CN112343721A

CN112343721A - Throttle device of engine

Info

Publication number: CN112343721A
Application number: CN202010789445.8A
Authority: CN
Inventors: 土屋尚哉
Original assignee: Mikuni Corp
Current assignee: Mikuni Corp
Priority date: 2019-08-07
Filing date: 2020-08-07
Publication date: 2021-02-09
Anticipated expiration: 2040-08-07
Also published as: JP7330804B2; CN112343721B; JP2021025491A

Abstract

A throttle device for an engine, which can prevent loosening of an idle speed adjusting screw when an accelerator is returned while ensuring a good adjusting function of an idle speed air inflow. The throttling device comprises: a throttle shaft supporting a throttle valve of the valve main body; a throttle lever that transmits the force of the return spring on the closing side and the accelerator operation of the driver to a throttle shaft; and an idle speed adjustment mechanism that is cantilever-supported from the valve main body via the arm portion of the bracket. The idle speed adjustment mechanism includes: an idle speed adjusting screw for pressing and reducing the compression spring and screwing the compression spring to the female thread of the arm part; and a stopper of the throttle lever, which abuts against the idle adjustment screw through a return spring and holds the throttle valve at a predetermined opening. The throttle device further includes a fitting attached to the arm portion of the bracket, having a through hole formed therethrough corresponding to the female screw, and having a seat surface of the compression spring inclined with respect to a surface perpendicular to the idle adjustment screw.

Description

Throttle device of engine

Technical Field

The present invention relates to a throttle device of an engine, and more particularly to a throttle device including an idle adjustment screw that adjusts an intake air amount during idle operation.

Background

In the above-described throttle device, the throttle valve is disposed in a throttle hole formed in the valve main body and is supported by a throttle shaft, and the throttle valve is biased to the closing side by a return spring. The throttle of the vehicle is connected to a throttle lever provided at one end of a throttle shaft via a throttle wire, and the throttle valve is opened and closed together with the throttle shaft in accordance with the throttle operation by the driver.

In order to adjust the engine rotational speed during idling, the throttle device is provided with an idling adjustment mechanism that adjusts the idling intake air amount. An idle adjustment screw is screwed into one side surface of the valve body, and is biased in a direction away from the valve body by a compression spring. When the throttle lever is rotated toward the closing side, a stopper provided on one side of the throttle lever abuts against the tip of the idle adjustment screw and is restricted from rotating, and the minimum opening degree of the throttle valve is determined in accordance with the rotation angle at that time. Therefore, the idle rotation speed can be adjusted by adjusting the amount of intake air to the engine by changing the screwing position of the idle adjustment screw.

Since various components attached to the engine are disposed around the throttle device mounted on the vehicle, the idle speed adjustment mechanism may interfere with the peripheral components when directly mounted on the valve main body. As a countermeasure, there is a throttle device in which an idle speed adjustment mechanism is disposed separately from a valve main body via a bracket. From the viewpoint of manufacturing cost, the bracket is made of a sheet metal formed by bending a steel plate, for example, a base portion of the bracket is fixed to one side surface of the valve main body, and an idle speed adjustment screw and a compression spring are provided on an arm portion bent at a right angle from the base portion. The idle speed adjustment mechanism is cantilever-supported separately from the valve main body via the arm portion of the bracket, thereby preventing interference with peripheral components.

However, in the throttle device using the bracket as described above, there is a case where a problem occurs at the time of returning the accelerator. For example, when the accelerator is quickly returned to rapidly decelerate the vehicle during full-force acceleration, the throttle valve is rapidly closed from full opening by the biasing force of the return spring, and the throttle lever is violently collided with the idle adjustment screw. Since the idle adjustment screw is loosened by the impact at this time, a desired idle intake air amount cannot be achieved, and there is a problem that a trouble such as idling deviation occurs.

As a countermeasure against such a problem, for example, in the technique disclosed in japanese patent laid-open No. 57-129232, a roll mark is formed on an outer peripheral surface of an idle speed adjustment screw, a rubber holder is provided on a bracket supporting the idle speed adjustment screw, and the idle speed adjustment screw is prevented from loosening by contact with each other.

However, the countermeasure described in japanese patent application laid-open No. 57-129232 has a problem of adversely affecting the function of adjusting the idle intake air amount originally requested by the throttle device.

