JPH0270922A - Actuator for controlling supercharge pressure - Google Patents

Abstract

PURPOSE:To improve the durability of an actuator which can be operated by the negative and positive pressure by fixing the inner edge in the axis line direction of a bellows in the recessed part of a casing and constituting the outer edge from a movable part joined with a driving rod. CONSTITUTION:As for an actuator 20, a positive pressure is introduced into a positive pressure chamber 46 from a positive pressure introducing nipple 48, and then a driving rod 29 is driven downwardly through a diaphragm 26 or against the springy force of a compression coil spring 31. Further, when a negative pressure is introduced into a negative pressure chamber 45 from a negative pressure introducing nipple 47, the driving rod 29 is driven downward through the diaphragm 26. Since, at this time, the driving rod 29 is guided by a bearing member 33, the smooth operation of the actuator 20 can be secured.

Description

Detailed Description of the Invention [Objective of the Invention] <Industrial Application Field> The present invention has an introduction path for introducing positive pressure and negative pressure, and can be operated by both positive pressure and negative pressure. The present invention relates to an actuator of the above type, and particularly to an actuator of the above type suitable for controlling a supercharger.

<Conventional technology> Conventionally, a type of supercharger called a turbocharger has been used for the purpose of increasing engine output.
In order to always perform suitable supercharging especially for engines whose operating loads and operating speed ranges vary greatly, such as vehicle engines, for example, Japanese Patent Laid-Open No. 62-282 published by the same applicant has been proposed.
A variable passenger compartment turbocharger as disclosed in Japanese Patent No. 122 has been proposed. In such a supercharger, for example, the speed at which the exhaust gas flows into the turbine is controlled by appropriately tilting the vanes provided in the exhaust gas inflow path, so that the speed at which the engine rotates is low. The supercharging effect can be ensured even in this case.

In order to control such a variable capacity supercharger, some kind of actuator is required, and the driving source for this could be to use the pressure in the engine's intake pipe, but if the engine performs supercharging, In some cases, the pressure inside the intake pipe may vary from positive pressure to negative pressure. In such a case, an actuator using two diaphragms that can be operated by either positive pressure or negative pressure can be used, as disclosed in Japanese Patent Laid-Open No. 63-5117, for example. However, in such an actuator, for example, when driven by positive pressure, the pressure within the negative pressure chamber may be approximately equal to atmospheric pressure, and in such a case, the negative pressure is applied according to the displacement of the actuating end of the actuator. However, since no tension is applied to the negative pressure diaphragm at this time, the negative pressure diaphragm may wrinkle or twist as the actuator operates, causing damage to the negative pressure diaphragm. In some cases, undesirable stress may be applied.

<Problems to be Solved by the Invention> In view of the problems of the prior art, the main object of the present invention is to provide an actuator that can be operated by either positive pressure or negative pressure and is suitable for controlling boost pressure. The purpose is to improve the durability of

[Structure of the Invention (Means for Solving the Problem)] According to the present invention, an actuator for controlling boost pressure that can be operated by either positive pressure or negative pressure, which has a casing and , a diaphragm separating the casing into a negative pressure chamber and a positive pressure chamber, a bellows separating the negative pressure chamber from the atmosphere, and a drive rod coupled to both movable parts of the diaphragm and the bellows, For supercharging pressure control, wherein the axially inner end of the bellows is a fixed end fixed in the recess of the casing, and the axially outer end thereof is the movable part coupled to the drive rod. This is achieved by providing an actuator.

<Function> In this way, tension is always applied to the diaphragm when either positive pressure or negative pressure is applied, while the bellows does not wrinkle or twist even when it is not under tension. As described above, the problems of the prior art are overcome. In particular, by receiving the bellows in the cylindrical recessed part of the casing, it is possible to protect the bellows and downsize the actuator, and by guiding the drive rod through the inner cylindrical part, the actuator can be made durable. performance and smooth operation.

Embodiments The present invention will now be described in detail with reference to specific embodiments with reference to the accompanying drawings.

FIG. 1 schematically shows a supercharging structure for an engine to which the present invention is applied. Intake air to be supplied to the engine 1 is sent from the air cleaner 5 through the intake passage 6 to the compressor section 7 of the supercharger 2 and is pressurized. It is supplied to the combustion chamber of the engine 1 via a passage 10.

A fuel injection valve 12 is provided in the intake passage 10 downstream of the throttle valve 11 . Exhaust gas from the engine 1 is supplied to the turbine section 14 of the supercharger 2 through an exhaust passage 13, and after releasing power for driving the compressor section 7, it passes through an exhaust passage 15 and a muffler 16 to the atmosphere. released. A variable nozzle 3 consisting of a large number of annularly arranged vanes is provided on the upstream side of the turbine section 14. By adjusting the opening degree of the variable nozzle 3 with an adjustment mechanism 4, the turbine section The flow rate of exhaust gas flowing into 14 can be controlled.

The adjustment mechanism 4 is controlled by an actuator 20,
As will be described later, this actuator 20 has a positive pressure chamber and a negative pressure chamber defined by two diaphragms, and these chambers are connected to a throttle valve via a conduit 18.19 having control valves 18a and 19a. The throttle valve 11 is connected to an intake passage 8 upstream of the throttle valve 11 and an intake passage 10 downstream of the throttle valve 11 . Furthermore, these control valves 18a and 19a are
Opening/closing is controlled by a control device °17 using engine rotational speed NO and throttle opening θth as parameters.

