(1) Field of the Invention
The present invention relates to ventilation system and method for a supercharge engine having a turbocharger and particularly relates to a PCV system (a positive crankcase ventilation system) constituting a part of a blowby gas processing system.
(2) Description of Related Art
A Japanese Patent Application First Publication (tokkai) No. 2007-016664 published on Jan. 25, 2007 exemplifies a first previously proposed PCV system in a natural aspiration type engine or non-supercharge type engine includes: a blowby gas reduction passage which communicates between a downstream side position of an intake air passage (intake manifold) with respect to a throttle valve and a crank chamber (or a crankcase) of the engine; a fresh air introduction passage which communicates between an upstream side of the intake manifold with respect to the throttle valve and the above-described crankcase (crank chamber); and a PCV valve installed on the above-described blowby gas reduction passage.
In the first previously proposed engine ventilation system, at a time of a high load of the engine, when a negative pressure occurs within an inside of the engine due to an action of the PCV valve, fresh air is introduced within the crank case (crank chamber) via the fresh air introduction passage and, at the same time, blowby gas is mixed with fresh air within the crank case. Then, the mixed air is introduced at position of intake air passage located at the downstream side with respect to the throttle valve via the PCV valve. In this way, the crankcase is ventilated so that a deterioration of engine oil within the crank case is suppressed.
On the other hand, at a time of a high load of the engine, the negative pressure within the intake manifold becomes reduced (approaches to the positive pressure) and the quantity of blowby gas exhausted via the PCV valve becomes less than the quantity of blowby gas generated from the engine itself. Consequently, blowby gas within the crankcase is also exhausted from the fresh air introduction passage so that fresh air is not introduced into the crankcase. Thus, engine oil within the crankcase is deteriorated due to the blowby gas.
The above-described structure is basically the same as in a case of a turbo charger equipped (supercharge) engine. Specifically, in the turbo charged engine, as compared with the natural inspiration type engine or non-supercharger engine, the pressure in the intake manifold becomes high due to an influence of the supercharge pressure. Hence, a driving region in which fresh air is not introduced into the crankcase become increased. As a consequence, engine oil within the crank case becomes easy to be deteriorated due to the presence of blowby gas.
To avoid this inconvenience, the inventors have proposed a second previously proposed engine ventilation system, as disclosed in a Japanese Patent Application First Publication No. 2010-112178 published on May 20, 2010, in which an orifice for a fresh air introduction is disposed on a PCV, in the supercharge (type) engine, and fresh air is introduced within the crankcase via the PCV valve in a case where the boost pressure which is the pressure of the intake air passage indicates the positive pressure so that deterioration of engine oil within the crankcase is suppressed.
However, although, in a technique disclosed in the second previously proposed engine ventilation system, in a case where the boost pressure indicates a positive pressure, a ventilation efficiency of the crankcase is improved by introducing fresh air within the crankcase via the PCV valve from a position of the intake air passage which is located at the downstream side with respect to the throttle valve, a flow quantity of fresh air introduced into the crank chamber (crankcase) is not positively controlled and there is still a room of improvement.
It is, hence, an object of the present invention to provide ventilation system and method for the engine, especially, for the supercharge engine in which quantity of fresh air is appropriate for a present engine driving state in accordance with a driving state of the engine when the boost pressure of the intake air passage indicating the positive pressure is introduced within the crankcase.
According to one aspect of the present invention, there is provided with a ventilation system for a supercharge engine, comprising: a blowby gas reduction passage provided for communicating position of an intake air passage of the engine which is located at a downstream side with respect to a throttle valve with a crank chamber of the engine; a fresh air introduction passage provided for communicating position of the intake air passage which is located at an upstream side with respect to the throttle valve and the crank chamber; a PCV valve provided in the blowby gas reduction passage for controlling a flow quantity of blowby gas directed toward the intake air passage side in a case where a boost pressure at position of intake air passage located at downstream side with respect to the throttle valve indicates negative; and a fresh air flow quantity control section configured to operatively introduce fresh air into the crank chamber from position of intake air passage which is located at the downstream side with respect to the throttle valve in a case where the boost pressure at position of the intake air passage which is located at the downstream side with respect to the throttle valve is positive, wherein the fresh air flow quantity control section is configured to introduce fresh air into the crank chamber, in a middle load driving region in which the boost pressure at position of the intake air passage which is located at the downstream side with respect to the throttle valve is positive and the boost pressure is lower than a set pressure, and, in a high load driving region in which the boost pressure at part of the intake air passage which is located at the downstream side with respect to the throttle valve is equal to or higher than the set pressure, is configured to stop an introduction of fresh air from position of the intake air passage which is located at a downstream side with respect to the throttle valve or is configured to make a flow quantity of introduced fresh air at least smaller than a maximum flow quantity in the middle load driving region.
