JP4128269B2 - Variable form turbine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable geometry turbine incorporating a displaceable turbine inlet passage sidewall.
[0002]
[Prior art and its problems]
U.S. Pat. No. 5,522,697 discloses a known variable form turbine in which a turbine wheel is mounted for rotation about a predetermined axis in a housing. An inlet passage for the turbine wheel is defined between a fixed wall of the housing and a side wall that is displaceable relative to the fixed wall, whereby the width of the inlet passage is controlled. The side wall is supported on a rod that extends parallel to the axis of rotation of the housing, and the rod is configured to move axially relative to the housing, thereby controlling the position at which the side wall is applied. .
[0003]
The rod is displaced by a pneumatic actuator mounted on the outside of the housing, which drives the piston. The actuator piston is coupled to a lever that extends from a shaft that is pivotally supported by the housing, and thereby rotates the shaft through displacement of the lever. A yoke with two spaced arms is mounted on a shaft in a recess inside the housing. The edge of each arm of the yoke is received in a slot in the respective side wall support rod. Thus, when the actuator piston is displaced, the arm is pivoted, the side wall is driven in the axial direction, and as a result, the arm and the side wall support rod are engaged with each other.
[0004]
A variable form turbine is also disclosed in a co-pending application of the same priority date as this application, in which an external actuator mechanically coupled to the side wall is displaced by a piston and cylinder arrangement in the housing. It is configured as follows. Various problems have been experienced in the control of the axial position of the side wall, both with respect to the conventional external actuator device and with a device that relies on a piston and cylinder in the housing. In particular, it has been found that the side wall becomes difficult to control when it is approached to its fully closed position, i.e., the position where the width of the turbine inlet passage is minimized.
[0005]
Accordingly, an object of the present invention is to solve or reduce the above-described problems.
[0006]
SUMMARY OF THE INVENTION
In accordance with the present invention, the following variable form turbine is defined: a housing, a turbine wheel mounted for rotation on a predetermined axis in the housing, and a fixed wall and an annular side wall. A gas inlet passage for a turbine, mounted in the housing and displaceable relative to a fixed wall between first and second axially spaced positions, and a side wall from the fixed wall Controlling the axial position of the side wall by applying at least one spring biased away in the direction of the first position and applying an axial force against the side wall in a direction opposite to the at least one spring Wherein the at least one spring has a non-linear length characteristic with respect to the spring force and is thereby applied The combined force of the pulling force and the axial force applied to the side wall as a result of the gas flow through the passage is continuously increased as the side wall is displaced from the first position to the second position A variable form turbine is provided.
[0007]
The rate of change of the spring force associated with the displacement of the side wall can be increased as the side wall is displaced from the first position to the second position. The spring force is supplied by one or more springs, and each or each of them has a non-linear length characteristic with respect to the spring force, or is supplied by two or more springs, Each of them has a linear length characteristic with respect to the spring force, but the combined spring combined force can be configured to be non-linear.
[0008]
The side wall can be mounted on a support rod that extends parallel to the axis of the wheel, and this support rod is acted directly on by or on its or each spring. It can be coupled to an external actuator that is incorporated.
[0009]
【Example】
Next, one embodiment of the present invention will be described below as an example with reference to the accompanying drawings.
[0010]
Referring to FIGS. 1 and 2, the illustrated variable form turbine includes a housing defined by a bearing housing 1 and a turbine wheel housing 2 clamped by an annular clip 3 and a shaft 5 for rotation about an axis 6. And a turbine wheel 4 mounted thereon. The shaft 5 is supported on a bearing in the bearing housing 1. The turbine housing 2 defines a surface 7 that faces a surface 8 defined by the side wall 9. The side wall 9 in the illustrated assembly is formed in a generally C-shaped cross section from a relatively thin steel material, but it will be understood that this side wall 9 can be composed of, for example, a cast part. . A vane 10 mounted on the side wall projects from the face 8 into an annular recess 11 defined in the housing. The side walls supporting the vanes in the illustrated embodiment are often referred to as “nozzle rings”, but the term “side walls” is used herein.
[0011]
A seal ring 12 regulates gas flow between an inlet passage 13 defined between the surfaces 7 and 8 and a chamber 14 located on the side of the side wall remote from the vane 10. That is, the side wall 9 forms an annular piston that is received within an annular cylinder defining the chamber 14. A support rod 15 to which the side wall 9 is attached extends into the chamber 14. An inlet 16 is formed in the bearing housing 1 so that the pressure in the housing 14 can be controlled. When the pressure increases, the side wall 9 is moved toward the fully closed position shown in FIG. 1, while when the pressure decreases, the side wall 9 is moved toward the fully open position shown in FIG.
[0012]
Referring to FIG. 3, there is shown one device for the spring loaded support rod 15 in the bearing housing 1. In the device shown in FIG. 3, which corresponds to the side wall 9 shown in FIGS. 1 and 2 in the fully open position, each support rod passes through a hole in the bearing housing 1 and into the recess 17. Has been extended. The recess 17 is defined between the bearing housing 1 and another housing element 18 coupled to the bearing housing 1. The pressure in the recess 17 is maintained close to the atmospheric pressure.
