JPH06323152A - Supercharger for engine - Google Patents

Abstract

PURPOSE:To improve emission by assist driving a turbocharger to increase a rotational speed of a compressor while supplying secondary air from the compressor to an exhaust side, in at least a low speed region at engine cold time. CONSTITUTION:In a supercharger formed by additionally providing an assist driving hydraulic turbine, turned by delivery oil from an engine-driven oil hydraulic pump 108, in a compressor rotary shaft of a turbocharger 24, the downstream part from a compressor 30 of a common intake pipe 14 and the upstream part from a turbine 32 of a common exhaust pipe 20 are connected to each other by a secondary air supply passage 113, to provide a supply switching valve 111 interposed on the halfway of the passage 113. At engine cold time, by an ECU 120, the supply switching valve 111 is opened, and also assist driving the assist driving hydraulic turbine by delivery oil by the oil hydraulic pump 108. Thus by forcing the compressor 30 driven, supercharge air is supplied to an exhaust side from the secondary air supply passage 113, and emission decrease at cold time can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supercharger for an engine equipped with a turbocharger.

[0002]

2. Description of the Related Art Generally, an engine equipped with a turbocharger tends to be inferior in starting acceleration performance to an engine having no turbocharger. This is because the engine speed at start-up is insufficient, so the amount of exhaust gas that can drive the compressor and turbine of the turbocharger with the torque that can obtain the desired acceleration cannot be obtained, and the turbocharger will not be used for supercharging. Because the compression ratio of the engine is set low by that much, the output torque is rather reduced.

Therefore, in the prior art, for example, Japanese Patent Laid-Open No. 3-2493.
As disclosed in Japanese Patent Publication No. 29, a hydraulic turbine is mounted on a shaft connecting a compressor wheel and a turbine wheel, and hydraulic oil discharged from the hydraulic pump under a predetermined condition such as start acceleration is directed to the hydraulic turbine to a nozzle. A supercharging device has been proposed in which the shaft is integrally driven with the hydraulic turbine by injecting through the auxiliary injection, thereby increasing the output of the turbocharger.

[0004]

In the above engine, since the heat capacity of the turbocharger is relatively large, the temperature rise of the exhaust gas purifying catalyst at the cold start of the engine is delayed accordingly. Therefore, as compared with other normal engines that do not have a turbocharger, the reduction in emission during cold start is more noticeable, and improvement thereof is a major issue.

In view of the above circumstances, the present invention makes it possible to effectively improve the emission of a turbocharged engine, particularly when the engine is cold-started, by using the turbocharger. The purpose is to provide a device.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an engine provided with auxiliary drive means for auxiliary driving a connecting shaft interconnecting a compressor provided in an intake passage and a turbine provided in an exhaust passage in a turbocharger. In the supercharger, a secondary air supply passage that communicates a portion of the intake passage on the downstream side of the compressor with a portion of the exhaust passage on the upstream side of the exhaust gas purification catalyst, and opens the secondary air supply passage. Opening / closing means for switching between a closed state and a closed state, a temperature state detecting means for detecting the temperature state of the engine, and a temperature state detected by the temperature state detecting means in a preset low temperature range and engine rotation. When the number is at least in a preset low speed range, the auxiliary drive means is operated and the opening / closing means is opened. It is obtained by a boost pressure control means for changing (claim 1).

More preferably, the secondary air supply passage is connected to a portion of the exhaust passage upstream of the turbine (claim 2).

Further, the connecting shaft is divided into a compressor side shaft and a turbine side shaft which are arranged coaxially with each other, and the compressor side shaft and the turbine side shaft are connected so as to rotate interlockingly with each other and relative rotation with respect to each other. The auxiliary drive means is configured so as to auxiliary drive the compressor side shaft, and the clutch means is disengaged in the operation region where the opening / closing means is switched to the open state. Or the auxiliary drive means is configured such that the auxiliary drive means operates with the power of the engine as a drive source, and the compressor in the intake passage. The bypass that bypasses the upstream passage and the passage that communicates with the downstream passage can be switched between By providing the bypass means, and configuring the supercharging control means so as to switch the intake bypass means to the communication state in an operating region where the opening / closing means is switched to the open state (claim 4), the following Excellent effect can be obtained.