According to another aspect of the present invention, there is provided with ventilation method for a supercharge engine, comprising: providing a blowby gas reduction passage for communicating position of an intake air passage of the engine which is located at a downstream side with respect to a throttle valve with a crank chamber of the engine; providing a fresh air introduction passage provided for communicating position of the intake air passage which is located at an upstream side with respect to the throttle valve and the crank chamber; providing a PCV valve in the blowby gas reduction passage for controlling a flow quantity of blowby gas directed toward the intake air passage side in a case where a boost pressure at position of intake air passage located at downstream side with respect to the throttle valve indicates negative; and providing fresh air flow quantity control means for operatively introducing fresh air into the crank chamber from position of intake air passage which is located at the downstream side with respect to the throttle valve in a case where the boost pressure at position of the intake air passage which is located at the downstream side with respect to the throttle valve is positive, wherein fresh air is introduced into the crank chamber through fresh air flow quantity control means, in a middle load driving region in which the boost pressure at position of the intake air passage which is located at the downstream side with respect to the throttle valve is positive and the boost pressure is lower than a set pressure, and, in a high load driving region in which the boost pressure at part of the intake air passage which is located at the downstream side with respect to the throttle valve is equal to or higher than the set pressure, an introduction of fresh air from position of the intake air passage which is located at a downstream side with respect to the throttle valve is stopped or a flow quantity of introduced fresh air is at least made smaller than a maximum flow quantity in the middle load driving region.
The present invention described above is based on the knowledge such that, if fresh air is introduced into the crank chamber from position of the intake air passage which is located at the downstream side with respect to the throttle valve, the quantity of fresh air supplied to the engine is accordingly decreased. That is to say, in the middle load driving region, fresh air is introduced into the crank chamber from position of intake air passage which is located at the downstream side with respect to the throttle valve so that the crank chamber is positively ventilated. On the other hand, in the high load driving region requiring a high output of the engine, the introduction of fresh air into the crank chamber from position of the intake air passage which is located at the downstream side with respect to the throttle valve is stopped or a flow quantity of fresh air is made smaller than at least maximum flow quantity in the middle load driving region, in order to suppress the decrease in the fresh air quantity supplied to the engine.
According to the present invention described in the claims, in the middle load driving region of the engine, with importance placed on the ventilation of the crank chamber, relatively large quantity of fresh air is introduced into the crank chamber and, on the other hand, in the high load driving region, with importance placed on the engine output, the large quantity of fresh air is supplied to the engine so that, while the deterioration of engine oil within the crank chamber is suppressed, the output reduction of the engine in the high load driving region can be suppressed.
Reference will, hereinafter, be made to the drawings in order to facilitate a better understanding of the present invention.
In
Then, as is well known, intake air is passed through air cleaner 3 and airflow meter 4 and compressed (supercharged) by means of compression impeller 5b of turbo charger 5 driven by exhaust gas of engine 1. Thereafter, the compressed intake air is cooled by means of a subsequent stage of intercooler 6 and a flow quantity thereof is adjusted by means of throttle valve 7. Then, the flow quantity adjusted intake air is introduced into a combustion chamber of engine 1. It should be noted that part of exhaust gas from engine 1 is circulated into intake air system 2 via an EGR cooler 9.
Then, a blowby gas reduction passage 10 which communicates between position of intake air system 2 located at a downstream side with respect to throttle valve 7 and crankcase (or crank chamber) 1a of engine 1 is disposed and a fresh air introduction passage 11 which communicates between position of intake air system 2 located at an upstream side with respect to throttle valve 7, namely, the position of intake air system 2 which is located at the upstream side with respect to compressor impeller 5b of turbo charger 5 and crank chamber 1a of engine 1 is disposed.
PCV valve 12 and oilmist separator (OMS) 13 are serially interposed for PCV valve 12 to be in a throttle valve side 7 in blowby gas reduction passage 10. In addition, another oilmist separator (OMS) 14 is intervened for fresh air introduction passage 11. Either of oilmist separators 13, 14 is disposed independently of engine 1 and both of separators 13, 14 are installed so as to be connected with engine via hoses and so forth and both of oilmist separators 13, 14 are integrally installed together with a rocker cover (a cylinder head cover) of engine 1.