In other words, although the above-described countermeasure provides the looseness prevention by the strong friction generated between the roll marks and the rubber holder, the friction hinders smooth rotation of the idle adjustment screw when adjusting the idle intake air amount, and makes it difficult to perform the adjustment work. Further, since the elasticity of the rubber holder always acts on the idle adjustment screw in a direction of inhibiting the rotation, the idle adjustment screw adjusted to the optimum screwing position is slightly returned, and there is a problem that precise adjustment is difficult.

Disclosure of Invention

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an engine throttle device capable of preventing loosening of an idle speed adjustment screw during an accelerator return operation while ensuring a good idle speed intake air amount adjustment function.

In order to achieve the above object, a throttle device for an engine according to the present invention includes: a throttle valve provided in the valve main body; a throttle shaft that supports a throttle valve; a throttle lever that transmits the urging force of the return spring on the closing side to the throttle shaft and transmits the accelerator operation of the driver to the throttle shaft; and an idle speed adjustment mechanism that is fixed to the valve main body and is supported by an arm portion of the bracket in a cantilever manner, the idle speed adjustment mechanism including: an idle adjustment screw inserted through the compression spring and screwed to the female screw of the arm portion in a state where the compression spring is compressed and reduced; and a stopper portion of the throttle lever that abuts against a tip end of the idle adjustment screw by an urging force of the return spring and holds the throttle valve at a predetermined opening degree, wherein the throttle device of the engine includes a fitting that is attached to an arm portion of the bracket, has a through hole that is provided so as to correspond to a female screw of the arm portion, and has a seat surface that abuts against one end of the compression spring, the seat surface being formed to be inclined with respect to a surface orthogonal to an axis of the idle adjustment screw.

As another aspect, the attachment may be provided with a holding portion that fits into the arm portion of the bracket, and an abutment regulating portion that regulates the fitting of the holding portion by abutment with the bracket.

Alternatively, the holding portion may be a holding groove formed between a pair of leg portions having a key-like tip, and when the holding groove is fitted into the arm portion of the bracket, the pair of leg portions may hold the arm portion while elastically sandwiching the arm portion and hook the tip of each leg portion to the arm portion.

Alternatively, when the abutment regulating portion of the fitting abuts against the bracket, the through hole of the fitting may be aligned with the female screw of the arm portion.

According to the throttle device for an engine of the present invention, while a good function of adjusting the idle intake air amount can be ensured, the idle adjustment screw can be prevented from loosening in advance when the accelerator is returned.

Drawings

Fig. 1 is a perspective view showing a throttle device of an engine according to an embodiment.

Fig. 2 is a sectional view taken along line II-II of fig. 1.

Fig. 3 is a view from direction a of fig. 1.

Fig. 4 is an exploded perspective view of the throttle lever and the idle speed adjustment mechanism separated from the throttle device.

Fig. 5 is an exploded perspective view showing the idle speed adjustment mechanism.

Fig. 6 is a sectional view taken along line VI-VI of fig. 5, showing the inclination of the seat surface and the offset state of the compression spring.

Fig. 7 is also a sectional view taken along line VII-VII of fig. 5.

Fig. 8 is a cross-sectional view corresponding to fig. 6, showing another example in which the inclination direction of the seat face is different by 90 ° from that of the embodiment.

Fig. 9 is a cross-sectional view corresponding to fig. 7, showing another example.

Fig. 10 is a cross-sectional view corresponding to fig. 7, showing another example in which a gasket is used as a seat surface.

(symbol description)

1 throttling device

2. 3 valve body

6 throttling valve

8 throttle valve shaft

14 return spring

15 throttle lever

15b stopper

20 idle speed regulating mechanism

21 bracket

21b arm part

21c female thread

23 fittings

24a seat surface

24b through hole

25 feet

25a front end

26 abut against the restricting part

27 holding groove (holding part)

29 idle speed adjusting screw

30 compression spring

Detailed Description

Hereinafter, an embodiment of the present invention will be described as a throttle device for a four-cylinder engine for a motorcycle.

