JPH11343857A - Actuator for turbocharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold an opening/closing valve to open at a small opening degree by providing a supporting member movably supporting a connecting member connected to an opening/closing valve of a turbocharger, and restraining movement of the connecting member by an energizing means when the opening quantity of the opening/closing valve is under a specified value. SOLUTION: When the flow of exhaust gas flowing in an exhaust side turbine wheel is smaller than the prescribed flow, the opening quantity of a cutoff valve 37 is increased by an ECU, and the intake air negative pressure in an intake passage 35 is introduced in the negative pressure chamber 32 of an actuator 24. Hereby a diaphragm 38 is driven, the opening/closing valve is closed around pivotal shafts 13 through a rod 26 and a connecting arm 25, and the exhaust gas flow flowing in the turbine wheel is increased. In this case, only while the opening quantity of the opening/closing valve 10 is relatively small, a plate spring 42 provided on the end part of the rod 26 is engaged with an engaging plate 44 provided on a housing 27, and by energizing the plate spring 42, movement of the rod 26 toward a housing bottom face 40 is restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a turbocharger actuator.

[0002]

2. Description of the Related Art Turbochargers are known for drawing a larger amount of air into a cylinder of an internal combustion engine. The turbocharger includes an exhaust turbine wheel disposed in an exhaust passage of the internal combustion engine and an intake turbine wheel disposed in an intake passage of the internal combustion engine. The exhaust-side turbine wheel and the intake-side turbine wheel are connected to each other by a shaft. When the exhaust-side turbine wheel is rotated by the exhaust passage flowing in the exhaust passage, the intake-side turbine wheel is rotated via the shaft. When the intake-side turbine wheel rotates, air flowing in the intake passage is compressed. For this reason, a larger amount of air is introduced into the cylinder.

In the above turbocharger, the rotation speed of the exhaust-side turbine wheel varies depending on the flow rate of exhaust gas passing through the exhaust-side turbine wheel. Therefore, when the flow rate of the exhaust gas is small, the rotation speed of the exhaust-side turbine wheel is low, and the air is not sufficiently compressed in the intake-side turbine wheel. Therefore, in the turbocharger disclosed in Japanese Patent Application Laid-Open No. 63-156429, a pivotable on-off valve is provided around the exhaust-side turbine wheel, and a flow path (nozzle) having a variable flow area is formed between these on-off valves. When the flow rate of the exhaust gas is low, the on-off valve is closed to narrow the flow path, increase the flow rate of the exhaust gas, increase the rotation speed of the exhaust-side turbine wheel, and sufficiently compress the air in the intake-side turbine wheel. ing.

Japanese Patent Application Laid-Open No. 63-156429 discloses a technique for braking engine operation by using an on-off valve (hereinafter, exhaust braking). Specifically, the engine operation is braked by fully closing the on-off valve to prevent exhaust gas from flowing downstream of the on-off valve.

[0005]

However, when the on-off valve is fully closed, no intake air is introduced into the cylinder of the internal combustion engine, and the operation of the engine is stopped. Therefore, it is necessary to keep the on-off valve slightly open when performing exhaust braking. However, in Japanese Patent Application Laid-Open No. 63-156429, since the actuator is operated linearly by air pressure, it is difficult to keep the on-off valve slightly opened. Further, if a control device such as an electronic control device is provided to keep the on-off valve slightly opened, not only the structure of the actuator itself becomes complicated, but also the manufacturing cost of the actuator increases. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an actuator capable of maintaining a slightly open state of an on-off valve for controlling the flow rate of exhaust gas flowing into an exhaust-side turbine wheel in a simple manner.