Furthermore, PCV valve 12 is provided with: a blowby gas flow quantity control orifice 15 which performs a flow quantity control function that PCV valve 12 naturally has, namely, a function to perform a control over a flow quantity of blowby gas directed toward intake air system 2 side; and a fresh air flow quantity control orifice 16 to control a flow quantity of fresh air directed toward crank chamber is as will be described later as fresh air flow quantity control means. In other words, while blowby gas flow quantity control orifice 15 functions as a variable orifice for a blowby gas flow quantity control, fresh air flow quantity orifice 15 functions as the variable orifice for the fresh air flow quantity control. In addition, fresh air flow quantity control orifice 16 is serially disposed at oilmist separator 13 side of the blowby gas flow quantity control orifice 15.
A flange section 23 is formed on an intermediate section of valve body 22 in the axial center direction of valve body 22. A first compression coil spring 26 is intervened between flange section 23 and cover 19. A second compression coil spring 27 is intervened between flange section 23 and a bottom wall of valve body main frame 18. Both tips of respective compressive coil springs 26, 27 are largely separated from each other than a thickness of flange section 23. When flange section 23 is seated on one of both compressive coil springs 26, 27, a gap G is formed between flange section 23 and the other of both coil springs 26, 27. In this way, a, so-called, play is provided on valve body 22 and an elastic force of only one of both compressive coil springs 26, 27 is acted upon valve body 22. Valve body 22 is so arranged as to be in a stable operation.
In addition, a first throat section 19a having a step section is formed on an opening section of cover 19 facing against valve body main frame 18. Position of valve body 22 which is located toward first port 22 against flange section 23 is formed as a tipped blowby gas metering section 24 having the diameter which becomes larger toward flange section 23. Then, when the boost pressure of intake air system 2 indicates negative, valve body 16 expanded according to the negative pressure of the boost pressure at intake air system 2 is slidably displaced against valve body 17. Valve body 22 comes to a stand-still at a balanced position between the boost pressure and first compressive coil spring 26. In other words, first throat section 19a and blowby gas metering section 24 are relatively displaced in accordance with a magnitude of the negative pressure so that an opening angle between first throat section 19a and blowby gas metering section 24 are relatively moved in accordance with a magnitude of the negative pressure so that the opening angle formed therebetween, namely, the flow quantity of blowby gas flowing into PCV valve 12 is variably controlled in a continuous manner.
In other words, a gap formed between first throat section 19a and blowby gas metering section 24 functions as blowby gas flow quantity control orifice 15.
On the other hand, a second port 21 formed on valve body main frame 18 is formed in a taper shape whose diameter becomes larger as it approaches to oilmist separator 13. Position of valve body 22 which is nearer to second port 21 than flange section 23 is formed as fresh air metering section 25 of a substantially stepped column shape and whose diameter becomes larger as it becomes larger in a stepwise manner.
Fresh air metering section 25 includes: a large diameter section 25a formed on a base section of fresh air metering section 25 and having a larger diameter than a second throat section 18a which is a minimum diameter section of second port 21; a middle diameter section 25b having a smaller diameter than second throat section 25b; and a taper section 25d formed between middle diameter section 25b and smaller diameter section 25c and whose diameter becomes gradually small toward small diameter section 25c.
Then, if the boost pressure at intake air system 2 indicates positive pressure, valve body 16 pressed by means of the positive pressure is slidably displaced and comes to the stand-still. Thus, the valve body becomes stand-still at the balanced position balanced between the boost pressure and the elastic force of second compressive coil spring 27. That is to say, a relative movement of second throat section 18a and fresh air metering section 25 occurs so that the opening angle formed between both elements and the flow quantity of fresh air flowing into PCV valve 12 is variably controlled in a continuous manner. In other words, the gap formed between second throat section 18a and fresh air metering section 25 functions as fresh air flow quantity control orifice 16.