As shown in fig. 1 and 2, the throttle device 1 of the present embodiment is formed by joining a first valve body 2 and a second valve body 3 each including a pair of

orifices

2a and 3 a. Although not shown, in the state of being mounted on the motorcycle, hoses from the air cleaner are connected to one ends of the

respective orifices

2a and 3a corresponding to the right side in fig. 1, and the intake manifold of the engine is connected to the other end on the opposite side. During engine operation, intake air filtered by the air cleaner flows through the

respective throttle holes

2a, 3a and is guided to the intake manifold, and the intake air amount is adjusted by the throttle valve 6 in the

respective throttle holes

2a, 3a described below.

A fuel injection valve 4 is attached to the lower side of the first valve body 2 and the second valve body 3 in a posture in which the tip end faces the

orifices

2a and 3a, and pressurized fuel is supplied from an unillustrated fuel pump via a delivery pipe 5. Each fuel injection valve 4 is opened and closed in synchronization with the fuel cycle of each cylinder of the engine, and fuel is injected into the intake manifold of the corresponding cylinder in response to the opening and closing.

Since the throttle device 1 of the present embodiment includes the starting throttle valve 7 in addition to the throttle valve 6 for adjusting the output of the engine, as shown in fig. 2, two

throttle shafts

8, 9 that respectively penetrate the upstream side and the downstream side in the intake air flow direction of the

respective orifices

2a, 3a are rotatably supported by the first valve main body 2 and the second valve main body 3. In each of the

orifices

2a and 3a, the output adjustment throttle 6 is fixed to the downstream throttle shaft 8 by a screw 10, and the start throttle 7 is fixed to the upstream throttle shaft 9 by a screw 11.

One end of each

throttle shaft

8, 9 protrudes from one side surface of the first valve body 2 corresponding to the left side of fig. 1, and a start-time drive mechanism 12 is connected to an end of the throttle shaft 9 on the upstream side. Each throttle valve 7 for starting is kept in a fully open state during engine operation, and is driven to the closed side by the start-time driving mechanism 12 at the time of engine start, and is limited to an intake air amount suitable for start.

As shown in fig. 3 and 4, a return spring 14 is wound around an end portion of the throttle shaft 8 on the downstream side, a disc-shaped body portion 15a of the throttle lever 15 is fastened to the nut 17 via a washer 16, and a plate-shaped stopper portion 15b is integrally formed on one side of the outer periphery of the body portion 15 a. The return spring 14 has one end hooked to the first valve main body 2 and the other end hooked to one side of the throttle lever 15, and biases the throttle lever 15 in a direction corresponding to the closing side of the throttle valve 6 for output adjustment.

Although not shown, a vehicle accelerator is connected to a connection hole 15c provided in the body portion 15a of the throttle lever 15 via an accelerator cable. Therefore, the accelerator operation of the driver is mechanically transmitted to the throttle lever 15 via the throttle wire, and each of the throttle valves 6 for output adjustment is opened and closed via the throttle shaft 8 in accordance with the rotation of the throttle lever 15 in both forward and reverse directions. Specifically, the throttle lever 15 is rotated about the axis Lth of the throttle shaft 8 between two positions, an idle position indicated by a solid line and a fully open position indicated by a phantom line in fig. 3 in which rotation is restricted by the idle adjustment mechanism 20 described below. At the idle position, each throttle valve 6 is held at the minimum opening degree, and at the fully open position, each throttle valve 6 is held at the maximum opening degree.

An idle adjustment mechanism 20 that adjusts the idle intake air amount is provided at a position close to the throttle lever 15 as described above. As shown in fig. 4 and 5, a bracket 21 made of a so-called sheet metal formed by bending a steel plate is disposed on one side surface of the first valve main body 2, and a base portion 21a of the bracket 21 is fixed to the first valve main body 2 by a pair of screws 22. The arm portion 21b is bent at a right angle from the base portion 21a to the opposite side of the first valve main body 2, and extends in the throttle axis direction. The arm portion 21b faces the stopper portion 15b of the throttle lever 15, and a female screw 21c is formed at the tip of the arm portion 21 b.

The attachment 23 is attached to the arm portion 21b of the bracket 21 from the opposite side of the first valve body 2. Since the fitting 23 relates to a characteristic portion of the present invention, a side surface opposite to the throttle lever 15 is a seat surface 24a, and a through hole 24b corresponding to the female screw 21c of the arm portion 21b is provided to penetrate the seat surface 24a, which will be described in detail later.