[0006]

According to the present invention, there is provided an exhaust turbine wheel disposed in an exhaust passage of an internal combustion engine, the exhaust turbine wheel being connected to the exhaust turbine wheel and being connected to the exhaust turbine wheel. An exhaust-side turbine wheel disposed in an intake passage; and an on-off valve disposed in an exhaust passage upstream of the exhaust-side turbine wheel to control a flow rate of exhaust gas flowing into the exhaust-side turbine wheel. An actuator for opening and closing the on-off valve of the turbocharger, comprising: a connecting member connected to the on-off valve; and a support member for movably supporting the connecting member, wherein the on-off valve is adapted to displace the connecting member. One of the connecting member and the supporting member has an urging means, and the opening amount of the on-off valve is set to a value smaller than a predetermined opening amount. The other of the connecting member and the supporting portion is engaged with the biasing means to urge said urging means when again. Therefore, when the opening amount of the on-off valve is smaller than the predetermined opening amount, the movement of the connecting member is suppressed by the urging means.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 shows a turbocharger 1 according to a first embodiment of the present invention. The turbocharger 1 includes an exhaust-side turbine wheel 2 and an intake-side turbine wheel 3 (FIG. 2).
Reference). As shown in FIG. 2, the exhaust-side turbine wheel 2 and the intake-side turbine wheel 3 are connected to each other by a shaft 4. Exhaust side turbine wheel 2
Is an exhaust side space 6 formed in the turbocharger body 5
Is placed within. On the other hand, the intake-side turbine wheel 3 is disposed in an intake-side space 7 formed in the turbocharger main body 5. In the turbocharger main body 5, a substantially annular exhaust supply passage 8 for flowing exhaust gas to be supplied to the exhaust-side turbine wheel 2 is formed. The exhaust gas supply path 8 is formed around the exhaust-side turbine wheel 2 so as to cover the outer periphery thereof.

As shown in FIG. 1, the upstream end of the exhaust passage 8 is connected to the downstream end of the exhaust passage 9. An upstream end of the exhaust passage 9 is connected to a downstream end of an exhaust passage (not shown) connected to a cylinder of the internal combustion engine. Therefore, the exhaust gas discharged from the internal combustion engine is supplied to the exhaust side turbine wheel 2 through the exhaust passage, the exhaust passage 9 and the exhaust supply passage 8 in this order. When the exhaust gas is supplied to the exhaust-side turbine wheel 2, the exhaust-side turbine wheel 2 is rotated. At this time, the intake-side turbine wheel 3 connected to the exhaust-side turbine wheel 2 via the shaft 4 is rotated. The air to be introduced into the cylinder of the internal combustion engine is compressed by the rotation of the intake-side turbine wheel 3. In this way, the amount of intake air introduced into the cylinder of the internal combustion engine is increased by the turbocharger 1.

As shown in FIG. 1, a plurality of on-off valves 10 are mounted on a support board 11 at a certain interval in the circumferential direction around the exhaust-side turbine wheel 2 and in the exhaust supply passage 8. These on-off valves 10 are pivotally attached to a support board 11. The support board 11 is annular and is inserted into an opening formed on the back surface of the turbocharger main body 5 and forms a part of the turbocharger main body 5. A flow path (nozzle) 12 is formed between the on-off valves 10. The on-off valve 10 is attached to the support plate 11 such that a slight gap is formed between the wall surface of the turbocharger main body 5 forming the exhaust gas supply passage 8 and one side of the on-off valve 10. On-off valve 1
Reference numeral 0 is attached to the support board 11 such that a slight gap is also formed between the wall surface of the support board 11 and the other side of the on-off valve 10.

When the on-off valve 10 is pivoted, these nozzles 12
Of the flow path changes. The pivoting of these on-off valves 10 is controlled according to the flow rate of the exhaust gas supplied to the exhaust-side turbine wheel 2 as described later.

The on-off valve 10 is connected to the support board 1 via a pivot shaft 13.
1 (see FIG. 3). As shown in FIG. 3, the pivot shaft 13 passes through the support
And protrudes from the back surface of the support board 11. The pivot shaft 13 is fixed to one end of a pivot arm 14 for pivoting the on-off valve 10 so as not to pivot with respect to the pivot arm 14 as described later. The other end of the pivot arm 14 has a forked portion 15.