Then, in blowby gas reduction passage 10 shown in
When, in the ventilation system so constructed as described above, the magnitude of the negative pressure with the boost pressure negative is large as shown in
Since, in this case, the blowby gas flow quantity denoted by sign B exhausted toward intake air system 2 via blowby gas reduction passage 10 is larger than the blowby gas development quantity denoted by sign A in
In addition, the load of engine becomes large from the above-described state and the boost pressure gradually approaches to the positive pressure. At this time, valve body 22 of PCV valve 12 in
Furthermore, in a positive pressure immediate prior state in which the boost pressure approaches to the positive pressure unlimitedly, the blowby gas flow quantity of sign B exhausted toward intake air system 2 via oilmist separator 13 and PCV valve 12 of blowby gas reduction passage 10 becomes less than blowby gas development quantity denoted by sign A. Then, the blowby gas is soon exhausted even from fresh air introduction passage 11 as shown in
When the load of engine 1 becomes furthermore large, the boost pressure in
Thus, the gas flow quantity in blowby gas reduction passage 10 denoted by sign B is turned to minus (−) at a middle load driving region A2 in which the boost pressure in
Furthermore, when the flow quantity of fresh air at blowby gas reduction passage 10 denoted by sign B in
Then, when the boost pressure has reached to predetermined set pressure P1, stepwise section 25e of fresh air metering section 25 is seated on the bottom wall of valve body 17, as shown in
Hence, in the first embodiment described above, is importance is placed on the ventilation of crank chamber 1a in middle load driving region A2 in
In addition, in the first embodiment, the introduction of fresh air into crank chamber 1a through blowby gas reduction passage 10 is stopped in high load driving region A3. However, the flow quantity of fresh air introduced into crank chamber 1a at high load driving region A3 is always not needed to be substantial zero or to be extremely small. If the flow quantity of fresh air introduced into crank chamber is in high load driving region A3 is set to be smaller than maximum flow quantity Q in the case of middle load driving region A2, at least the output reduction of engine 1 can be suppressed. It should be noted that, in a case where importance is placed on the engine output in high load driving region A3, it goes without saying that it is desirable to be set to the boost pressure-flow quantity characteristic shown in
In the second embodiment, in place of PCV valve 12 used in the first embodiment, PCV valve 28 is adopted which controls only the exhaust quantity of blowby gas from crank chamber is to intake air system 2 side and fresh air flow quantity control valve 29 is juxtaposed with PCV valve 28 which controls the introduction quantity of fresh air from intake air system 2 to crank chamber 1a. That is to say, blowby gas reduction passage 10 is branched or joined from or into position of intake air system 2 which is located at the downstream side with respect to throttle valve 7 in the same way as the first embodiment. However, a bypass passage 30 is provided at the same position as described above (position of intake air system 2 which is located at the upstream side with respect to throttle valve 7). Fresh air flow quantity control valve 29 is provided in bypass passage 30. The other end of bypass passage 30 is connected with oilmist separator 13. This is a difference point in the second embodiment from the first embodiment. The boost pressure-flow quantity characteristics of PCV valve 28 and fresh air flow quantity control valve 29 are previously adjusted to provide the same characteristics as those denoted by sign B shown in
Valve body 36 includes a flange section 37 formed on a terminal end of valve body 36 located at second port 35 side; and a tipped blowby gas metering section 38 projected from flange section 37 toward first port 34 side. Compressive coil spring 39 interposed between flange section 37 and cover 32 is formed to bias valve body 36 toward second port 35. A blowby gas flow quantity metering section 38 of valve body 36 and throat section 32a on cover 32 are formed in the same way as those described in the first embodiment. A blowby gas flow quantity control orifice 40 which is equal to that described in the first embodiment is formed between throat section 32a and blowby gas metering section 38.
That is to say, in a case where the boost pressure within intake air system 2 is negative, valve body 36 is slidably displaced at the balanced position which is balanced between the boost pressure and the biasing force of compressive coil spring 39. The opening angle of blowby gas flow quantity control orifice 40 and the flow quantity of blowby gas streamed toward intake air system 2 side is variably controlled. On the other hand, in a case where the boost pressure of the intake air system 2 side is positive, flange section 37 of valve body 36 is seated on the bottom wall of valve body main frame 33 to close second port 35. Thus, PCV valve 28 is closed.
Valve body 46 includes a flange section 47 formed on the end of valve body 46 toward first port 44 and a substantially stepped column shaped fresh air metering section 48 projected from flange section 47 to first port 44. Valve body 46 is biased toward first port 44 by means of compressive coil spring 49 intervened between flange section 47 and the bottom wall of valve body main frame 43. Then, fresh air metering section 48 of valve body 46 has large diameter section 48a, middle diameter section 48b, small diameter section 48c, and taper section 48d in the same way as the first embodiment. Then, a fresh air flow quantity control orifice 50 is formed between throat section 43c of a minimum diameter section of second port 45 and small diameter section 48c. Throat section 43c which is the minimum diameter section is formed as the same structure in the first embodiment.