[0009]

In the apparatus according to the first aspect of the present invention, the rotational speeds of the compressor and the turbine are increased by auxiliary driving the turbocharger at least in the low speed range when the engine is cold. The supercharging pressure is increased by the increase in the rotation speed of the compressor, and the high-pressure air discharged from the compressor is supplied as secondary air to the upstream side of the exhaust purification catalyst in the exhaust passage through the secondary air supply passage. The promotion of the exhaust pulsation due to the increase in the rotational speed of the turbine promotes the mixing of the secondary air and the exhaust gas.
As a result, the exhaust purification reaction in the exhaust purification catalyst is promoted, and the emission is improved accordingly.

Particularly, in the apparatus according to the second aspect, since the secondary air pressurized by the compressor is supplied to the upstream side of the turbine, the secondary air is more effective as the exhaust gas due to the rotation of the turbine. Be stirred.

Further, in the apparatus according to the third aspect, in the secondary air supply region, the compressor side shaft of the turbocharger is separated from the turbine having a large moment of inertia and the turbine side shaft, and only the compressor and the compressor side shaft are driven for auxiliary rotation. Therefore, as compared with the case where the compressor and the turbine are integrally driven in the auxiliary rotation, the compressor rotation speed and the supercharging pressure are further increased, and the supply amount of the secondary air is correspondingly increased. Further, since the exhaust gas energy also increases due to the increase of the supercharging pressure and the turbine rotation speed also increases as compared with the case where the auxiliary drive is not performed, the secondary air and the exhaust gas due to the exhaust pulsation resulting from this turbine rotation are The mixing effect is also promoted.

According to the fourth aspect of the present invention, in the secondary air supply region, the compressor in the intake passage is bypassed to open the upstream passage and the downstream passage,
Since the work of the compressor increases due to the intake air recirculation due to the opening, the load of the auxiliary drive means for driving the compressor and thus the load of the engine increases. As a result, the warm-up of the engine is promoted, and the exhaust gas purification reaction in the exhaust gas purification catalyst is further promoted.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS.

A common intake pipe 14 is connected to each cylinder of the engine 10 shown in FIG. 1 via an intake manifold 12. In the middle of the common intake pipe 14, a throttle valve 15, an intercooler 16, a turbocharger (actually, a turbocharger that also has a function as a supercharger that receives auxiliary drive as described later) 2
4, an air cleaner 18 and the like are provided.

In the common intake pipe 14, an upstream side portion and a downstream side portion of the turbocharger 24 are connected by a bypass passage 17 that bypasses the turbocharger 24, and an intake bypass is provided in the middle of the bypass passage 17. A valve 21 is provided. This intake bypass valve 21
Is constituted by an electromagnetic switching valve or the like, and is configured to be capable of receiving a signal from the outside and switching between a state where the bypass passage 17 is opened and a state where the bypass passage 17 is blocked.

Further, a common exhaust pipe 20 is connected to each of the cylinders via an exhaust manifold 19, and the turbocharger 24 and an exhaust gas purifying catalyst (three in this embodiment) are provided in the middle of the common exhaust pipe 20. The original catalyst) 22 and the like are provided.

The internal structure of the turbocharger 24 is shown in FIGS. The turbocharger 24 includes a compressor 26 and a turbine 28, similar to a normal turbocharger. The compressor 26 is housed in a compressor housing 30, and the turbine 28 is housed in a turbine housing 32. The compressor housing 30 is incorporated in the middle of the common intake pipe 14,
The turbine housing 32 is incorporated in the middle of the common exhaust pipe 20, and the housings 30 and 32 are connected to each other via a substantially cylindrical main body housing 34.

The compressor 26 is made of a relatively lightweight material such as aluminum and has a relatively thin wall, while the turbine 28 is made of a relatively heavy material such as an iron-based material to withstand the high heat of exhaust gas. It is formed thick. Therefore, the moment of inertia of the turbine 28 is significantly larger than the moment of inertia of the compressor 26.