FIG. 2 shows an embodiment of an actuator according to the invention for driving the vanes described above. In FIG. 2, the actuator 20 is attached to the stay 21 with a screw 23.
The casing 22 has a cylindrical shape with a bottom fixed to the casing 22, and a cover 25 is caulked to the open end of the casing 22 so as to sandwich the peripheral edge of a diaphragm 26, which will be described later. Reference numeral 24 is a hose holder collinear with the casing 22. The casing 22 includes an outer cylindrical part 22a, an intermediate cylindrical part 22b, and an inner cylindrical part 22, which are coaxial with each other.
c, and an annular bottom wall 22d that connects the outer cylindrical part 22a and the intermediate cylindrical part 22b at the axial end on the side opposite to the cover 25, and an annular bottom wall 22d at the axial end on the cover 25 side. It has an inner annular bottom wall 22e that connects the intermediate cylindrical part 22b and the inner cylindrical part 22c.

The centers of the diaphragms 26 are held together by cup-shaped retainers 27 and 28 that open in directions away from each other, and at the centers of these retainers,
One end of the drive rod 29 is secured by a snap ring 30. A compression coil spring 31 is sandwiched between the outer annular bottom wall 22d and the retainer 28, and the diaphragm 26
is always urged toward the cover 25, that is, upward in FIG.

The stay 21 has an opening 32 that aligns with the inner circumferential surface of the intermediate cylindrical portion 22b, and the other end of the drive rod 29 protrudes from this opening 32.

Further, a sleeve-shaped bearing member 33 is sandwiched between the inner circumferential surface of the inner cylindrical portion 22c and the outer circumferential surface of the drive rod 29.
Moreover, it is fixed by a holder 34 press-fitted into the inner cylindrical portion 22c. A threaded portion 40 is provided near the free end of the drive rod 29, and when the lower end 35a of the bellows 35 is held by the holding members 36.
The lower end 35a of the bellows 35 is fixed to the stepped portion near the free end of the drive rod 29 by screwing the nut 39 into the threaded portion 40 through the bolt. This bellows 3
5 is a flexible type that is necessarily friction-free and is formed by cutting a cylindrical member made of fluororesin into an annular shape from the inside and outside. The other end of the bellows 35, that is, the L end 35b in FIG.
It is fixed by a seal member 42 press-fitted into the inner peripheral surface of 2b.

Further, a through hole 43 is provided in the inner annular bottom wall 22e, and communicates a negative pressure chamber 45 formed by the diaphragm 26 and the casing 22 with the inside of the bellows 35. A negative pressure introducing nipple 47 is fitted into the casing 22 for communicating the negative pressure chamber 45 with the outside. The cover 25 has a nipple 4 for communicating a positive pressure chamber 46 formed between the cover 25 and the diaphragm 26 with the outside.
8 is inserted.

In this actuator, the positive pressure introduction nipple 48
When positive pressure is introduced toward the positive pressure chamber 46, the drive rod 29 is driven downward in FIG. 2 through the diaphragm 26 and against the spring force of the compression coil spring 31. . Further, when negative pressure is introduced into the negative pressure chamber 45 from the negative pressure introduction nipple 47, the drive rod 29 is similarly driven downward via the diaphragm 26. At this time, since the drive rod 29 is guided by the bearing member 33, smooth operation of the actuator is ensured.

Further, although the free end of the drive rod 29 protrudes outside the actuator, the bellows 35 is used to isolate the negative pressure chamber 45 from the atmosphere, but the negative pressure inside the negative pressure chamber 45 is lost. Even when there is no pressure difference acting on the bellows 35, no particular undesirable stress is exerted on the bellows 35, unlike in the prior art using a diaphragm. On the other hand, since the diaphragm 26 which is subjected to positive pressure is always subjected to positive pressure or negative pressure, wrinkles and twisting do not occur.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, a bellows may be used in place of the diaphragm 26 without departing from the concept of the present invention.

[Effects of the Invention] As described above, the present invention provides an actuator suitable for supercharging pressure control that has a compact structure, is highly durable, and can be operated by both positive pressure and negative pressure. It is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing a supercharging structure to which an actuator according to the present invention is applied. FIG. 2 is a detailed longitudinal sectional view of the actuator according to the invention shown in FIG. 1... Engine 2... Supercharger 3... Variable nozzle 4... Adjustment mechanism 5... Air cleaner
6...Intake passage 7...Compressor 8...
Intake passage 9...Intercooler 1o...Intake passage 11...Throttle valve 12...Injection valve 13...
Exhaust passage 14...Turbine section 15...Exhaust passage 16...Muffler 17...Control tlII device
18.19... Pipe lines 18a, 19a... Control valve

Claims (3)

[Claims] (1) A supercharging pressure control actuator that can be operated by either positive pressure or negative pressure, which includes a casing, a diaphragm that divides the casing into a negative pressure chamber and a positive pressure chamber, and a a bellows separating the bellows from the atmosphere; and a drive rod coupled to both the diaphragm and the movable parts of the bellows, the axially inner end of the bellows comprising a fixed end fixed within a recess of the casing; An actuator for controlling supercharging pressure, characterized in that the movable portion has an outer end in the axial direction coupled to the drive rod. (2) The casing includes an outer cylindrical part, an intermediate cylindrical part, and an inner cylindrical part that are coaxially formed with each other, and the outer cylindrical part and the intermediate cylindrical part at the outer end in the axial direction of the casing. and an inner annular bottom wall that connects the inner cylindrical part and the intermediate cylindrical part at an axially inner end of the casing, and the fixed end of the bellows has a The supercharging pressure control actuator according to claim 1, wherein the actuator is received between the intermediate cylindrical part and the inner cylindrical part. (3) A guide portion for guiding movement of the drive rod in the axial direction is formed between the drive rod and the inner cylindrical portion, as set forth in claim 2. Actuator for boost pressure control.