That is to say, in a case where the boost pressure at intake air system 2 side is negative, flange section 47 of valve body 46 is seated on a bottom wall section 42a of cover 42 to close second port 45 so that fresh air flow quantity control valve 29 is closed. On the other hand, in a case where the boost pressure at intake air system 2 side is positive, valve body 46 is slidably displaced at the balanced position at which the boost pressure and the biasing force of compressive coil spring 49 are balanced. Thus, the opening angle of fresh air flow quantity control orifice 50, namely, the flow quantity of fresh air flowing toward oilmist separator 13 is variably controlled. It should be noted that, in a case where the boost pressure in intake air system 2 side is positive, valve body 46 is slidably displaced at the balanced position at which the boost pressure and the biasing force of compressive coil spring 49 are balanced so that the opening angle of fresh air flow quantity control orifice 50, namely, the flow quantity of fresh air streamed toward oilmist separator 13 is variably controlled. It should be noted that a stepped section 48e between large diameter section 48a and middle diameter section 48b of fresh air metering section 48 is seated on the bottom wall of valve body main frame 43 to close second port 45 in the same way as described in the first embodiment.
As described in the second preferred embodiment, while bypass passage 30 is interrupted by means of fresh air flow quantity control valve 29 as shown in
In addition, in a case where the boost pressure of intake air system 2 side is positive and the present engine driving region is in middle load driving region A2 in
Furthermore, in a case of high load driving region A3 shown in
Hence, according to the second preferred embodiment, the same function as in the same way as the first embodiment has been exhibited and fresh air flow quantity control valve 29 which controls the flow quantity of fresh air introduced to crank chamber 1a when the boost pressure at intake air system 2 side is positive is installed in addition to PCV valve 28. Hence, according to the second embodiment, the flow quantity of fresh air introduced into crank chamber 1a can highly accurately be controlled and can stably be controlled.
In the third embodiment, bypass passage 51 having fresh air flow quantity control valve 29 is directly connected with crank chamber is of engine 1 not via oilmist separator 13.
It goes without saying that, in this case, the same function as the second embodiment is exhibited as described above.
This PCV valve 80 has substantially the same structure as PCV valve 12. As shown in
In a case where the boost pressure in intake air system 2 side is positive, valve body 22 pressed by means of the positive pressure is slidably displaced with respect to valve body 17 and valve body 17 comes to stand-still at the position at which the boost pressure and the spring force of second compressive coil spring 27 are balanced.
In a case where fresh air metering section 81 is formed as shown in
Then, in blowby gas reduction passage 10, PCV valve 80 is serially disposed on oilmist separator 13. The boost pressure-flow quantity characteristic of PCV valve 80 by means of flow quantity control orifices 15, 16 is previously adjusted to provide substantially equal characteristic as the characteristic denoted by sign B in
In such a fourth embodiment as described above, in low load driving region A1 shown in
Then, even in this case, since blowby gas flow quantity denoted by sign B exhausted toward intake air system 2 side through blowby gas reduction passage 10 is larger than blowby gas development quantity denoted by sign A in
In such a state as described above, the load of engine becomes large and the boost pressure gradually approaches to the positive side, valve body 22 of PCV valve 80 in
Furthermore, in a positive pressure immediate prior state in which the boost pressure approaches to the positive pressure unlimitedly, the blowby gas flow quantity of sign B exhausted from intake air system 2 side through oilmist separator 13 of blowby gas reduction passage 10 and PCV valve 80 becomes smaller than blowby gas development quantity denoted by sign A and blowby gas is exhausted soon from fresh air introduction passage 11.
As the load of engine 1 becomes furthermore increased and the boost pressure in
Thus, in the driving region in which boost pressure in
Then, in the immediate prior position at which the boost pressure approaches to predetermined set pressure P1 unlimitedly, stepwise section 81d between large diameter section 81a and taper section 81b approaches to the bottom wall of valve body main frame 18 so that the flow passage cross sectional area of fresh air flow quantity control orifice 16 is furthermore made small.
Thus, the flow quantity of fresh air at blowby gas reduction passage 10 denoted by sign C in
When the boost pressure has arrived at predetermined set pressure P1, stepwise section 81d of fresh air metering section 81 as shown in
In the engine ventilation system in the fourth embodiment as described above, importance is placed on the ventilation of crank chamber 1a in the middle driving region and fresh air of constant quantity Q1 is introduced to crank chamber 1a through blowby gas reduction passage 10. In addition, in the high load driving region of engine 1, fresh air is not substantially introduced into crank chamber 1a through blowby gas reduction passage 10, thus importance is placed on the engine output so that much of fresh air can be supplied to the engine, in the region.
