the first engaging groove which is formed in the aforementioned adjustment valve protrudes into the arc-shaped part of the aforementioned insertion hole part, and the second engaging and protruding part which engages with the second engaging groove which is formed in the aforementioned adjustment valve protrudes into the arc-shaped part of the aforementioned movement hole part. The range of rotation of the aforementioned adjustment valve can be limited by forming a stopper in one end, or stoppers in both ends, of the aforementioned insertion hole part and movement hole part.
Moreover, in another embodiment, in the part inserted into the limit cap, from the head of the aforementioned adjustment valve to the second engaging groove, the horizontal cross section in the axial direction presents the shape of an approximately oval horizontal cross section, with arcs formed in both ends of the horizontal direction and approximately equal to the diameter of the insertion hole which is formed in the tip surface of the limit cap. The limit cap presents an insertion hole with the same oval shape as the oval shape which is the horizontal cross section of the adjustment valve which was formed in the shaft and coaxial with it. Due to the fact that it is inserted with the aforementioned adjustment valve, the first engaging and protruding piece which has a protruding piece shape engages with the first engaging groove in order to temporarily fix the aforementioned limit cap and prevent it from easily falling off; the first engaging and protruding piece protrudes into the arc parts on both sides of the aforementioned insertion hole. The movement hole of the limit cap is formed by the second engaging and protruding piece, which engages with a pair of second engagement grooves which are disposed in symmetrical positions, forming an oval-shaped insertion hole which engages with the second engaging groove of the aforementioned adjustment valve. The range of rotation of the aforementioned adjustment valve can also be limited by forming a stopper on the back side of the aforementioned second engaging and protruding piece.
Furthermore, in this embodiment, the aforementioned first engaging and protruding piece and second engaging and protruding piece, which are formed on the aforementioned limit cap, are formed in axial positions close to each other; in the aforementioned second-step position, the aforementioned first and second engaging protrusion pieces engage with the aforementioned second engaging groove and can exhibit a retaining effect.
Furthermore, in this embodiment, the aforementioned adjustment valve can also be applied to at least one of a high-speed side adjustment valve and a low-speed side adjustment valve which are screwed, respectively, into a high-speed side adjustment hole and a low-speed side adjustment hole placed close to each other in the aforementioned main carburetor body and which communicate with the high-speed side fuel flow path and the low-speed side fuel flow path formed in the aforementioned main carburetor body.
Effect of the Embodiment. By means of this embodiment, in a carburetor which is suitable for feeding fuel to general-purpose engines and has an adjustment valve for the fuel flow quantity and a means for controlling that adjustment valve, not only is the generation of additional parts avoided, the procedure of assembly does not differ greatly from the prior art, and it is made very difficult for the user to remove the aforementioned cap, which is disposed in the aforementioned sleeve in the working embodiments, by intentional vandalism, and the size of the limiting cap can be made smaller and its cost can be reduced.
The details of the example embodiments, including structure and operation, may be gleaned in part by study of the accompanying figures, in which like reference numerals refer to like parts. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles. Moreover, all illustrations are intended to convey concepts, where relative sizes, shapes and other detailed attributes may be illustrated schematically rather than literally or precisely.
It should be noted that the figures are not necessarily drawn to scale and that elements of similar structures or functions are generally represented by like reference numerals for illustrative purposes throughout the figures.
Furthermore, although the high-speed side adjustment valve 4 and the low-speed side adjustment valve 5 differ in the axial lengths of some of their constituent elements, they are the same in function and the high-speed side limit cap 6 and the low-speed side limit cap 7 have the same parts; therefore, this embodiment can be used in the same way in both the high-speed side adjustment valve 4 and the low-speed side adjustment valve 5, and the explanation below will deal with the high-speed side adjustment valve 4 and the high-speed side limit cap 6.
The adjustment device of the adjustment valve 4 in this working embodiment is constituted primarily by the aforementioned adjustment valve 4; a tubular limit cap 6 of the aforementioned adjustment valve 4, which has a tip side and an insertion hole 61 in the center of its tip side and which includes a knurl which extends longitudinally on its circumferential surface and which forms an outer circumference locking part 62; and a sleeve 8, which is placed surrounding the adjustment hole 3 in the aforementioned main carburetor body 2. The aforementioned adjustment valve 4 and the limit cap 6 are inserted movably in the axial direction in the sleeve 8. An inner circumference locking part 81 is formed on the lower part of the inner circumference side and includes a knurl which extends in the longitudinal direction and locks the outer circumference locking part 62 of the aforementioned limit cap 6.