As shown in FIG. 2 and FIG.
A generally annular pivot ring 17 pivotable about an axis A of the shaft 4 is disposed in a space 16 formed therein. The pivot ring 17 is pivotally supported by a support roller 18 with respect to the support plate 11. The support roller 18 is a support plate 11
And a shaft portion 2 fixed to a lid 19 covering the support board 11
0 and a roller portion 21 rotatable on the shaft portion 20. The outer peripheral surface of the roller portion 21 is
Contacts the inner peripheral surface of

The pivot ring 17 is provided with projections 22 at regular intervals in the circumferential direction. The forked portion 15 of the pivot arm 14 engages with the projection 22 so as to sandwich the projection 22. Note that the forked portion 15 is not fixed to the projection 22 and can slide with respect to the projection 22. Also pivot ring 1
7, a driving projection 23 for driving the pivot ring 17 is formed as described later. The driving projection 23 is connected to the actuator 24 as shown in FIGS.

As shown in FIG. 4, the actuator 24 includes a generally cylindrical rod 26 connected to the pivot ring 17 via a connecting arm 25, and a housing 27 for supporting the rod 26. The connecting arm 25 has a generally oblong opening 28 at each end. The driving projections 23 of the pivot ring 17 and the driving projections 29 of the rod 26 are inserted into these openings 28, respectively. In the first embodiment, the rod 26 corresponds to a connecting member connected to the on-off valve 10, and the housing 27 corresponds to a supporting member for supporting the rod 26.

The rod 26 includes a generally circular actuation plate 30 within a housing 27. The inside of the housing 27 is divided into an atmospheric pressure chamber 31 and a negative pressure chamber 32 by an operation plate 30. The atmospheric pressure chamber 31 is opened to the atmosphere through an atmosphere hole 33. On the other hand, the negative pressure chamber 32 is connected to an intake passage 35 of the internal combustion engine via a negative pressure introducing pipe 34. The negative pressure introducing pipe 34 is connected to the intake passage 35 on the downstream side of the throttle valve 36 disposed in the intake passage 35. The negative pressure introducing pipe 34 is provided with a shutoff valve 37. When the shutoff valve 37 is closed, the negative pressure introduction pipe 34 is shut off, and the negative pressure in the intake passage 35 is not introduced into the negative pressure chamber 32. On the other hand, when the shutoff valve 37 is opened, the negative pressure in the intake passage 35 is introduced into the negative pressure chamber 32. The shutoff valve 37 is connected to an electronic control unit (ECU), and the opening and closing operation of the shutoff valve 37 is controlled by the electronic control unit as described later. In the first embodiment, when the opening amount of the shutoff valve 37 is changed linearly, the negative pressure introduced into the negative pressure chamber 32 is also changed linearly.

The operating plate 30 is attached to the housing 27 via a diaphragm 38. Further, the operation plate 30 is urged by a coil spring 39 as urging means. The coil spring 39 is disposed between the operation plate 30 and the bottom surface 40 of the housing 27, and urges the operation plate 30 to close the on-off valve 10.

Next, control of the opening / closing operation of the on-off valve 10 in the first embodiment will be described. When the flow rate of the exhaust gas flowing into the exhaust side turbine wheel 2 is smaller than a predetermined flow rate, the opening amount of the shut-off valve 37 is increased by the electronic control unit, and a larger negative pressure is introduced into the negative pressure chamber 32. The rod 26 is drawn into the actuator 24 by the negative pressure introduced into the negative pressure chamber 32. When the rod 26 is retracted into the actuator 24, the connecting arm 25
It is pivoted around one. The pivoting of the connecting arm 25 causes the pivoting ring 17 to pivot via the driving projection 23. The pivoting of the pivoting ring 17 causes the pivoting shaft 23 to pivot via the pivoting arm 14 so that the on-off valve 1
0 is closed. Thus, the flow rate of the exhaust gas flowing into the exhaust-side turbine wheel 2 is increased.

On the other hand, when the flow rate of the exhaust gas flowing into the exhaust-side turbine wheel 2 is larger than a predetermined flow rate, the opening amount of the shut-off valve 37 is reduced by the electronic control unit,
The negative pressure introduced into the negative pressure chamber 32 is reduced. When the negative pressure in the negative pressure chamber 32 decreases, the operating plate 30 is urged by the coil spring 39 so that the rod 26
From the housing 27. When the rod 26 extends from the housing 27, the connecting arm 25 is pivoted about its pivot axis 41. The pivoting of the connecting arm 25 causes the pivoting ring 17 to pivot via the driving projection 23. The pivoting of the pivot ring 17 causes the pivot shaft 23 to pivot via the pivot arm 14 so that
The on-off valve 10 is opened. Therefore, the flow rate of the exhaust gas flowing into the exhaust-side turbine wheel 2 is reduced.