A compressor side shaft 36 and a turbine side shaft 38 are housed in the center of the main body housing 34 in a coaxial state with the main body housing 34. And the compressor side shaft 36
The outer end (the right end in FIG. 2) of the compressor 2 is
The outer end of the turbine-side shaft 38 (the left end in FIG. 2) is fixed to the center of the turbine 28.

An inner end portion (left end portion in FIG. 2) of the compressor-side shaft 36 is a cylindrical portion 37 that opens toward the tip.
The inner end portion (right end portion in FIG. 2) of the turbine side shaft 38 is a small-diameter fitting portion 39 that is fitted into the cylindrical portion 37 so as to be relatively rotatable.

An outer cylinder 41 is fitted on the outer side of the compressor side shaft 36 in the radial direction so as to rotate integrally therewith.
A portion of the outer cylinder 41 from the turbine side (see FIG. 2).
A hydraulic turbine (auxiliary drive turbine) 43 is integrally formed in a part from the left side; a part in the main body housing 34 in the center in the left-right direction. In this embodiment, the hydraulic turbine 43 is formed in the shape of a Pelton wheel, and the working oil is sprayed from the predetermined direction on the outer peripheral portion of the hydraulic turbine 43 so that the hydraulic turbine 43 is driven to rotate integrally with the outer cylinder 41 and the compressor side shaft 36. It is configured.

A cylindrical bearing housing 40 is fitted inside the main body housing 34 and extends over substantially the entire axial direction thereof. And, in this bearing housing 40,
Both the outer cylinder 41 outside the compressor side shaft 36 and the turbine side shaft 38 are rotatably supported via bearings 42. An oil passage forming ring 45 is arranged beside each bearing 42.

A hydraulic clutch (clutch means) 44 as shown in FIG. 3 is provided between the compressor side shaft 36 and the turbine side shaft 38. This hydraulic clutch 4
4 is composed of an oil passage forming block 46, a sleeve 48, an outer clutch member 50, an inner clutch portion 52, a spring 58 and the like.

The oil passage forming block 46 is provided with an oil passage for a hydraulic clutch hydraulic oil, which will be described later, and has a tubular shape as a whole. A portion of the oil passage forming block 46 from the turbine is a large diameter portion 46a which is substantially in sliding contact with the inner peripheral surface of the bearing housing 40, and a portion from the compressor is a small diameter portion 46b having a smaller diameter than the large diameter portion 46a. The entire oil passage formation block 46 is externally fitted and fixed to the turbine side shaft 38. In addition, this oil passage formation block 46
A ring 55 is fixed at the boundary between the large diameter portion 46a and the small diameter portion 46b.

The outer clutch member 50 is the turbine side shaft 3
It has a tubular portion having an inner diameter larger than the outer diameter of 8, and is fixed to an intermediate portion of the turbine side shaft 38 while being sandwiched between the nut 51 and the oil passage forming block 46. The tubular portion is open toward the compressor-side shaft 36, and a peripheral inner peripheral surface of the opening end is a tapered inner peripheral surface whose diameter decreases toward the inner side (left side in FIG. 3) of the tubular portion. 53
It is said that.

On the other hand, the inner clutch portion 52 is formed integrally with the end portion of the tubular portion 37 of the compressor side shaft 36 and has a tubular shape. The outer peripheral surface of the inner clutch portion 52 is a tapered outer peripheral surface 54 that can be pressed against the tapered inner peripheral surface 53 of the outer clutch member 50 from the inside.

The sleeve 48 is the outer clutch member 5 described above.
0 is in sliding contact with the outer peripheral surface from the outside, and the inner clutch portion 52 is provided at the compressor side end portion (the right end portion in FIG. 3).
A ring 56 holding the compressor from the compressor side is fixed. Further, a collar portion 49 projecting from the proper position of the sleeve 48 toward the inner oil passage forming block 46 is formed, and a hydraulic chamber 59 is formed between the collar portion 49 and the ring 55. There is.