In a case where PCV valve 80 is applied, constant flow quantity Q1 set in middle driving region A2 may appropriately be set with the balance between the engine output and the ventilation efficiency taken into consideration.
In addition, fresh air metering section 81 of valve body 22 in PCV valve 80 in the fourth embodiment may be structured as shown in
In a first alternative shown in
In a case where fresh air metering section 91 is formed as shown in
In middle load driving region A2 in
In addition, the flow passage cross sectional area of fresh air flow quantity control orifice 16 is gradually decreased by means of first taper section 91a along with the increase in the boost pressure. However, the boost pressure-flow quantity characteristic of the PCV valve is set so that fresh air at blowby gas reduction passage 10 denoted by sign B in
Therefore, if PCV valve having valve body 22 having such a fresh air metering section 91 as described above is applied, the ventilation efficiency can be improved and the deterioration of engine oil within crank chamber is can be suppressed without output reduction of engine 1 at the time of high load of engine 1 although the boost pressure at the position of intake air system 2 which is located at the downstream side with respect to throttle valve 7 is positive.
It should be noted that, in a case where the PCV valve having valve body 22 having fresh air metering section 91 described above is applied, constant flow quantity Q1 set at middle load driving region A2 and constant flow quantity Q2 set at high load driving region A3 may appropriately be set with the balance between the engine output and high load driving region A3 taken into consideration.
In a second alternative of
In the PCV valve in which valve body 22 having this fresh air metering section 101, second throat section 18a and fresh air metering section 101 are relatively displaced in accordance with the magnitude of positive pressure so that the opening angle formed by both of sections 18a and 101 are variably controlled in the continuous manner and are controlled for the flow quantity of fresh air streamed into PCV valve to be constant irrespective of the magnitude of the positive pressure. It should be noted that, in the PCV valve in which valve body 22 having this fresh air metering section 101, a gap formed between second throat section 18a and fresh air metering section 101 functions as above-described fresh air flow quantity control orifice 16.
In a region from high load driving region A3 to a region in
In the PCV valve in which valve body 22 having fresh air metering section 101 is equipped in the way constructed as described above, the flow passage cross sectional area of fresh air flow quantity control orifice 16 becomes smaller as the boost pressure at position of intake air system which is located at the downstream side with respect to throttle valve 7 becomes larger positive pressure. Hence, it is possible to provide constant flow quantity Q1 for fresh air quantity introduced into crank chamber 1a via the PCV valve even if the boost pressure at the downstream side of throttle valve 7 provides a large positive pressure.
In other words, even if the boost pressure of position of intake air system 2 located at the downstream side with respect to throttle valve 7 indicates the large positive pressure, the quantity of fresh air introduced into crank chamber 1a through the PCV valve in which valve body 22 having fresh air quantity metering section 101 is equipped can provide constant. That is to say, even if the boost pressure at position of intake air system 2 located at the downstream side with respect to throttle valve 7 at the time of high load driving state of engine 1 provides the large positive pressure, fresh air quantity equal to or larger than the constant quantity is not introduced into crank chamber 1a. Hence, at the time of high load state of engine 1, the quantity of fresh air flowing into engine 1 (intake air quantity) is not decreased.
Therefore, in a state in which the boost pressure of position of intake air system 2 located at the downstream side with respect to throttle valve 7 indicates the positive pressure, the ventilation efficiency can be improved and the deterioration of engine oil within crank chamber 1a can be suppressed.
It should be noted that, in a case of the application of the PCV valve in which valve body 22 having fresh air metering section 101 is provided to the ventilation system, constant flow quantity Q1 set at middle load driving region A2 and in high load driving region A3 may appropriately be set with the balance between the engine output and the engine ventilation efficiency of crank chamber 1a taken into consideration.
In the fifth embodiment, in place of PCV quantity control valve 29 described in the second embodiment, fresh air flow quantity control valve 130 which controls the introduction quantity of fresh air from intake air system 2 side to crank chamber 1a is disposed in parallel to PCV valve 28.