[0013]
The pressure in the chamber 14 is used to control the axial displacement of the side wall 9. Means (not shown) are provided for controlling the pressure in the chamber 14-according to a control program corresponding to, for example, engine speed and torque, and turbine pressure and temperature. The pressure control means is connected to the inlet 16.
[0014]
The rod 15 has a compression spring 19 having a linear spring force characteristic—which is compressed between the bearing housing 1 and a washer 20 held on one end edge of the rod 15- Is biased to the left. Therefore, if the inlet passage 13 and the chamber 14 are open to the atmosphere, the rod 15 will be positioned in the axial position shown in FIG. If the pressure in the chamber 14 is then increased, the rod 15 and the side wall 9 will be displaced to the right in FIG. 3 by a distance corresponding to the applied pressure.
[0015]
Reference is now made to FIG. 4, which shows an embodiment of the present invention, and elements equivalent to those shown in FIG. 3 are given the same reference numerals, however, as shown in FIG. It is noted that in the device, a further compression spring 21—having the same axis as the axis 6—is in contact with the annular support ring 22—which performs the same function as the washer 20 of the device shown in FIG. It will be. Each support rod 15 also extends through a compression spring 19 of the same axis. Therefore, the force for driving the rod 15 to the left in FIG. 4 is the combined force of the compressive force applied by the springs 19 and 21 and the axial force applied to the side wall 9 by the gas flowing in the inlet passage 13. Become.
[0016]
The springs 19 and 21 are configured so that the restoring force applied to the rod 15 is increased as the surface 8 of the side wall 9 approaches the surface 7 defined by the turbine housing 2. For example, the length of the spring 21 when relaxed can be set to a length that does not oppose the movement of the ring 22 to the right side of the drawing except when the side wall 9 is relatively close to the surface 7. . This means that the pressure in the inlet passage 13—which acts on the surface 8—is reduced when the surface 8 is close to the surface 7—the flow in the gap defined between these surfaces. Due to the conditions-in some cases it has been found to be advantageous properties.
[0017]
FIG. 5 shows a device as described with respect to FIG. 3—where the spring 19 has a linear spring rate—and the device according to the invention shown in FIG. 4—where the combination of springs 19 and 21 is non-linear. It shows the operational difference between generating a spring rate. In FIG. 5, the curve shows the side walls when the spacing between the faces 7 and 8 (width of the inlet passage) is increased from a minimum of 23 (fully closed as shown in FIG. 1) to a maximum of 24 (fully opened as shown in FIG. 2). 9 represents the axial force applied to the element assembly including 9.
[0018]
Curve 25 in FIG. 5 represents the change in axial force due to the reaction gas on the surface 8 of the side wall 9. It will be noted that as the passage width decreases, the reaction gas force initially increases continuously but then decreases as the side wall 9 approaches the turbine face 7. Curves 26 and 27 represent the force applied by spring 19 of FIG. Curves 28 and 29 represent the resultant axial force on the sidewall 9, which is reduced as the passage width decreases beyond the spacing indicated by line 30. Thus, in the device shown in FIG. 3, where the spring 19 has a linear characteristic, the axial position of the sidewall 9 becomes unstable when the inlet passage width decreases to the limit represented by the line 30. In particular, as soon as the side wall passes through the position represented by line 30, this side wall will tend to move rapidly out of control towards the position of minimum width.
[0019]
In the apparatus shown in FIG. 4, the spring 21 is not actuated when the width of the inlet passage is in the range represented by the distance between the lines 24 and 25. However, as soon as the passage width is reduced to the limit represented by line 31, further reductions in the passage width compress both spring 21 and spring 19. As a result, the characteristics of the combination spring are represented by lines 26 and 32, and the resultant force is represented by lines 28 and 33. That is, the combined force of the spring and reactant gas is continuously increased as the inlet passage width is reduced to the minimum width represented by line 23. Therefore, the instability of the axial position of the side wall 9 is eliminated.
[0020]
Referring to FIG. 6, this shows a cross-sectional view of an external actuator assembly having a conventional structure--except that a conventional compression spring having linear characteristics has been changed to a compression spring having non-linear characteristics. It is shown. A mechanism for interconnecting the actuator shown in FIG. 6 to a control rod as shown in FIGS. 1 to 4 is disclosed in, for example, US Pat. No. 5,522,695.