The collar 49 and the outer clutch member 5
A spring (pressing means) 58 is press-fitted between 0 and 0. The spring 58 urges the sleeve 48 and the ring 56 toward the turbine by its elastic force.
By this elastic force, the compressor side shaft 36 is pressed toward the turbine side so as to be held by the ring 56 from the compressor side, and this pressing normally causes the outer tapered surface 54 of the inner clutch portion 52 to move to the outer clutch member. The inner tapered surface 53 of 50 is press-contacted from the inside, and the compressor-side shaft 36 and the turbine-side shaft 38 are coaxially and non-rotatably connected by the frictional force due to the pressure contact of the tapered surfaces 53 and 54. There is.

Next, the oil passage of the hydraulic oil formed in the turbocharger 24 will be described. In this embodiment, the lubricating oil of the bearing 42 is commonly used as the working oil.

A hydraulic oil supply port 62 is formed at an appropriate position on the side wall of the main body housing 34, and the hydraulic oil supply port 6 is formed.
2 is communicated with the bearing housing 40 via a hydraulic oil supply passage 64. A groove 65 communicating with the hydraulic oil supply passage 64 is formed on the side wall of the bearing housing 40 over the entire circumference, and a plurality of hydraulic oil injection ports 63 that communicate the groove 65 with the inside of the bearing housing 40 are bored. ing. The position of each hydraulic oil injection port 63 is formed at a position where the hydraulic oil injected from the injection port 63 is sprayed onto the outer peripheral portion of the hydraulic turbine 43, whereby the hydraulic turbine 43 is rotationally driven.

On the side wall of the main body housing 34, a hydraulic oil supply port 66 is provided at a position different from the hydraulic oil supply port 62, and the hydraulic oil supply port 66 is opened at a position different from the groove 65 in the bearing housing 40. ing. A groove 69 is formed over the entire circumference in a portion of the bearing housing 40 facing the opening, and
A plurality of hydraulic oil supply ports 67 are formed to connect the groove 69 and the outer peripheral surface of the large diameter portion 46a of the oil passage forming block 46 in the bearing housing 40.

A hydraulic oil passage 70 is formed in the center of the turbine side shaft 38 along the central axis thereof. The turbine-side shaft 38 and the large-diameter portion 46a of the oil passage forming block 46 are formed with working oil passages 71 and 68 that communicate the working oil supply port 67 and the working oil passage 70 in the radial direction. Further, a portion of the turbine shaft 38 closer to the compressor than the working oil passage 71 and a small diameter portion 46b of the oil passage forming block 46 are provided with working oil for communicating the working oil passage 70 and the hydraulic chamber 59 in the radial direction. The paths 73, 72 are formed.

The hydraulic oil is supplied from the hydraulic oil passages 73, 72 into the hydraulic chamber 59, and the hydraulic pressure causes the sleeve 48 and the ring 56 to move to the spring 58.
Is pushed to the compressor side against the elastic force of the compressor (see the chain double-dashed line in FIG. 3), and the pressure contact between the tapered surfaces 53 and 54 is released, so that the compressor side shaft 36 and the turbine side shaft 38 can rotate relative to each other. It is designed to be separated into.

The main body housing 34 is formed with working oil recovery paths 81, 82 which communicate with the inside of the bearing housing 40, and these are joined to the working oil discharge port 84.

In the main body housing 34, the lubricating oil supply port 8 is provided at a position different from the hydraulic oil supply port 62.
6 is formed. The lubricating oil supply port 86 is provided with lubricating oil supply passages 88, 9 formed in the main body housing 34.
4 to the outer peripheral surface of the bearing housing 40.

Grooves 89 and 96 are formed on the outer peripheral surface of the bearing housing 40 at positions connecting to the lubricating oil supply passages 88 and 94, and the bearing housing 40 and the oil passage forming ring 45 are formed. The lubricating oil passages 90 and 98 communicating with the grooves 89 and 96 are formed therein. In each oil passage forming ring 45, each lubricating oil passage 90, 9
8 are formed to communicate with the oil jets 9 and 8. The direction of each of the oil jets 92 and 99 is such that the lubricating oil injected from these oil jets 92 and 99 corresponds to each bearing 4
It is set to be supplied to two sliding parts.