Thus, in the first embodiment, the flow rate of the exhaust gas flowing into the exhaust-side turbine wheel 2 is maintained at a predetermined flow rate.

In the first embodiment, as shown in FIG. 5, a leaf spring 42 is provided as a biasing means on the peripheral surface of the end of the rod 26 located in the housing 27. Leaf spring 42
Is attached at one end to the peripheral surface of the end of the rod 26,
The center is bent to form a convex portion 43. The top of the convex portion 43 is located radially outward with respect to the rod axis B from the end of the leaf spring 42 attached to the end of the rod 26. In the first embodiment, two leaf springs 42 are provided symmetrically with respect to the rod axis B.

On the other hand, two engagement plates 44 suitable for engaging with the respective leaf springs 42 are attached to the housing bottom surface 40 where the circular end surface of the rod 26 located in the housing 27 faces. The engagement plate 44 has a vertical portion 45 extending from the bottom surface 40 in a direction perpendicular to the housing bottom surface 40, and a horizontal portion 46 extending from the end of the vertical portion 45 in a direction perpendicular to the vertical portion 45. When the engaging plate 44 is not engaged with the leaf spring 42, the end of the horizontal portion 46 facing the leaf spring 42 is radially inward with respect to the rod axis B from the top of the convex portion 43 of the leaf spring 42. To position. The vertical portion 45 is located radially outward with respect to the rod axis B from the top of the convex portion 43 of the leaf spring 42.

The engagement plate 44 engages with the leaf spring 42 only while the opening amount of the on-off valve 10 is relatively small, and urges the leaf spring 42.
Is suppressed. On the other hand, when the rod 26 moves toward the housing bottom surface 40 and the horizontal portion 46 of the engagement plate 44 exceeds the convex portion 43 of the leaf spring 42, the rod 26
Quickly moves toward the housing bottom surface 40, and the engagement plate 44 is quickly disengaged from the convex portion 43. Therefore, when the rod 26 further moves toward the housing bottom surface 40, the engagement plate 44 does not engage with the leaf spring 42,
The movement of the rod 26 toward the housing bottom surface 40 is not suppressed.

Accordingly, in the first embodiment, as shown in FIG. 6, while the negative pressure introduced into the negative pressure chamber 32 rises from zero to a predetermined first pressure P1, the opening amount of the on-off valve 10 is increased. Increases from zero to the first valve opening amount A1. During this time, the rate of increase of the opening amount of the on-off valve 10 with respect to the rate of increase of the negative pressure is relatively small because the leaf spring 42 and the engagement plate 44 are engaged and the movement of the rod 26 toward the housing bottom surface 40 is suppressed. small. The negative pressure is a predetermined first pressure P
When the value exceeds 1, the horizontal portion 46 of the engagement plate 44 gets over the convex portion 43 of the leaf spring 42, so that the opening amount of the on-off valve 10 is stepped from the first opening amount A1 to the second opening amount A2. Increase. The negative pressure is a predetermined first pressure P
While increasing from 1 to a predetermined second pressure P2, the opening amount of the on-off valve 10 increases from the first opening amount A2 to the third opening amount A3. During this time, the rate of increase in the opening amount of the on-off valve 10 with respect to the rate of increase in the negative pressure is determined by
Is relatively large because the movement of the rod 26 toward is not suppressed. When the negative pressure reaches a predetermined second pressure P2, the opening amount of the on-off valve 10 reaches the maximum value A3, so that the negative pressure exceeds the second pressure P2. Also, the opening amount of the on-off valve 10 does not increase beyond the third opening amount A3 which is the maximum value.

