1. An EGR cooler comprising,
a core in which a flat first flow passage and a second flow passage are alternately arranged side by side, a casing fitted to the outer periphery of the core, and header portions of an exhaust gas arranged at both ends of the casing in the longitudinal direction, wherein
a bypass duct portion is formed between the inner surface of the casing and the core, and a switch is provided for switching and guiding the exhaust gas to either of the core or the bypass duct portion.
2. The EGR cooler according to claim 1, wherein
the one header portion communicates with both the core and the bypass duct portion and is provided with one port; and
the other header portion has a partition plate inside separating the core and the bypass duct portion from each other, and two ports are formed on both sides with the partition plate as the boundary.
3. The EGR cooler according to claim 1 or 2, wherein
said bypass duct portion of said casing is bent with a cross section in an arc state,
a heat stress absorbing portion is provided in which a large number of inner ribs or outer ribs are arranged side by side in the circumferential direction while being separated from each other in the longitudinal direction, and
cooling water is guided to the first flow passage of the core and the exhaust gas is guided to the second flow passage.
4. The EGR cooler according to claim 3, wherein
a partition plate is provided at the boundary between said core and said bypass duct portion, and both ends of the ribs are formed only on the bypass duct portion side rather than the partition plate so as not to cross the edge portion of the partition plate.
5. The EGR cooler according to claim 2, wherein
an opening of an integrally formed cylindrical valve case by deep-drawing of a thin metal plate by a press machine is brazedfixed to an opening of said other header portion,
an intra-valve partition plate dividing the valve case into two parts is brazedfixed inside said valve case, a rear-end edge portion of the intra-valve partition plate is brazed to a tip end edge portion of the partition plate, a pair of slits conforming to the plate thickness of said intra-valve partition plate are provided at the rear end of said valve case, both edges of the intra-valve partition plate are inserted into the slits, and support projection portions are formed on both faces of the both edge portions of the intra-valve partition plate so that they support the inner edges of said slits,
a valve shaft is inserted into the valve case, and a core openingclosing valve and a bypass openingclosing valve are fixed to the respective valve shaft and provided on both sides of said intra-valve partition plate so as to cross perpendicularly each other so that the cooling water is guided to the first flow passage of said core and the high-temperature exhaust gas is made to selectively communicate with the second flow passage side and said bypass duct portion side of said core through rotating driving of said valve shaft.
6. The EGR cooler according to claim 5, wherein
the outer periphery of the valve case is formed with a substantially rectangular section and a flat center part at each of four peripheries except a tip-end opening edge portion, the tip-end edge portion has a swollen portion with a small oval section with the entire both sides formed by projecting curved faces, its tip-end edge portion conforms to the opening of the header portion, and they are fitted with each other and brazedfixed, and
said valve shaft is inserted into the side of said substantially rectangular section of the valve case.
7. The EGR cooler according to claim 5 or 6, wherein
a reinforcing body made of a press formed body of a metal plate thicker than the plate thickness of said valve case and having a flange portion adjacent to the tip-end opening edge portion of the valve case is provided, a side edge portion extended integrally from the peripheral edge of the flange portion is brazed to the outer face of the tip end portion of said casing, and a valve driving body is mounted to said side edge portion of the reinforcing body.
8. The EGR cooler according to any of claims 1, 2, 5 or 6, wherein
in said core, a core body is formed in which a strip-shaped metal plate is turned up and bent in a fanfold manner with turned-up end edges alternately formed at one end and the other end of a rectangular flat face portion and flat first flow passages and second flow passages are provided alternately in the thickness direction of the metal plate,
the first flow passages of the core body is blocked by a comb-state member made of an elongated plate material or rod material at both end positions of said turned-up end edge, and a fin is set within said second flow passages,
the outer periphery of the core body is fitted with the cylindrical casing so as to block the adjacent turned-up end edges,
the first fluid is guided to each of the first flow passages by a pair of ports on the outer face of said casing, while the second fluid is guided from one of cylindrical openings of said casing to the other opening through each of the second flow passages.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An engine mode control module for an internal combustion engine comprising:
a transition control module that controls a transition from a first engine mode to a second engine mode and that determines a desired air mass, wherein the engine is operated at a first airfuel ratio (AFR) in the first engine mode and at a second AFR in the second engine mode and the desired air mass is based on the second AFR; and
an intake cam phaser control module that adjusts the intake cam phaser based on the desired air mass during the transition.
2. The engine mode control module of claim 1 further comprising a throttle control module that maintains a throttle plate at a first position during a first stage of the transition, wherein the first position is based on the first AFR.
3. The engine mode control module of claim 2 wherein the throttle control module controls the throttle plate from the first position to a desired throttle position during a second stage of the transition, wherein the desired throttle position is based on the desired air mass and the second stage occurs after the first stage.
4. The engine mode control module of claim 3 wherein an actual air mass remains constant when the throttle plate is moved from the first position to the desired throttle position.
5. The engine mode control module of claim 3 wherein the intake cam phaser control module adjusts the intake cam phaser to an original position when the throttle plate is moved from the first position to the desired throttle position.
6. The engine mode control module of claim 1 further comprising a fuel injection control module that initiates dual injections in an engine cycle during the transition.
7. The engine mode control module of claim 6 wherein the dual injections include a first injection in an intake stroke and a second injection in a compression stroke.
8. The engine mode control module of claim 1 further comprising an ignition control module that adjusts spark timing to control an actual AFR.
9. The engine mode control module of claim 1 wherein the intake cam phaser is advanced in a first stage of the transition when the engine is transitioned from a homogeneous mode to a stratified mode.
10. The engine mode control module of claim 9 further comprising a spark control module that retards a spark plug to maintain an actual AFR at a stoichiometric ratio in the first stage of transition.
11. The engine mode control module of claim 1 wherein the intake cam phaser is retarded in a first stage of transition when the engine is transitioned from a stratified mode to a homogenous mode.
12. The engine mode control module of claim 11 wherein the spark timing is controlled to gradually increase an actual AFR.
13. A method comprising:
controlling a transition from a first engine mode to a second engine mode, wherein an engine is operated at a first airfuel ratio (AFR) in the first engine mode and at a second AFR in the second engine mode;
determining a desired air mass based on the second AFR; and
adjusting an intake cam phaser based on the desired air mass.
14. The method of claim 13 further comprising maintaining a throttle plate at a first position during a first stage of the transition, wherein the first position is based on the first AFR.
15. The method of claim 14 further comprising moving the throttle plate from the first position to a desired throttle position during a second stage of the transition, wherein the desired throttle position is based on the desired air mass and the second stage occurs after the first stage.
16. The method of claim 15 wherein the throttle plate is moved to the desired throttle position after the engine is operated at the second AFR.
17. The method of claim 16 further comprising adjusting the intake cam phaser based on an actual throttle position to maintain the desired air mass.
18. The method of claim 13 further comprising initiating dual injections in an engine cycle during the transition.
19. The method of claim 13 further comprising advancing an intake cam phaser when the engine is transitioned from a homogenous mode to a stratified mode.
20. The method of claim 13 further comprising retarding spark timing during the transition.