In the main body housing 34, a lubricating oil recovery passage 80 communicating with the openings at both ends of the bearing housing 40,
83 is formed, and these merge with the hydraulic oil discharge port 84.

In FIG. 3, reference numeral 78 is a passage securing plug, and 100 is a water jacket formed in the main body housing 34.

As shown in FIG. 1, a hydraulic pump 108 is connected to a crankshaft 102 of the engine 10 via a drive transmission mechanism 104 and a pump clutch 106. The hydraulic pump 108 is connected to both the hydraulic oil supply ports 62 and 66 via a pressure regulating valve 110.

The pump clutch 106 is switched between an on state in which the drive transmission mechanism 104 and the hydraulic pump 108 are connected and an off state in which they are separated from each other. In the on state, the drive force of the crankshaft 102 is transmitted to the drive transmission mechanism 104.
The hydraulic pump 108 is configured to operate by being transmitted to the hydraulic pump 108 via.
The operation of the hydraulic pump 108 causes the engine 1 to operate.
The lubricating oil in 0 is hydraulically sent to the hydraulic oil supply ports 62 and 66 via the pressure regulating valve 110.

Further, the portion of the common intake pipe 14 between the compressor 26 and the air cleaner 18 and the portion of the common exhaust pipe 20 upstream of the turbine 28 are secondary as shown in FIG. Air supply passage 1
It is communicated via 13. This secondary air supply passage 1
A supply switching valve 111 for opening and closing the passage and a reed valve 112 for preventing backflow are provided in the middle of 13. The supply switching valve 111 is composed of an electromagnetic valve and is adapted to be switched between a state in which the secondary air supply passage 113 is opened and a state in which the secondary air supply passage 113 is blocked by the input of a signal from the outside.

As shown in FIG. 1, in this engine, a turbine rotation speed sensor 114 for detecting the rotation speed Nt of the turbine 28 per unit time, and an engine temperature for detecting the temperature state of the engine by detecting the engine water temperature and the like. A sensor 115, a throttle sensor 116 for detecting the throttle opening θ of the throttle valve 15, an engine speed sensor 117 for detecting the engine speed Ne, an engine intake pipe boost sensor 118 for detecting the intake pipe internal pressure, and the like are provided. Sensors are connected to an ECU (control unit; drive control means) 120. ECU1
Reference numeral 20 is configured to perform on / off control of the pump clutch 106, open / close control of the intake bypass valve 21 and the supply switching valve 111, and the like, based on the detection signals of the respective sensors.

Next, the control operation performed by the ECU 120 and the operation of the entire apparatus will be described with reference to the flowchart of FIG.

First, the ECU 120 receives a detection signal from the engine temperature sensor 115 and compares the detected temperature Tw with a preset temperature To (step S1).

When the detected temperature Tw is lower than the set temperature To (when the engine is cold; YES in step S1), the pump clutch 106 is turned on and the supply switching valve 111 is turned on. Open (step S2).

When the pump clutch 106 is turned on, the hydraulic pump 108 operates, and the lubricating oil in the engine 10 is regulated to a constant pressure by the pressure regulating valve 110 and then supplied to the hydraulic fluid supply port 62 of the turbocharger 24. This hydraulic oil is injected from the hydraulic oil injection port 63 into the hydraulic turbine 43 of the outer cylinder 41 through the groove 65, whereby the outer cylinder 41 is
Together with the compressor shaft 36 and further the compressor 26
Is driven by auxiliary rotation and is accelerated. At the same time, the hydraulic oil is supplied from the hydraulic oil supply port 66 to the groove 69 and the hydraulic oil supply port 6.
7. The hydraulic oil passages 68, 71, 70, 73, 72 are sequentially introduced into the hydraulic chamber 59, and the sleeve 48 is pushed back to the compressor side (right side in FIG. 3) against the elastic force of the spring 58. As a result, the force of the spring 58 pushing the inner clutch portion 52 into the inner side of the outer clutch member 50 by the elastic force through the ring 56 is released, and accordingly, the outer tapered surface of the inner clutch portion 52 is released. 5
The pressure contact between 3 and the inner tapered surface 54 of the outer clutch member 50 is also released. Therefore, the compressor-side shaft 36 and the turbine-side shaft 38, which have been connected to each other by the frictional force resulting from this pressure contact force, are separated from each other so that they can rotate relative to each other.