To explain this in more detail, as shown in
On the other hand, as shown in
In this working embodiment, at this time, since the protruding width of the second engaging and protruding piece 64 which was formed in the arc-shaped movement hole part 612, connected to the aforementioned insertion hole part 611, is formed more widely that the protruding width of the first engaging and protruding piece 63 which was formed in the aforementioned arc-shaped insertion hole part 611, this second engaging and protruding piece 64 becomes a stopper on one rotating side, the stopper 65 becomes a stopper on the other rotating side, and the adjustment valve 4 and the limit cap 6, which is free to rotate, rotate as one. Therefore, the manufacturer holds the limit cap 6 at an axial position at which the aforementioned outer circumference locking part 62 does not lock with the inner circumference locking part 81 of the aforementioned sleeve 8, and in this way the aforementioned limit cap 6 is held in the first step position, in which it freely rotates in the circumferential direction without dropping out of the adjustment valve 4, and the adjustment valve 4 is adjusted within a specific adjustment range.
Moreover, as shown next in
In this embodiment, at this time, since the first engaging and protruding piece 63 formed in the insertion hole part 611 of the aforementioned limit cap 6 and the second engaging and protruding piece 64 formed in the movement hole part 612 are formed at almost the same axial position, and the protruding width of the first engaging and protruding piece 63 is formed more narrowly than the second engaging and protruding piece 64, the limit cap 6, which is in the aforementioned first step position, is pushed in until the first engaging and protruding piece 63 engages with the second engaging groove 44 of the adjustment valve. Due to this fact, not only can it be disposed in the second step position, shown in
In the state of this second step position, the shaft 41 of the adjustment valve 4, with a semicircular cross section, is inserted into the 270° arc-shaped insertion hole 61 which is formed by connecting the flat side of the limit cap 6 with the insertion hole part 611 and the movement hole part 612. The adjustment valve 4 can be rotated and adjusted in a 90° range by the user as shown in the drawings, which show the initial state of
Moreover, by changing the positions of the second engaging and protruding piece 64, which engages with the second engaging groove 44 of the adjustment valve 4, and the stopper 65, the adjustment valve 4 is placed in a state in which it can only be rotated in the direction in which the fuel flow quantity is decreased (
Furthermore, the materials forming the aforementioned limit cap tend not to be limited; for example, they can be selected at will from metals, plastics, or other materials.
The main carburetor body 2 and the sleeve 8 in this working embodiment are the same as those of the desirable working embodiment shown in
The aforementioned adjustment valve 4 in this working embodiment has a tool insertion groove 42 formed in the head of the shaft 41; a first engaging groove 43 for preventing the aforementioned limit cap 6 from dropping off, which engages the first engaging and protruding piece 63 of the aforementioned limit cap 6 is formed on the tip end side at the other end from the aforementioned head part; a second engaging groove 44, formed on the tip end side of the aforementioned first engaging groove 43; a screw part 45 which screws into the adjustment hole 3 of the aforementioned main carburetor body 2, which is formed on the tip end side from the aforementioned second engaging groove 44, and which connects them so that they can move in the axial direction; a seal part 46 which is formed on the tip end side from the aforementioned screw part 45 and prevents the fuel from accidently flowing outside from the aforementioned adjustment hole 3; and a needle part 47 which is formed at the tip end for increasing and decreasing the effective area of the fuel flow path and adjusting the fuel flow quantity.
Above all, the horizontal cross section in the axial direction of the part which is inserted into the limit cap 6, from the head of the aforementioned adjustment valve 4 to the second engaging groove 44, presents an approximately oval shape in its horizontal cross section in which arcs approximately equal to the diameter of the insertion hole 61 which is formed on the top surface of the limit cap 6 are formed on both ends in the horizontal direction.
Moreover, as shown in
Moreover, the insertion hole 61 of the limit cap 6 is formed by the second engaging and protruding pieces 64, 64 which engage with a pair of second engaging grooves 44, 44 disposed in symmetrical positions and form an oval-shaped insertion hole 61 which engages with the second engaging groove 44 of the aforementioned adjustment valve 4, and two block-shaped stoppers 65, 65 are placed on the back sides of the aforementioned second engaging and protruding pieces 64, 64.
In this kind of working embodiment, the limit cap 6 is first pushed in until the first engaging and protruding pieces 63, 63 which are formed in arc shapes are pressed and engage with the first engaging grooves 43, 43 which were formed in the shaft 41 of the adjustment valve 4 in the insertion hole 61 of the aforementioned adjustment valve 4. The limit cap 6 is kept in the first step position, an axial position at which the aforementioned outer circumference locking part 62 does not lock with the inner circumference locking part 81 of the aforementioned sleeve 8 and it is made able to rotate freely in the circumferential direction.
