JPH10184371A - Turbocharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with an EGR valve of an external piping and reduce passage resistance by partitioningly forming an EGR passage inside a compressor, opening an outlet of the EGR passage onto an impeller outlet, and arranging an EGR valve body on the outlet of the EGR passage. SOLUTION: An EGR passage 9 is partitioningly formed inside a center housing 2 of a compressor part of a turbocharger. The EGR passage 9 is partitioned from a diffuser 4 by means of a seal plate 7. The EGR passage 9 is composed of a tubular part 10 forming an introduction part of exhaust gas, and a ring chamber 11 communicated with the tubular part 10 over all circumference. A ring plate 12 forming an EGR valve body is superposed on an axially rear side of the seal plate 7 slidably in a circumferential direction. The vicinity of a trailing edge 17 of an impeller 3 inside the diffuser 4 serves as an impeller outlet 18. An outlet hole 19 of the EGR passage 9 formed on the seal plate 7 is opened thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbocharger for an engine which enables EGR (exhaust gas recirculation).

[0002]

2. Description of the Related Art Generally, when performing EGR in an engine equipped with a turbocharger, as shown in FIG. 8, a part of exhaust gas (EGR gas) is taken out upstream of a turbine section b of a turbocharger a, and the exhaust gas is removed. EGR passage c
Through the intercooler e after being mixed with fresh air and sent to the engine f. In particular, the EGR passage c is provided with an external pipe connecting the exhaust passage g and the compressor d, and a compressor d.
And an internal passage defined inside. The outlet h of the internal passage preferably opens at the impeller outlet, which is the downstream side immediately adjacent to the impeller. The reason for this is that if the EGR gas is sent to the compressor section d, especially to the upstream side of the impeller, the impeller tends to corrode with the gas. On the other hand, if the EGR gas is sent to the downstream side of the compressor section d, This is because, when the supercharging pressure increases, the pressure difference reverses and EGR becomes impossible. Since the impeller outlet is a region where the pressure has not yet been sufficiently increased, if EGR gas is sent to this part,
The reverse phenomenon of the pressure difference can be prevented, and at the same time, the impeller corrosion can be prevented.

[0003]

Incidentally, it is necessary to control the EGR gas flow rate or the EGR rate optimally according to the engine operating condition determined by the conditions such as the engine speed, the engine load, and the acceleration / deceleration. For this reason, conventionally,
An EGR valve i is provided in a portion of the external pipe of the EGR passage c to control the flow rate.

[0004] The outlet h of the EGR passage c opened to the impeller outlet is specifically formed by a fixed slit.

However, with such a configuration, there are throttles at two places, the EGR valve h and the fixed slit, which increases the passage resistance, increases the pressure loss, and limits the EGR gas flow rate. Was gone.

[0006]

In the turbocharger according to the present invention, an EGR passage is defined inside a compressor section, an outlet of the EGR passage is opened to an impeller outlet, and an EGR passage is formed at an outlet of the EGR passage. And an EGR valve for opening and closing the EGR valve to control the EGR flow rate.

According to this, the EG inside the compressor section is
The EGR flow rate can be controlled by the R valve body, whereby the EGR valve of the external pipe can be eliminated and the passage resistance can be reduced.

[0008] Here, the outlet of the EGR passage is formed of an outlet hole formed in a seal plate, and the EGR valve body is a ring plate that is superimposed on the seal plate and slidable in the circumferential direction. It may be made of a ring plate having a hole that can communicate with the outlet hole. Further, the outlet portion of the EGR passage may be formed of an outlet hole formed in a seal plate, and the EGR valve body may be formed of an opening / closing plate which can engage with the seal plate and slide in the radial direction.

[0009]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

[First Embodiment] FIG. 1 is a vertical sectional side view showing the inside of a compressor section of a turbocharger according to the present invention. Such a turbocharger is applied to, for example, a diesel engine. As shown, the compressor section has two housings fastened to each other, namely a compressor housing 1 and a center housing 2.
It consists of An impeller 3 is rotatably housed in the compressor housing 1, and a diffuser 4 is defined on an outer peripheral side or a radially outer side of the impeller 3, and the diffuser 4 is communicated with a scroll chamber 5. The diffuser 4 includes a shroud side wall portion 6 formed in the compressor housing 1 in the axial front (right side in FIG. 1) and a seal plate 7 fixed in the center housing 2 in the axial rear side, that is, the hub side (left side in FIG. 1). And is divided from

The seal plate 7 is formed in a ring shape and is fixed to the ring-shaped groove 8 of the center housing 2 by press fitting or the like. On the other hand, an EGR passage 9 is defined inside the center housing 2.
And the diffuser 4 are partitioned by a seal plate 7. The EGR passage 9 includes a tubular portion 10 connected to an external pipe (not shown) and forming an exhaust gas introduction portion, and a ring chamber 11 communicated with the tubular portion 10 and extending in the entire circumferential direction.