In other words, the supply of the hydraulic oil causes the compressor-side shaft 36 and the turbine-side shaft 38 to be separated from each other almost simultaneously with the rotational driving of the hydraulic turbine 43. As a result, only the compressor 26 having a small moment of inertia and the compressor-side shaft 36 are driven to perform auxiliary rotation. The rotation speed is further increased, and the boost pressure also rises quickly. Further, as the supercharging pressure increases, the exhaust gas energy also increases, so that the rotation speed of the turbine 28 also increases as compared with the case where there is no auxiliary drive.

On the other hand, when the supply switching valve 111 is opened, the high pressure air discharged from the compressor 26 bypasses the engine 10 and directly flows to the common exhaust pipe 19 (more specifically, the upstream side of the turbine 28). It is supplied as secondary air. Then, this secondary air is mixed with the exhaust gas by the rotation of the turbine 28, and then the exhaust gas purifying catalyst 2
2 is sent to the exhaust gas purifying catalyst 22.
Exhaust gas purification reaction (for example, HC or CO oxidation reaction)
Is promoted.

Until the time t _EM from the start of such secondary air supply reaches the preset time to (NO in step S3), the ECU 120 causes the engine intake pressure, the throttle opening θ, and Engine speed Ne,
The predicted value Nc of the compressor rotation speed is calculated based on the map stored in advance (step S4). When the turbine speed Nt reaches the predicted value Nc (YES in step S5) or when the time t _EM reaches the set time to (YES in step S3), the pump clutch 106 is turned off. While switching to
The supply switching valve 111 is closed (step S6).

By turning off the pump clutch 106,
Since the hydraulic oil is stopped from being supplied to the hydraulic chamber 59 by the hydraulic pump 108, the elastic force of the spring 58 causes the tapered outer peripheral surface 54 of the inner clutch portion 52 to return to the tapered inner peripheral surface 53 of the outer clutch member 50. The compressor side shaft 36 and the turbine side shaft 3 are pressed against each other and the frictional force generated by the pressure contact
8 and 8 are coaxially connected to each other such that they cannot rotate relative to each other. Therefore, the compressor 26 rotates integrally with the turbine 28, and like the normal turbocharger 24, the turbine 2
8 by the exhaust gas energy recovered by the compressor 2
6 will be driven to rotate.

On the other hand, when the detected temperature Tw is equal to or higher than the set temperature To (NO in step S1), the on / off state of the pump clutch 106 is confirmed at that time (step S7). When the pump clutch 106 is off (NO in step S7), this is maintained, and when the pump clutch 106 is on (YE in step S7).
S), the clutch-on state is maintained only when the engine speed Ne is less than the constant value No and the engine load Pe exceeds the constant value Po (that is, the high load low rotation state) (YES in step S8), and otherwise. If (step S8
If NO), the above steps S4 and S5 are executed.

According to such a device, the following effects can be obtained.

(A) When the engine is cold, the supply switching valve 111 is opened to supply the secondary air discharged from the compressor 26 to the exhaust side. Therefore, by mixing the secondary air with the exhaust gas. The exhaust gas purification reaction in the exhaust gas purification catalyst 22 can be promoted. Moreover, in this secondary air supply area, the turbocharger 24
Since the rotational speeds of the compressor 26 and the turbine 28 are increased by auxiliary driving of the compressor 26, the supercharging pressure is increased due to the increase in the rotational speed of the compressor 26 to increase the secondary air supply amount to the exhaust side, and By increasing the exhaust pulsation caused by the rotation of the exhaust gas, the mixing of the secondary air with the exhaust gas can be further promoted, and the exhaust gas purification reaction can be further promoted by that amount, and the emission can be improved.