In this working embodiment, at this time, since the protruding width of the first engaging and protruding piece 63 which is formed in the arc-shaped part of the aforementioned insertion hole 61 is formed more widely than the protruding widths of the second engaging and protruding pieces 64, 64, these second engaging and protruding pieces 64, 64 become stoppers on both rotating sides and the adjustment valve 4 and the limit cap 6 which rotates freely rotate as one. Therefore, the manufacturer keeps the limit cap 6 at the axial position at which the aforementioned outer circumference locking part 62 does not lock with the inner circumference locking part 81 of the aforementioned sleeve 8, so that the aforementioned limit cap 6 is held in the first step position, at which it can rotate freely in the circumferential direction without dropping from the adjustment valve 4, and the adjustment valve 4 is adjusted in a specific adjustment range.
Moreover, after it is adjusted in the specific adjustment range, the limit cap 6 is pushed down from the aforementioned first step position; the first engaging and protruding pieces 63, 63 formed in the insertion hole 61 of the limit cap 6 are made to escape from the first engaging groove 43 of the aforementioned adjustment valve 4, and when the adjustment valve 4 has been rotated, the second engaging and protruding pieces 64, 64 which form the aforementioned insertion hole 61 can engage the second engaging groove 44. It is put into the second step position, an axial position at which the outer circumference locking part 62 of the limit cap 6 is locked to the inner circumference locking part 81 of the sleeve 8 and rotation is prevented, and the device is shipped.
In this working embodiment, the first engaging and protruding piece 63 and the second engaging and protruding piece 64 which were formed in the insertion hole 61 of the aforementioned limit cap 6 are formed at almost the same axial position, and the protruding width of the first engaging and protruding piece 63 is formed narrower than that of the second engaging and protruding piece 64. Therefore, by pushing the limit cap 1 into the aforementioned first step position until the first engaging and protruding piece 63 engages with the second engaging groove 44 of the adjustment valve 4, not only can it be disposed in the second step position, but a restraining effect is exhibited. Therefore, it is extremely difficult for the user to easily remove the limit cap 6.
In this working embodiment, when the aforementioned adjustment valve 4 is rotated in the circumferential direction in the second step position into which the limit cap 6 was pressed, the aforementioned adjustment valve 4 touches the block-shaped stoppers 65, formed in the aforementioned limit cap 6; therefore, the rotation of the aforementioned adjustment valve 4 is limited to a 90° range of rotation.
According to this embodiment, there is the advantage that, unlike the adjustment valve in the working embodiment that was shown in
Furthermore, in this working embodiment, a pair of arc-shaped cut-out parts 66, 66 are placed opposite each other so that the axial part 41 of the second engaging groove 44 of the aforementioned adjustment valve 4 is inserted in the center of the straight-line part of the aforementioned oval insertion hole 61, and a smooth rotation is made possible, without obstruction, when the adjustment valve 4 is rotated coaxially with the insertion hole 61 in the second step position.
As mentioned above, by means of this embodiment, in a carburetor suitable for feeding fuel to a general-purpose engine which has an adjustment valve for the quantity of fuel flow and a means for controlling this adjustment valve, the generation of additional parts is avoided, the assembly procedure is not greatly changed from the prior art, and removal of the aforementioned cap which is placed in the aforementioned sleeve by the user's intentional vandalism can be made very difficult in the working embodiments.
In the foregoing specification, all features, elements, components, functions, and steps described with respect to any embodiment provided herein are intended to be freely combinable and substitutable with those from any other embodiment. If a certain feature, element, component, function, or step is described with respect to only one embodiment, then it should be understood that that feature, element, component, function, or step can be used with every other embodiment described herein unless explicitly stated otherwise. This paragraph therefore serves as antecedent basis and written support for the introduction of claims, at any time, that combine features, elements, components, functions, and steps from different embodiments, or that substitute features, elements, components, functions, and steps from one embodiment with those of another, even if the following description does not explicitly state, in a particular instance, that such combinations or substitutions are possible. Express recitation of every possible combination and substitution is overly burdensome, especially given that the permissibility of each and every such combination and substitution will be readily recognized by those of ordinary skill in the art upon reading this description.
In many instances entities are described herein as being coupled to other entities. It should be understood that the terms “coupled” and “connected” (or any of their forms) are used interchangeably herein and, in both cases, are generic to the direct coupling of two entities (without any non-negligible intervening entities) and the indirect coupling of two entities (with one or more non-negligible intervening entities). Where entities are shown as being directly coupled together, or described as coupled together without description of any intervening entity, it should be understood that those entities can be indirectly coupled together as well unless the context clearly dictates otherwise.
While the above is a complete description of exemplary specific embodiments, additional embodiments are also possible. Thus, the above description should not be taken as limiting the scope of the invention, which is defined by the appended claims along with their full scope of equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-39518 | Mar 2017 | JP | national |