An idle adjustment screw 29 is screwed into the female screw 21c of the arm portion 21b of the bracket 21 from the opposite side to the throttle lever 15 through a through hole 24b of the attachment 23. The idle adjustment screw 29 is composed of a male screw 29a and a head 29b, and the male screw 29a is screwed to the female screw 21c of the arm 21b in a state of being inserted through the compression spring 30 and the resin washer 31, and the tip thereof protrudes from the arm 21b toward the throttle lever 15. The compression spring 30 is compressed and contracted between the seat surface 24a of the metal fitting 23 and the head 29b of the idle adjustment screw 29, and its urging force acts in a direction to separate the idle adjustment screw 29 from the seat surface 24a of the metal fitting 23.

As shown by arrow a in fig. 3, when the throttle lever 15 is rotated toward the closing side about the axis Lth of the throttle shaft 8, the stopper 15b abuts against the tip of the male screw 29a from a direction substantially along the axis Lscw of the idle adjustment screw 29 as indicated by arrow b. Thereby, the rotation of the throttle lever 15 is restricted at the idle position, and the minimum opening degree of each throttle valve 6 is determined in accordance with the rotation angle at that time. Therefore, the amount of intake air to the engine and hence the idle rotation speed can be adjusted by changing the screwing position of the idle adjustment screw 29.

As described above, the bracket 21 is fixed to one side surface of the first valve main body 2, and the idle speed adjustment mechanism 20 is supported by the first valve main body 2 via the arm portion 21 b. As a result, the idle speed adjustment mechanism 20 is disposed separately from the first valve main body 2, and interference with various components attached to the engine disposed around the throttle device 1 is prevented.

In a general idle adjustment mechanism, the compression spring 30 is interposed between the arm portion 21b of the bracket 21 and the head portion 29b of the idle adjustment screw 20. The urging force of the compression spring 30 acts in a direction to separate the idle adjustment screw 29 from the arm portion 21b of the bracket 21, and the current screwing position of the idle adjustment screw 29 is held by the urging force. Specifically, friction is generated between the female thread 21c of the arm portion 21b and the male thread 29a of the idle adjustment screw 20 by the biasing force of the compression spring 30, friction is generated between one end of the compression spring 30 and the arm portion 21b, and between the other end of the compression spring 30 and the head 29b of the idle adjustment screw 29, respectively, and the rotation of the idle adjustment screw 29 is regulated by the friction, and the idle adjustment screw 29 is held at the current screwing position.

When the stopper portion 15b of the throttle lever 15 collides with the tip end of the male thread 29a of the idle adjustment screw 29 as described above due to the return operation of the accelerator, the impact thereof is input to the arm portion 21b of the bracket 21 via the idle adjustment screw 29. For example, the bracket 21 made of a sheet metal is inherently low in rigidity as compared with a bracket made of die-cast aluminum, and the arm portion 21b, which has one side surface facing the stopper portion 15b and functions as a cantilever beam, is also likely to be deflected in the cross-sectional shape by an impact input from the stopper portion 15 b.

Therefore, the arm portion 21b is bent in the tilting direction starting from the base portion 21a, for example. The compression spring 30 is instantaneously contracted by the abrupt positional displacement of the arm portion 21b at this time, and the biasing force to the idle speed adjustment screw 29, in other words, the original installation load is eliminated or reduced. As a result, friction between the bracket 21 side and the idle adjustment screw 29 side due to the biasing force is reduced, and the idle adjustment screw 29 rotates in the loosening direction.

As a countermeasure for preventing the loosening phenomenon of the idle speed adjustment screw 29 as described above, the present inventors have focused on the compression spring 30.

As described above, the compression spring 30 acts in a direction to separate the idle adjustment screw 29 from the arm portion 21b, and for example, as shown in fig. 6, the axis Lsp of the compression spring 30 substantially coincides with the axis Lscw of the idle adjustment screw 29, and all portions of the inner periphery of the compression spring 30 are spaced apart from the outer peripheral surface of the male thread 29a of the idle adjustment screw 29. When the axis Lsp of the compression spring 30 arranged as described above is intentionally offset from the axis Lscw of the idle adjustment screw 29, for example, as shown in fig. 7, one side of the inner periphery of the compression spring 30 is pressed against the outer peripheral surface of the male thread 29a of the idle adjustment screw 29. The friction generated therebetween at this time acts in a direction that suppresses the compression spring 30 from contracting due to the impact input and suppresses the idle speed adjustment screw 29 from rotating.