Further, a ring plate 12 is superposed slidably in the circumferential direction behind the seal plate 7 in the axial direction. As shown in FIG. 2, the ring plate 12 has a smaller outer diameter and the same inner diameter with respect to the seal plate 7,
The inner peripheral end surface slides on the inner peripheral surface 13 of the ring-shaped groove 8,
The outer peripheral end surface slides on the step surface 14 of the ring-shaped groove 8. Further, the ring plate 12 is formed of the seal plate 7 and the inner and outer peripheral bottom surfaces 1 of the ring-shaped groove 8.
5 and 16, it slides in the circumferential direction while its movement in the axial direction is restricted.

In particular, in the diffuser 4, the impeller outlet 18 is located immediately downstream of the impeller 3, that is, near the trailing edge 17 of the impeller 3 and downstream (in the radial direction) in the air flow direction. An outlet hole 19 formed in the seal plate 7 is opened at the site. This outlet hole 19 forms an exhaust gas outlet in the EGR passage 9. On the other hand, the ring plate 12 is provided with a hole portion 20 that can communicate with the outlet hole 19, whereby the ring plate 12 slides and rotates, so that the outlet hole 1
9 can be changed.

As shown in FIG.
And the hole 20 at the same position in the radial direction,
It is provided in places. The positions and numbers in the circumferential direction are not limited to the above. And the exit hole 19 and the hole 20 are
It is formed in the shape of an elongated slit along the circumferential direction and in the same shape. The hole 20 moves in the rotation direction with respect to the fixed outlet hole 19, and the four outlet holes 19 are simultaneously opened and closed so as to have the same opening area. The positions or dimensions of the outlet hole 19 and the hole 20 may be individually different in the circumferential direction, so that the opening areas of the outlet holes 19 and the holes 20 are different.

In this manner, the ring plate 12
An EGR valve body is formed to appropriately open and close the outlet of the EGR passage 9 to control the EGR flow rate. Here, a single screw hole 21 is provided in the ring plate 12, and a rod 23 is rotatably attached to the ring plate 12 via a pillow ball 24 using the screw hole 21 and a screw member (cap screw) 22. Have been. Rod 2
Numeral 3 penetrates the center housing 2 at an appropriate position, extends to the outside, and is advanced and retracted by an actuator (for example, a negative pressure diaphragm) not shown. This makes it possible to operate the ring plate 12 from outside, and the EG
Opening / closing control of the outlet of the R passage 9 becomes possible.

In the above configuration, a ring plate 12 as an EGR valve is provided inside the compressor section, and the ring plate 12 has an outlet hole 19 as a fixed slit.
Is opened and closed, so that the conventional EGR valve for the external piping is not required, and the number of throttles can be reduced by one, thereby reducing the passage resistance and performing the EGR at a sufficient flow rate. Thus, a compact turbocharger incorporating the EGR valve can be obtained. The elimination of the EGR valve also enables simplification and cost reduction. Due to the structure, the ring plate 12 alone is
In the case where the R passage cannot be completely closed, the EGR valve of the external piping may be left and used for full closing. Even in this case, since the EGR valve can only be fully opened and fully closed, an EGR valve having a low passage resistance can be used, thereby maintaining the above-described effect.

[Second Embodiment] Next, a second embodiment of the present invention will be described.
An embodiment will be described. The same components are denoted by the same reference numerals in the drawings, and description thereof will be omitted.

As shown in FIG. 4, in this embodiment, an opening / closing plate 31 as an EGR valve body is slidably inserted in the seal plate 7a in the radial direction. The seal plate 7a is fixed by press-fitting or the like to the ring-shaped groove 8a in which the step surface 14 is eliminated, and has a thickness greater than that of the seal plate 7 and an opening / closing plate at an intermediate portion in the thickness direction. A slit-like hole 32 for inserting the same 31 is formed. As shown in FIG. 5, the slit-shaped hole 32 is formed in a substantially rectangular shape having a predetermined width in the circumferential direction and long in the radial direction, has an inner peripheral end face 33 on the radial inner side, and has a radial outer side. The ends are open. And the impeller outlet 1 is connected to the seal plate 7a.
An outlet hole 19a opening to the opening 8 is formed through. Therefore, the opening / closing plate 31 reciprocates in the radial direction to appropriately open / close the outlet hole 19a.