(B) Since the secondary air is supplied to the upstream side of the turbine 28, the rotation of the turbine 28 can further promote the agitation of the secondary air and the exhaust gas.

(C) In the secondary air supply region, the compressor-side shaft 36 and the turbine-side shaft 38 are rotatably separated from each other, and only the compressor 26 is driven independently.
Compared with a case where both shafts 36 and 38 are connected to integrally drive the compressor 26 and the turbine 28 having a large moment of inertia, the compressor rotation speed can be further increased with the same drive load. Therefore, the supercharging pressure can be further increased by that amount, and more secondary air can be supplied to the exhaust side to further promote exhaust gas purification.

In addition to these effects, if the intake bypass valve 21 is opened in the secondary air supply region (that is, the air discharged from the compressor 26 is recirculated to the upstream side of the compressor), this intake air recirculation Increase the work of the compressor 26,
It is possible to increase the load of the hydraulic pump 108 that drives the motor 6, that is, the load of the engine. Therefore, the increase in the load can accelerate the warming up of the engine 10 at the time of cold starting, and thus the temperature rise of the exhaust gas purifying catalyst 22.
The effect of further promoting exhaust gas purification at the time of this cold start can be obtained.

FIG. 5 shows changes with time in each of the introductions of the apparatus of the embodiment and the conventional apparatus. A solid line 200 in the drawing shows a vehicle speed, and solid lines 201, 202,
Reference numeral 203 denotes the exhaust gas temperature, the HC concentration in the exhaust gas before passing through the exhaust gas purifying catalyst, and the HC concentration in the exhaust gas after passing through the exhaust gas purifying catalyst, respectively, in the conventional apparatus. , 213 respectively show the exhaust gas temperature, the HC concentration in the exhaust gas before passing through the exhaust gas purifying catalyst, and the HC concentration in the exhaust gas after passing through the exhaust gas purifying catalyst in the above-described apparatus. As is clear from this figure, according to the apparatus of the above-mentioned embodiment, the vehicle speed, the exhaust gas temperature, and the HC concentration in the exhaust gas before purification are substantially equal to those in the conventional case, respectively, and the HC concentration in the exhaust gas after purification, particularly the engine. It is possible to significantly reduce the concentration at the cold start as compared with the conventional device.

The present invention is not limited to such an embodiment, and the following modes can be adopted as an example.

(1) In the above embodiment, the auxiliary drive of the turbocharger 24 and the secondary air supply are performed unconditionally when the engine is cold. However, in the present invention, at least in the low speed region when the engine is cold. By performing the auxiliary drive and the secondary air supply, it is possible to obtain the effect of improving the emission at the cold start of the engine.

(2) In the present invention, the connection point of the secondary air supply passage 113 to the exhaust side (that is, the secondary air supply point) is not particularly limited. However, in order to effectively use the rotation of the turbine 28 by mixing the secondary air and the exhaust gas, it is important to set the connection point on the upstream side of the turbine 28.

(3) In the above embodiment, the compressor side shaft 3
Although the turbocharger 24 in which the shaft 6 and the turbine side shaft 38 are separated is shown, the shaft is auxiliary driven in the secondary air supply region even in a device including a normal turbocharger in which both shafts always rotate integrally. Therefore, it is possible to improve the emission.

[0062]

As described above, according to the present invention, the following effects can be obtained.

In the apparatus according to the first aspect, the secondary air discharged from the compressor is supplied to the exhaust side in at least the low rotation region when the engine is cold, and
In this secondary air supply region, the turbocharger is auxiliary-driven to increase the rotational speeds of the compressor and the turbine. The supply amount can be increased and the mixing of the secondary air with the exhaust gas can be promoted, and the exhaust gas purification reaction can be further promoted by that amount. Therefore, there is an effect that the emission can be significantly improved by effectively using the turbocharger.

Particularly, in the apparatus according to the second aspect, since the secondary air is supplied to the upstream side of the turbine, rotation of the turbine further enhances the effect of stirring the secondary air and the exhaust gas, and the exhaust gas is exhausted. There is an effect that the gas purification reaction can be further promoted.