Specifically, the compression spring 30 is instantaneously reduced when the impact input is inhibited by friction with the idle adjustment screw 29, and continues to apply force to the idle adjustment screw 29. Further, friction generated by the press-contact of the compression spring 30 acts in a direction of blocking the rotation of the idle speed adjustment screw 29. Hereinafter, the state in which the axis Lsp of the compression spring 30 is offset from the axis Lscw of the idle adjustment screw 29 as described above may be simply referred to as the offset of the compression spring 30.

The biasing of the compression spring 30 may be achieved by forming a seat surface on the arm portion 21b, against which one end of the compression spring 30 abuts, to have an angle with respect to a plane F orthogonal to the axis Lscw of the idle adjustment screw 29. As a result, the seating surface is inclined with respect to the plane F orthogonal to the axis Lscw of the idle adjustment screw 29. When the seating surface is inclined, the distance between the seating surface and the head 29b of the idle adjustment screw 29 is not uniform over the entire circumference around the axis Lsp of the compression spring 30, and the compression spring 30 is displaced toward the shorter side. As a result, the portion of the inner periphery of the compression spring 30 on the opposite side to the offset direction is pressed against the outer peripheral surface of the male thread 29a of the idle adjustment screw 29, and friction occurs therebetween as described above.

In order to incline the seat surface, it is conceivable to form the arm portion 21b of the bracket 21 made of sheet metal into a twisted shape.

The inclination angle α of the seat face of about 10 ° is required to offset the compression spring 30, but such an inclination angle α is difficult to form by twisting the short arm portion 21 b. When the inclination angle α of the seating surface is 0, only the female screw 21c into which the idle adjustment screw 29 is screwed may be formed at a right angle to the arm portion 21 b. In contrast, when the seat surface is inclined, the female screw 21c needs to be formed in the arm portion 21b so as to be inclined at an angle corresponding to the inclination angle α, and the machining of the female screw 21c becomes significantly complicated. In this case, it is practically difficult to impart the inclination angle α to the seat surface by twisting the arm portion 21 b.

Therefore, in the present invention, the attachment 23 is attached to the arm portion 21b of the bracket 21, and the inclination angle α is applied to the seat surface 24a on the attachment 23, and the attachment 23 will be described in detail below.

First, the inclination direction and the inclination angle α of the seat surface 24a of the metal fitting 23 will be described. The idling adjustment screw 29 is prevented from loosening by pressing the compression spring 30 against the outer peripheral surface of the idling adjustment screw 29, but the effect thereof differs depending on the inclination direction of the seating surface 24 a. In the idle adjustment mechanism 20 of the present embodiment, when the stopper portion 15b of the throttle lever 15 collides with the idle adjustment screw 29 from the arrow b direction in fig. 7 due to the quick accelerator return operation, the arm portion 21b is bent in the tilting direction indicated by the arrow c starting from the base portion 21a of the bracket 21, and the idle adjustment screw 29 is abruptly positionally displaced in the same direction.

At this time, if the compression spring 30 is displaced downward in fig. 7, the pressure contact with the idle adjustment screw 29 is further enhanced by the deflection of the arm portion 21b, and the looseness prevention effect is improved. Therefore, the inclination direction of the seat surface 24a in the present embodiment is set such that the distance between the seat surface 24a and the head portion 29b of the idle adjustment screw 29 is short on the opposite side of the base portion 21a, and as a result, the compression spring 30 is displaced downward in fig. 7.

Of course, the present invention is not limited to the above-described inclination direction of the seat surface 24 a. This is because, when the specifications of the throttle device 1, for example, the shape of the bracket 21, the collision angle between the throttle lever 15 and the idle adjustment screw 29, and the like are different, the bent state of the arm portion 21b at the time of impact input changes, and accordingly, the desired inclination direction of the seating surface 24a also changes.

Further, with respect to the inclination angle α of the seating surface 24a, the greater the inclination angle α is, the stronger the compression spring 30 is pressed against the idle adjustment screw 29, thereby improving the loosening prevention effect. On the other hand, the greater the impact input from the throttle lever 15, the more likely the idle speed adjustment screw 29 is loosened, and the magnitude of the impact at this time differs depending on various conditions such as the biasing force of the return spring 14. For example, in the four-hole throttle device 1 according to the present embodiment, a larger biasing force is applied to the return spring 14 than in the case of a single-hole throttle device. Therefore, the deflection of the arm portion 21b increases together with the impact force input to the idle adjustment screw 29, and the inclination angle α of the seat surface 24a needs to be relatively increased in order to prevent the backlash.