The boost pressure-flow quantity characteristics of PCV valve 28 and fresh air flow quantity control valve 130 are previously adjusted to be equal to the characteristic of PCV valve 80 described in the fourth embodiment or to be substantially equal to the characteristic denoted by sign B shown in
Valve body 146 includes: a flange section 147 formed on an end section of valve body 146 faced toward first port 144 side and a fresh air metering section 148 in a substantially taper shape projected from flange section 147 toward second port 145 side. A compressive coil spring 149 interposed between flange section 147 and the bottom wall of valve body main frame 143 biases valve body 146 toward first port 144 side. Then, fresh air metering section 148 of valve body 146 includes: large diameter section 148a, taper section 148b, small diameter section 148c, stepwise section 148d, and a stepwise section 148e. Thus, in the same way as described above, throat section 143a is formed in the same way as the fourth embodiment which is the minimum diameter section of second port 145. Fresh air flow quantity control orifice 150 having the same structure as the fourth embodiment is formed between throat section 143a and second port 145.
In a case where the boost pressure of intake air system 2 side described above is negative, flange section 147 of valve body 146 is seated on bottom wall section 142a of cover 142 so as to close second port 145 and so that fresh air flow quantity control valve 130 is closed. On the other hand, in a case where the boost pressure at intake air system 2 side indicates positive pressure, valve body 46 is slidably displaced at the balanced position at which the boost pressure and the biasing force of compressive coil spring 149 are balanced. Then, in the middle load driving region, the quantity of fresh air streamed from position of intake air system 2 located at the downstream side with respect to throttle valve 7 to blowby gas reduction passage 10 provides the constant quantity irrespective of the boost pressure. Thus, the boost pressure-flow quantity characteristic of fresh air flow quantity control valve 130 is set so that the quantity of fresh air streamed from position of intake air system 2 located at the downstream side of throttle valve 7 becomes substantially zero or extremely small in the high load driving region.
In the fifth embodiment having the structure as described above, in the low load driving region in which the boost pressure at intake air system 2 side is negative, fresh air flow quantity control valve 130 interrupts bypass passage 30 and, on the other hand, the flow quantity of blowby gas exhausted toward intake air system 2 side is controlled by means of PCV valve 28 so that blowby gas reduction passage 10 exhibits the function that this passage naturally has.
In the middle load driving region in which the boost pressure at intake air system 2 side is positive pressure, blowby gas reduction passage 10 is interrupted by means of PCV valve 28 and fresh air of constant flow quantity Q1 metered by means of fresh air flow quantity control valve 130 is introduced into crank chamber is through bypass passage 30. Thus, crank chamber 1a is positively ventilated.
Then, in the high load driving region in which the boost pressure at intake air system 2 side is positive, blowby gas reduction passage 10 is interrupted by means of PCV valve 28 and bypass passage 30 is also interrupted by means of fresh air flow quantity control valve 130.
Hence, even in the fifth embodiment, the same function as described in each of the embodiments can be exhibited. In addition, fresh air flow quantity control valve 29 is additionally installed as is different from PCV valve 28. Hence, the flow quantity of fresh air introduced into crank chamber is can stably be controlled with high accuracy. Especially, in the fifth preferred embodiment, in the high load driving region in which the boost pressure at the intake air system 2 side indicates positive, the quantity of fresh air streamed from the downstream side of throttle valve 7 into blowby gas reduction passage 10 is set to become substantially zero or extremely small. Hence, importance is placed on the high load driving region of the engine so that much of fresh air can be supplied to the engine.
In the fifth embodiment described above, in place of fresh air flow quantity control valve 130, it is possible to use fresh air flow quantity control valve 160 shown in
In the sixth embodiment, the boost pressure-flow quantity characteristics of PCV valve 28 and fresh air flow quantity control valve 160 are previously adjusted to provide the characteristics of PCV valve of valve body 22 having fresh air metering section 101 and to provide the characteristic substantially equal to the characteristic of sign B shown in
Valve body 166 includes a flange section 167 formed on an end section of valve body 166 faced toward first port 164 side and a fresh air metering section 168 in a substantially taper shape projected from flange section 167 toward second port 165 side. A compressive coil spring 169 interposed between flange section 167 and the bottom wall of valve body main frame 163 biases valve body 166 toward first port 164 side. Then, fresh air metering section 168 of valve body 166 includes: taper section 168a; and small diameter section 168b of the column shape. Fresh air metering section 168 is formed in the same way as fresh air metering section 101 in
In a case where the boost pressure of intake air system 2 side is negative, flange section 167 of valve body 166 is seated on bottom wall section 162a of cover 162 so as to close second port 165 and so that fresh air flow quantity control valve 160 is closed. On the other hand, in a case where the boost pressure at intake air system 2 side indicates positive pressure, valve body 166 is slidably displaced at the balanced position at which the boost pressure and the biasing force of compressive coil spring 169 are balanced. Then, the flow passage cross sectional area of fresh air flow quantity control orifice 150 becomes gradually small along with the increase in the boost pressure. Thus, the boost pressure-flow quantity characteristic of fresh air flow quantity control valve 160 is set so that the flow quantity of fresh air streamed to oilmist separator 13 side provides constant flow quantity Q1.