Here, the outlet hole 19a is formed in a rectangular long hole shape that is long in the circumferential direction. The opening and closing plate 31 is
Having a width, length and thickness that fits the slit-shaped hole 32,
Its width is formed larger than the outlet hole 19a. The inner peripheral end face 33 of the slit-shaped hole 32 is located radially inward of the outlet hole 19a, whereby the outlet hole 19a is completely closed when the opening / closing plate 31 abuts against the inner peripheral end face 33.

As shown in FIG. 6, these open / close plates 3
The slits 1 and the slit-shaped holes 32 are arranged at four locations in the circumferential direction at 90 ° intervals. The movement of the open / close plate 31 is all performed simultaneously by the interlocking mechanism 34. The interlocking mechanism 34 includes a rod 35 integrally extending radially outward from the opening / closing plate 31, a right-angle crank 38 to which the rod 35 is connected to one arm 36, and which can rotate around a fixed shaft 37. A ring body 40 is engaged with the other arm 39 of the crank 38 and is supported by a fixed system such as the compressor housing 1 and the center housing 2 so as to be movable in the circumferential direction. An operation rod 41 is rotatably connected to one portion of the ring body 40, and the operation rod 41 is connected to an actuator 42 such as a negative pressure diaphragm.
As a result, the ring body 40 and the right-angle crank 38 are rotated, and the opening / closing plate 31 is reciprocated in the radial direction. The fixed shaft 37 is also supported by a fixed system such as the compressor housing 1 and the center housing 2.

In this manner, the outlet hole 19a of the seal plate 7a is opened and closed appropriately, and the same operation and effect as in the first embodiment are exhibited. In this embodiment, the opening / closing plate 31 is inserted into the slit-shaped hole 32 for engagement. However, any other method can be considered. For example, the key-shaped protrusion and the groove are engaged. You may make it slide. Other configurations are also possible for the interlocking mechanism, and the actuator 42 may be a fluid pressure cylinder, a servomotor, or the like. In particular, as shown in FIG.
a, the one provided on the wall portion on the rear side in the axial direction is divided in the radial direction, and the opening hole
It is also possible to increase or decrease the substantial opening area of a in multiple steps.

Various other embodiments of the present invention are conceivable. For example, the outlet of the EGR passage can have various shapes, sizes, and numbers of openings in addition to the above-described outlet holes. The outlet may be formed by a gap between the seal plate and the center housing. Further, the EGR valve body is provided with openings of various shapes, sizes, numbers, etc.
You may make it correspond with the exit part of a GR passage. Further, the EGR valve body may have any shape or structure other than the plate-like one as described above. Such a turbocharger is also applicable to gasoline engines and the like.

[0023]

According to the present invention, the EGR valve in the external pipe is eliminated to reduce the passage resistance and increase the EGR flow rate.
It realizes a compact turbocharger with a built-in GR valve, and at the same time, has an excellent effect of simplifying the configuration and reducing the cost.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing a main part of a first embodiment.

FIG. 2 is a front view showing a ring plate.

FIG. 3 is a front view showing an outlet hole and a hole portion when viewed from the right side of FIG. 1;

FIG. 4 is a longitudinal sectional side view showing a main part of a second embodiment.

FIG. 5 is a front view showing an outlet hole and an opening / closing plate when viewed from the right side of FIG. 4;

FIG. 6 is a front view showing an interlocking mechanism.

FIG. 7 is a vertical sectional side view showing a modified example of an outlet hole.

FIG. 8 is a configuration diagram showing a general turbocharged engine.

[Explanation of symbols]

 7, 7a Seal plate 9 EGR passage 12 Ring plate 18 Impeller outlet 19, 19a Exit hole 20 Hole 31 Opening / closing plate

Claims (3)

[Claims] An EGR passage is defined inside a compressor section, an outlet of the EGR passage is opened to an impeller outlet, and an EGR flow is controlled by opening and closing the outlet of the EGR passage. A turbocharger provided with the EGR valve element of (1). 2. The ring plate according to claim 2, wherein an outlet of said EGR passage comprises an outlet hole formed in a seal plate, and said EGR valve body is superimposed on said seal plate and slidable in a circumferential direction. 2. The turbocharger according to claim 1, comprising a ring plate having a hole communicating with the outlet hole. 3. The EGR passage according to claim 1, wherein an outlet portion of the EGR passage comprises an outlet hole formed in a seal plate, and the EGR valve body comprises an opening / closing plate which is engaged with the seal plate and is slidable in a radial direction. 1. The turbocharger according to 1.