Therefore, in the present embodiment, the inclination angle α of the seat face 24a is set to be 10 ° relatively large, but the present invention is not limited to this, and the inclination angle α of the seat face 24a may be set to such an extent that looseness can be prevented in consideration of the specification of the throttle device 1 and the like.

As shown in fig. 5 to 7, the metal fitting 23 is composed of a main body portion 24 on which a seat surface 24a of the compression spring 30 is formed, a pair of leg portions 25 for fixing the metal fitting 23 to the arm portion 21b of the bracket 21, and an abutment restricting portion 26 for positioning the metal fitting 23, and is integrally injection-molded by a synthetic resin material such as PP (polypropylene). The material of the metal fitting 23 is not limited to this, and may be made of die-cast aluminum, for example.

A flat seat surface 24a is formed on one side surface of the body portion 24, and a pair of legs 25 extend from the other side surface of the body portion 24. The front ends 25a of the legs 25 are formed in a key shape, and a holding groove 27 is formed between the legs 25. The metal fitting 23 is disposed in a posture in which the other side surface of the main body portion 24 is overlapped with the arm portion 21b of the bracket 21, and the holding groove 27 between the both leg portions 25 is fitted into the arm portion 21b of the bracket 21. The arm portions 21b are elastically sandwiched by the leg portions 25 located on both sides, and are hooked on the leading ends 25a of the leg portions 25, thereby preventing the attachment 23 from coming off the arm portions 21 b. In the present embodiment, the holding groove 27 functions as an inventive holding portion.

The holding portion of the present invention is not limited to the groove shape as the holding groove 27, and may be formed into a hole shape as a holding portion by connecting the distal ends 25a of the both leg portions 25 and fitting into the holding hole of the arm portion 21 b. However, when the holding groove 27 is formed by the pair of leg portions 25, the following effects can be obtained: it is possible to impart good elasticity to each leg portion 25 and to save the amount of resin required for injection molding of the fitting 23 compared to when both leg portions 25 are connected.

The abutment restricting portion 26 extends from the main body portion 24 toward the base portion 21a of the bracket 21, and the abutment restricting portion 26 has a rectangular cross section and its tip abuts against the base portion 21 a. Further, a through hole 24b is provided in the body portion 24 so as to penetrate therethrough in correspondence with the female screw 21c of the arm portion 21b and open to the seat surface 24a, and a male screw 29a of an idle adjustment screw 29 is screwed to the female screw 21c via the through hole 24b, and one end of a compression spring 30 is in contact with the seat surface 24 a. As described above, the inclination direction of the seat surface 24a is set such that the distance between the seat surface 24a and the head 29b of the idle adjustment screw 29 is shorter on the opposite side of the base portion 21a, and the inclination angle α is set to 10 °. As a result, the compression spring 30 is displaced downward in fig. 7.

In the throttle device 1 configured as described above, as shown in fig. 7, when the stopper portion 15b of the throttle lever 15 collides with the tip end of the idle adjustment screw 29 due to the quick accelerator return operation, the arm portion 21b is deflected starting from the base portion 21a of the bracket 21. At this time, the rapid position displacement of the arm portion 21b acts in a direction to instantaneously reduce the compression spring 30, but the reduction of the compression spring 30 can be inhibited by friction generated between the compression spring 30 and the idle speed adjustment screw 29. Therefore, the idle speed adjustment screw 29 continues to receive the force in the direction of the axis Lscw by the compression spring 30, thereby preventing rotation. In addition, the friction generated by the pressure contact of the compression spring 30 acts in a direction that hinders the rotation of the idle adjustment screw 29, which also contributes to the prevention of rotation.

In addition, in the present embodiment, the inclination direction of the seating surface 24a is set so that the pressure contact with the idle adjustment screw 29 is further increased by the deflection of the arm portion 21b accompanying the input of the impact. Therefore, it is possible to strongly press the compression spring 30 against the idle adjustment screw 29 and further increase the friction therebetween, which also greatly contributes to preventing the idle adjustment screw 29 from rotating. For the above reasons, according to the throttle device 1 of the present embodiment, the idle adjustment screw 29 can be prevented from loosening even if the quick accelerator return operation is performed, and a problem such as idling deviation when the desired idle intake air amount cannot be achieved due to the loosening can be prevented. In addition, the throttle device 1 of the present embodiment can secure a good function of adjusting the idle intake air amount while achieving the above-described looseness prevention effect.