In the sixth embodiment having the structure as described above, in the low load driving region in which the boost pressure at intake air system 2 side is negative, fresh air flow quantity control valve 160 interrupts bypass passage 30 and, on the other hand, the flow quantity of blowby gas exhausted toward intake air system 2 side is controlled by means of PCV valve 28 so that blowby gas reduction passage 10 exhibits the function that this passage naturally has.
In addition, in the middle load driving region and in the high load driving region in which the boost pressure at intake air system 2 side indicates positive, blowby gas reduction passage 10 is interrupted by means of PCV valve 28. Then, fresh air of constant flow quantity Q1 metered by means of fresh air flow quantity control valve 160 is introduced into crank chamber 1a through bypass passage 30. Thus, crank chamber 1a is positively ventilated.
Hence, in the sixth embodiment, the action and advantage can be obtained in the same way as in the case of the fifth embodiment. In the sixth embodiment, fresh air of constant flow quantity Q1 even at high load driving region in which the boost pressure at intake air system 2 side indicates positive is introduced from position of intake air system 2 side located at downstream side with respect to throttle valve 7 into crank chamber is via blowby gas reduction passage 10. Hence, the ventilation efficiency at the time of the high load driving state can be improved without introduction of output reduction of engine 1 at the time of high load and the deterioration of engine oil within crank chamber 1a can be suppressed.
In addition, even in the fifth and sixth embodiments, fresh air flow quantity control valve 110 may directly be communicated with crank chamber 1a of engine 1 not with respect to oilmist separator 13.
The effect of the present invention defined in each of claims 1 and 7 has been described above in the summary of the invention. According to the present invention described in the claim 2 in which a variable orifice functioning as the fresh air flow quantity control means is installed in the blowby gas reduction passage and, in the high load driving region, a flow passage cross sectional area of the variable orifice which functions as the fresh air flow quantity control means is at least made smaller than the flow passage cross sectional area in the middle load driving region, since fresh air is introduced into the crank chamber utilizing a known passage, it becomes advantageous in terms of simplification of structure.
According to the present invention described in the claim 3 in which the PCV valve includes a variable orifice functioning as the fresh air flow quantity control means apart from another variable orifice for a blowby gas flow quantity control that the PCV valve naturally has, since a slight improvement is added to well known PCV valve to enable the achievement in the object of the present invention, it becomes more advantageous in terms of simplification of structure.
On the other hand, according to the present invention described in the claim 4, the variable orifice which functions as the fresh air flow quantity control means is installed in addition to the PCV valve and the flow quantity introduced into the crank chamber is controlled according to the variable orifice. Thus, the flow quantity of fresh air introduced into the crank chamber can stably be controlled with high accuracy.
According to the present invention described in the claim 5, the introduction of fresh air to the crank chamber in the high load driving region is stopped so that the output reduction of the engine can effectively be suppressed.
Then, according to the present invention described in the claim 6 in which a flow quantity of fresh air from position of the intake air passage which is located at the downstream side with respect to the throttle valve to the crank chamber, in the middle load driving region (A2), is constant and, in the high load driving region (A3), the flow quantity of fresh air from position of the intake air passage which is located at the downstream side with respect to the throttle valve is made equal to the flow quantity in the middle load driving region, in a state in which the boost pressure of position of the intake air passage located at the downstream side with respect to the throttle valve indicates positive, the quantity of fresh air introduced from position of intake air passage located at the downstream side with respect to the throttle valve does not provide the constant quantity or larger. Hence, the ventilation efficiency can be improved without introduction of engine output and the deterioration of engine oil within the crank chamber can be suppressed.
This application is based on a prior Japanese Patent Application No. 2010-285450 filed in Japan on Dec. 22, 2010 and No. 2010-137849 filed in Japan on Jun. 17, 2010. The entire contents of these Japanese Patent Applications of No. 2010-285450 and No. 2010-137849 are hereby incorporated by reference. Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art in light of the above teachings. The scope of the invention is defined with reference to the following claims.
Number | Date | Country | Kind |
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2010-137849 | Jun 2010 | JP | national |
2010-285450 | Dec 2010 | JP | national |