[0021]
Referring to FIG. 6, the lower half of this figure shows the actuator in its fully extended state (cooperating side walls correspond to the fully closed position as shown in FIG. 1), while FIG. The upper half shows the actuator in the fully retracted position (corresponding to the position where the cooperating side walls are fully closed as shown in FIG. 2). The actuator has a cover made of a press element 35 made of steel, and the peripheral edge of the diaphragm 36 is clamped between the covers. In FIG. 6, a chamber 37 is shown on the left hand side of the diaphragm 36, and pressure gas is introduced into the chamber from an inlet (not shown), thereby causing a cup-shaped member 39-the member to be a diaphragm. The axial movement of the actuator output rod 38, which is connected to the opposite side of the chamber 36 on the side away from the chamber 37, is controlled. The compression spring 40 is received in the cover, and one end thereof is brought into contact with the piston member 39 and the other end is brought into contact with the clamp plate 41, and the stud 42 extends from the clamp plate. The stud is provided with appropriate means for fixing the actuator to a support (not shown). The dust shield 43 prevents entry of contaminants into the cover.
[0022]
In a normal actuator, the compression spring 40 has a spring force that is linear with respect to the length relationship, so the same control problem as described with reference to the structure shown in FIG. 3 in FIG. 5 is raised. However, in the actuator according to the present invention shown in FIG. 6, the compression spring 40 has a non-linear characteristic, so that the same performance as that exhibited by the spring device shown in FIG. 4 is provided. Such a non-linear spring characteristic is appropriately formed in a usual manner, for example, by forming the compression spring 40 so that its one end spring winding is brought into contact with each other before the other end spring winding. Can be achieved. It will be appreciated that other devices may be contemplated, for example, a generally conical compression spring rather than the cylindrical shape shown in FIG.
[0023]
Further, as described above, in an alternative embodiment of the present invention, two or more springs—these springs are combined, each having a linear length characteristic with respect to the spring force. And configured to generate a non-linear spring force. Two of such springs can be configured, for example, such that one is housed inside the other, or these end edges are separated and connected by a suitable support such as a single plate. it can. Other possible devices will be readily understood by those skilled in the art as appropriate.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the upper half of a side wall assembly of a variable form turbine, where the side wall is shown in a position where the gas inlet passage is at its minimum width.
FIG. 2 is a cross-sectional view showing the lower half of the side wall assembly shown in FIG. 1—however, the side walls are displaced to the fully open position.
3 is a cross-sectional view showing a spring device for the side wall support rod shown in FIGS. 1 and 2. FIG.
4 is a cross-sectional view showing a spring device according to the present invention for the side wall support rod shown in FIGS. 1 and 2. FIG.
FIG. 5 is a schematic illustration showing another characteristic of the spring assembly shown in FIGS. 3 and 4 and the reactive and combined forces on the sidewall having such an assembly.
FIG. 6 is a cross-sectional view showing an external actuator assembly for a side wall support rod, where the actuator has been modified in accordance with the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Bearing housing 2 Turbine wheel housing 3 Annular clip 4 Turbine wheel 5 Axis 6 Axes 7, 8 Surface 9 Side wall 10 Vane 11 Annular recessed part 12 Seal ring 13 Inlet passage 14 Chamber 15 Support rod 16 Inlet 17 Recessed part 18 Housing elements 19, 21 Compression spring 20 Washer 22 Annular support ring 23 Minimum interval 24 Maximum interval 25, 26, 27, 28, 29, 32, 33 Curve (Line)
30, 31 spacing 35 elements (cover)
36 Diaphragm 37 Chamber 38 Output rod 39 Cup-shaped member (piston member)
40 Compression spring 41 Clamp plate 42 Stud 43 Dust shield

Claims (7)

A gas inlet passage for a turbine defined between a housing, a turbine wheel mounted for rotation on a predetermined axis in the housing, and a fixed wall and an annular side wall, mounted in the housing A gas inlet passage displaceable relative to the fixed wall between first and second axially spaced positions and at least one biasing the side wall away from the fixed wall toward the first position A variable form turbine comprising: a spring; and means for controlling an axial position of the side wall by applying an axial force against the side wall in a direction opposite to the at least one spring.
The at least one spring has a non-linear length characteristic with respect to the spring force, whereby a combined force of the applied spring force and the axial force applied to the side wall as a result of gas flow through the passage. A variable form turbine characterized in that the sidewall is continuously increased as the side wall is displaced from the first position to the second position.   The variable form turbine according to claim 1, wherein the rate of change of the spring force accompanying the displacement of the side wall is increased as the side wall is displaced from the first position to the second position.   The variable form turbine of claim 2 including one or more springs, each having a non-linear length characteristic with respect to the spring force.   Comprising at least two springs, each of which has a linear length characteristic with respect to the spring force, and that these springs are configured such that their resultant force applied to the sidewalls is non-linear. The variable form turbine according to claim 2.   The side wall is mounted on a support rod that extends parallel to the axis of the wheel, and each support rod is inserted and acted upon by a respective compression spring. A variable form turbine according to claim 1.   The variable form turbine according to claim 5, wherein each support rod is further acted by a compression spring having the same axis as the wheel axis.   Side walls are mounted on support rods that extend parallel to the axis of the wheel, each support rod being acted upon by a mechanism coupled to an actuator mounted on the outside of the housing, the at least one spring described above and 4. A variable form turbine according to claim 1, wherein the means for applying the axial force is defined by an actuator.

Images