Further, in the apparatus according to the third aspect, the compressor is separated from the turbine at the time of the predetermined deceleration and only the compressor is auxiliary driven. Therefore, when the compressor and the turbine are connected to each other at the predetermined deceleration, both of them are auxiliary driven. In comparison with the above, it is possible to maintain the compressor rotation speed at the predetermined deceleration at a higher rotation speed. Therefore, there is an effect that the secondary air supply amount by the rotation of the compressor can be further increased and the emission can be further improved.

Further, in the apparatus according to the fourth aspect, the intake bypass means is switched to the open state in the secondary air supply region,
Since the air on the downstream side of the compressor is recirculated to the upstream side of the compressor, this intake air recirculation can increase the load of the auxiliary drive means of the compressor and thus the engine load. Therefore, there is an effect that warming up of the engine at the time of cold starting and thus temperature rise of the exhaust gas purifying catalyst can be accelerated by the amount of this increase in load, and the exhaust gas purifying performance at this cold starting can be further enhanced.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an engine according to a first embodiment of the present invention.

FIG. 2 is a sectional front view of a turbocharger provided in the engine.

FIG. 3 is a partially enlarged view of FIG.

FIG. 4 is a flowchart showing a control operation of an ECU provided in the engine.

FIG. 5 is a graph showing a difference in characteristics between the engine and a conventional engine.

[Explanation of symbols]

 10 engine 14 common intake pipe 17 bypass passage (constituting intake bypass means) 20 common exhaust pipe 21 intake bypass valve (constituting intake bypass means) 24 turbocharger 26 compressor 28 turbine 36 compressor side shaft 38 turbine side shaft 43 hydraulic turbine ( Auxiliary drive means) 44 Hydraulic clutch (clutch means) 62, 66 Hydraulic oil supply port 102 Crank shaft (engine output shaft) 108 Hydraulic pump (auxiliary drive means) 111 Supply switching valve (opening / closing means) 113 Secondary air supply passage 115 Engine Temperature sensor (temperature state detecting means) 120 ECU (supercharging control means)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display area F02B 39/12 9332-3G

Claims (4)

[Claims] 1. A supercharger for an engine, comprising: an auxiliary drive means for auxiliary driving of a connecting shaft interconnecting a compressor provided in an intake passage and a turbine provided in an exhaust passage in a turbocharger. In the secondary air supply passage communicating a portion downstream of the compressor with a portion upstream of the exhaust gas purifying catalyst in the exhaust passage, and a state of opening and blocking the secondary air supply passage. Switching means for switching, temperature state detecting means for detecting the temperature state of the engine, low temperature where the temperature state detected by the temperature state detecting means is in a preset low temperature range, and engine speed is at least a preset low speed And a supercharging control means for activating the auxiliary driving means and switching the opening / closing means to the open state when the vehicle is in the range. The supercharging device for the engine, which is characterized by 2. The supercharger for an engine according to claim 1, wherein the secondary air supply passage is connected to a portion of the exhaust passage on an upstream side of the turbine. 3. The engine supercharger according to claim 1, wherein the connecting shaft is divided into a compressor side shaft and a turbine side shaft which are arranged coaxially with each other, and the compressor side shaft and the turbine side shaft are separated from each other. The auxiliary drive means is configured to auxiliaryly drive the compressor side shaft, and the opening / closing means is provided with clutch means for switching between a connected state in which they are linked to rotate with each other and a disengaged state in which they are separated so as to rotate relative to each other. A supercharging device for an engine, characterized in that the supercharging control means is configured to switch the clutch means to a disengaged state in an operating region where the engine is switched to an open state. 4. The engine supercharger according to claim 1 or 2, wherein the auxiliary drive means is configured so that the auxiliary drive means operates by using the power of the engine as a drive source, and the compressor in the intake passage. And an intake bypass means for switching between a state in which the upstream side passage and the downstream side passage are communicated with each other and a state in which the upstream side passage and the downstream side passage are shielded,
A supercharging device for an engine, characterized in that the supercharging control means is configured to switch the intake bypass means to a communication state in an operating region where the opening / closing means is switched to an open state.