Therefore, according to the first embodiment, the negative pressure chamber 3
Shut-off valve 37 for linearly controlling the value of the negative pressure introduced into
It is easy to maintain the opening amount of the on-off valve 10 at a relatively small value in the actuator 24 provided with. Further, since the vertical portion 45 is located radially outward with respect to the rod axis B from the top of the convex portion 43 of the leaf spring 42, the vertical portion 45 becomes flat after the horizontal portion 46 has passed over the convex portion 43 of the leaf spring 42. Engagement with the spring 42 is prevented.

When the throttle valve 36 is closed, the negative pressure in the intake passage 35 downstream of the throttle valve 36 increases. At this time, the amount of air introduced into the cylinder of the internal combustion engine decreases, and the amount of exhaust gas discharged from the cylinder also decreases. On the other hand, when the throttle valve 36 is closed and the negative pressure in the intake passage 35 downstream of the throttle valve 36 increases, the increased negative pressure is introduced into the negative pressure chamber 32. Therefore, on-off valve 1
0 is closed. Therefore, according to the first embodiment, when the opening amount of the shut-off valve 37 is kept constant, the intake air amount decreases, and as a result, when the exhaust gas amount decreases, the on-off valve 10 is automatically closed. The flow rate of the exhaust gas that is valved and supplied to the exhaust-side turbine wheel 2 is increased.

When the turbocharger main body 5 and the support plate 11 forming the exhaust supply passage 8 thermally expand due to the heat of the exhaust gas, the exhaust supply passage 8 becomes narrow. Therefore, the on-off valve 10, the wall surface of the turbocharger main body 5, and the support plate 1
Even if a gap is formed between the open / close valve 10 and the
May be unable to pivot. Therefore, in the first embodiment, a substantially cylindrical spacer 47 is provided between the wall surface of the turbocharger main body 5 and the wall surface of the support board 11 which form the exhaust supply passage 8.
Is inserted. The spacer 47 is fixed to the turbocharger main body 5 and the support board 11 by a shaft 48. The generally circular one end surface of the spacer 47 contacts the wall surface of the turbocharger main body 5, and the substantially circular other end surface of the spacer 47 contacts the wall surface of the support board 11. Therefore, thermal expansion of the wall of the turbocharger main body 5 and the wall of the support board 11 due to the heat of the exhaust gas is suppressed by the spacer 47. The exhaust gas that has passed through the exhaust-side turbine wheel 2 has an exhaust gas discharge port 49.
Through the exhaust passage 50 on the downstream side of the turbocharger 1.

Next, a turbocharger according to a second embodiment of the present invention will be described. In the first embodiment, when the negative pressure introduced into the negative pressure chamber 32 reaches a predetermined first pressure P1, the opening amount of the on-off valve 10 increases stepwise. Therefore, the flow rate of the exhaust gas flowing into the exhaust side turbine wheel 2 decreases stepwise, and the amount of air supplied to the cylinder of the internal combustion engine changes stepwise. Therefore, the output of the internal combustion engine changes stepwise, which is not preferable. Therefore, in the second embodiment, the opening amount of the on-off valve 10 is prevented from changing stepwise.

As shown in FIG. 7, in the second embodiment, a conical portion (hereinafter, referred to as a tapered portion) tapering toward the tip of the rod 26 is provided on the peripheral surface of the end of the rod 26 located in the housing 27.
A conical portion 51 is formed. On the other hand, the housing bottom surface 40
Is mounted with two engagement plates 52 extending from the bottom surface 40 substantially perpendicular to the bottom surface 40, but inclined inward in the radial direction with respect to the rod axis B. These engagement plates 52 can be displaced radially outward with respect to the rod axis B about a mounting portion 53 between the engagement plate 52 and the housing bottom surface 40. When the engaging plate 52 is not engaged with the conical surface of the conical portion 51, the end of the engaging plate 52 facing the conical surface of the conical portion 51 is connected to the rod 26.
Is located radially inward with respect to the rod axis B with respect to the cylindrical surface of. The mounting portion 53 is located at the same position as the circumferential surface of the rod 26 in the radial direction with respect to the rod axis B.