In addition, the fitting 23 is attached to the arm portion 21b for the purpose of biasing the compression spring 30 not only because the twisting work of the arm portion 21b itself is difficult, but also because other advantages can be obtained.

That is, in the throttle device 1, a plurality of derivative models having different specifications may be manufactured, and various conditions such as the positional relationship between the idle speed adjustment screw 29 and the throttle lever 15 and the number of orifices may be different between the derivative models. In the former case, the collision angle between the throttle lever 15 and the idle adjustment screw 29 is different, and in the latter case, the magnitude of the impact input to the idle adjustment screw 29 is different due to the difference in the urging force of the return spring 14. In any case, since the deflection state of the arm portion 21b at the time of impact input differs, the desired inclination direction and inclination angle α of the seat surface 24a also differ.

Therefore, when the bracket 21 is separately manufactured in accordance with the seat surface 24a required for each derivative model, the manufacturing cost increases. In the present embodiment, only the metal fittings 23 corresponding to the seating surfaces 24a required in the respective derivative models can be manufactured, and the metal fittings can be shared by the respective derivative models with respect to the bracket 21. Therefore, the manufacturing cost of the throttle device 1 can be reduced in combination with the bracket 21 itself being made of an inexpensive sheet metal.

On the other hand, the pair of leg portions 25 and the contact restricting portion 26 of the attachment 23 play a unique role in the assembly operation of the idle speed adjustment mechanism 20, and the respective roles will be described below together with the assembly procedure.

First, the bracket 21 is fixed to one side surface of the first valve body 2 by the screws 22, and the holding groove 27 of the attachment 23 is gradually fitted into the arm portion 21 b. The arm portion 21b is elastically sandwiched by the leg portions 25 on both sides, and is hooked on the key-shaped distal ends 25a of the leg portions 25. When the fitting operation is further continued, the abutment regulating portion 26 of the fitting 23 abuts on the base portion 21a of the bracket 21 at a certain point of time, the further fitting operation is regulated, and the through hole 24b of the fitting 23 is made to coincide with the female screw 21c of the arm portion 21 b.

Next, the compression spring 30 and the resin washer 31 are inserted through the male screw 29a of the idle adjustment screw 29, and the male screw 29a is screwed to the female screw 21c of the arm portion 21b through the through hole 24b of the fitting 23. The compression spring 30 is compressed and contracted between the seat surface 24a of the attachment 23 and the head 29b of the idle adjustment screw 29, and the tip of the male screw 29a protrudes from the arm portion 21b toward the throttle lever 15. The compression spring 30 is displaced to the opposite side of the base portion 21a by the influence of the inclination of the seating surface 24a, and the portion of the inner periphery on the base portion 21a side is pressed against the outer peripheral surface of the male screw 29a of the idle adjustment screw 29, thereby completing the assembly of the idle adjustment mechanism 20.

As described above, when the holding groove 27 of the attachment 23 is fitted into the arm portion 21b, the fitting operation is continued until the fitting operation is restricted by the abutment of the abutment restricting portion 26, whereby the through hole 24b can be automatically aligned with the female screw 21c and the idle adjustment screw 29 can be screwed. Therefore, it is not necessary to perform the fitting operation while visually checking the positional relationship between the through hole 24b and the female screw 21c, and the metal fitting 23 can be easily attached to the bracket 21.

After the attachment of the attachment 23, as the next operation, the compression spring 30 and the resin washer 31 are inserted into the idle speed adjustment screw 29, and the idle speed adjustment screw 29 is screwed. In this case, if the attachment 23 may come off the arm portion 21b, the attachment 23 needs to be gripped and the next operation is performed to prevent the detachment, which makes the operation very difficult to perform.

In the present embodiment, the attached metal fitting 23 is elastically sandwiched between the arm portions 21b by the pair of leg portions 25, and therefore, the metal fitting can be prevented from coming off the arm portions 21b in a direction opposite to the fitting direction by friction between the metal fitting and the arm portions. Meanwhile, since the front ends 25a of the foot portions 25 of the mounted fittings 23 are hooked on both sides of the arm portions 21b, the fittings 23 are prevented from being separated from the arm portions 21 b. As a result, when the attachment is made to the arm portion 21b, the attachment state of the attachment 23 is maintained, and the attachment is prevented from coming off the arm portion 21 b. The operator can therefore remove the hand from the attached attachment 23 and perform the next work using both hands. For the above reasons, a completely different effect that the idle speed adjustment mechanism 20 can be easily assembled can also be obtained.

The above-described inclination direction of the seating surface 24a of the attachment 23 is an example, and as described above, when the specification of the throttle device 1 is different, the bent state of the arm portion 21b at the time of impact input changes, and the desired inclination direction of the seating surface 24a also changes. Therefore, another example in which the inclination direction of the seat surface 24a is different by 90 ° from that of the present embodiment will be described with reference to fig. 8 and 9.

In this other example, it is assumed that the idle adjustment screw 29 is displaced to the lower position in fig. 8 by the deflection of the arm portion 21b due to the impact input. Therefore, the inclination direction of the seat surface 24a of the attachment 23 is set so that the distance between the seat surface 24a and the head 29b of the idle adjustment screw 29 becomes shorter at the upper side in fig. 8, thereby deviating the compression spring 30 upward in fig. 8. Therefore, when the position of the idle adjustment screw 29 is displaced in accordance with the deflection of the arm portion 21b due to the impact input, the pressure contact of the compression spring 30 is further increased, and the loosening of the idle adjustment screw 20 can be further reliably prevented.

The embodiments have been described above, but the embodiments of the present invention are not limited to the above embodiments. For example, although the embodiment described above is embodied as the throttle device 1 of an engine for a motorcycle, the present invention is not limited thereto. For example, the throttle device may be embodied as an engine mounted on an ATV (all terrain Vehicle) or an engine for a generator as a power source. In the above embodiment, the idle speed adjustment mechanism 20 is provided on one side surface of the first valve body 2, but the idle speed adjustment mechanism 20 may be provided between the first valve body 2 and the second valve body 3, for example.

Although the flat seat surface 24a is formed in the body portion 24 of the metal fitting 23 in the present embodiment, for example, as shown in fig. 10, a stepped portion 41 may be formed in the body portion 24, and a washer 42 may be interposed between the stepped portion 41 and one end of the compression spring 30. In this case, the present invention also includes a mode in which the washer 42 is disposed obliquely with respect to the plane F orthogonal to the axis Lscw of the idle adjustment screw 29, and one side surface of the washer 42 functions as the seat surface 24a of the compression spring 30.

Claims

1. A throttle device for an engine, comprising: a throttle valve provided in the valve main body; a throttle shaft that supports the throttle valve; a throttle lever that transmits an urging force of a return spring on a closing side to the throttle shaft and transmits an accelerator operation of a driver to the throttle shaft; and an idle speed adjustment mechanism fixed to the valve main body and supported by an arm portion of a bracket in a cantilever manner,

the idle speed adjustment mechanism includes: an idle adjustment screw inserted through a compression spring and screwed to the female screw of the arm portion in a state where the compression spring is compressed and reduced; and a stopper of the throttle lever, the stopper abutting against a tip end of the idle adjustment screw by an urging force of the return spring and holding the throttle valve at a predetermined opening degree,

the throttle device of the engine includes a fitting that is attached to an arm portion of the bracket, has a through hole that is provided so as to pass through the arm portion in correspondence with a female screw of the arm portion, and has a seat surface that is in contact with one end of the compression spring and that is formed obliquely with respect to a surface orthogonal to an axis of the idle adjustment screw.

2. The throttle device of engine according to claim 1,

the attachment is provided with a holding portion that fits into the arm portion of the bracket, and an abutment regulating portion that regulates the fitting of the holding portion by abutment with the bracket.

3. The throttle device of an engine according to claim 2,

the holding part is a holding groove formed between a pair of leg parts with key-shaped front ends,

when the holding groove is fitted into the arm portion of the bracket, the pair of leg portions elastically sandwich the arm portion and hook the respective leading ends to the arm portion.

4. The throttle device of an engine according to claim 2 or 3,

when the abutment regulating portion of the fitting abuts against the bracket, the through hole of the fitting coincides with the female thread of the arm portion.