The engagement plates 52 are engaged with the conical surface of the conical portion 51 only while the opening amount of the on-off valve 10 is relatively small, and spread radially outward with respect to the rod axis B while moving toward the housing bottom surface 40. 26 is suppressed.
On the other hand, when the rod 26 moves toward the housing bottom surface 40 and the engagement plate 52 engages with the cylindrical surface 54 of the rod 26, the movement of the rod 26 toward the housing bottom surface 40 is not suppressed.

Therefore, in the second embodiment, as shown in FIG. 8, while the negative pressure introduced into the negative pressure chamber 32 rises from zero to a predetermined third pressure P3, the opening amount of the on-off valve 10 is increased. Increases from zero to the fourth valve opening amount A4. During this time, the rate of increase in the valve opening amount of the on-off valve 10 with respect to the rate of increase in the negative pressure is because the conical surface of the conical portion 51 and the engagement plate 52 are engaged and the movement of the rod 26 toward the housing bottom surface 40 is suppressed. , Relatively small. While the negative pressure rises from the third predetermined pressure P3 to the fourth predetermined pressure P4, the opening amount of the on-off valve 10 is changed from the fourth opening amount A4 to the fifth opening amount A5. To increase. During this time, the rate of increase of the valve opening amount of the on-off valve 10 with respect to the rate of increase of the negative pressure is determined by the following reason.
Relatively large. When the negative pressure reaches a predetermined fourth pressure P4, the opening amount of the on-off valve 10 reaches the maximum value A5, so that the negative pressure becomes the predetermined fourth pressure P4.
Even if it exceeds 4, the opening amount of the on-off valve 10 does not increase beyond the fifth value A5, which is the maximum value.

Therefore, according to the second embodiment, the negative pressure chamber 3
Shut-off valve 37 for linearly controlling the value of the negative pressure introduced into
In the actuator 24 having the above, the opening amount of the on-off valve does not change stepwise. The configuration and operation and effect of the second embodiment other than those described above are the same as those of the first embodiment, and a description thereof will be omitted.

[0032]

According to the present invention, when the opening amount of the on-off valve is smaller than the predetermined opening amount, the movement of the connecting member is suppressed by the urging means. Therefore, when the opening amount of the on-off valve is smaller than the predetermined opening amount, it becomes easy to maintain the opening amount of the on-off valve at a value smaller than the predetermined opening amount.

[Brief description of the drawings]

FIG. 1 is a perspective view of a turbocharger according to a first embodiment of the present invention in which some components are omitted.

FIG. 2 is a longitudinal sectional view of the turbocharger according to the first embodiment, which is a sectional view taken along line II-II in FIG.

FIG. 3 is a plan view along a line III-III in FIG. 2;

FIG. 4 is a cross-sectional view of the actuator according to the first embodiment.

FIG. 5 is a view showing the rod end of the actuator of the first embodiment in detail.

FIG. 6 is a graph showing a relationship between a negative pressure introduced into a negative pressure chamber and an opening amount of an on-off valve according to the first embodiment.

FIG. 7 is a view showing in detail a distal end of a rod of an actuator according to a second embodiment.

FIG. 8 is a graph showing a relationship between a negative pressure introduced into a negative pressure chamber and an opening amount of an on-off valve according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Turbocharger 2 ... Exhaust side turbine wheel 3 ... Intake side turbine wheel 10 ... Open / close valve 24 ... Actuator 26 ... Rod 42 ... Leaf spring 44, 52 ... Engagement plate 51 ... Conical surface

Claims (1)

[Claims] An exhaust turbine wheel disposed in an exhaust passage of an internal combustion engine, an intake turbine wheel connected to the exhaust turbine wheel and disposed in an intake passage of the internal combustion engine, and the exhaust turbine wheel. An on-off valve disposed in an exhaust passage upstream of the exhaust-side turbine wheel to control the flow rate of exhaust gas flowing into the exhaust gas turbine. And a support member movably supporting the connection member, wherein the on-off valve is opened and closed according to the displacement of the connection member, and one of the connection member and the support member is Having an urging means, when the opening amount of the on-off valve is smaller than a predetermined opening amount, the other of the connecting member and the supporting portion is An actuator for a turbocharger, wherein said actuator is engaged with said urging means so as to urge said urging means.