US 6,550,445 B2Granted

Spark-ignition direct injection engine with supercharger

AssigneeMazda Motor Corporation

InventorsKazuaki Umezono, Hiroyasu Uchida, Mikihito Fujii

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Abstract

A spark-ignition type 4-cycle direct injection engine is provided with a turbocharger for boosting intake air and an injector for directly injecting fuel to a combustion chamber within a cylinder, wherein in a λ=1 region (II) and an enriched region (III) on the high-speed high-load side, fuel is injected during the intake stroke of the cylinder to attain a state of homogenous combustion. When the engine is in the high-speed side (specific region) of the enriched region (III), the air-fuel ratio A/F of the air-fuel mixture in the cylinder is controlled to become A/F≦13, the tumble flow T is strengthened by closing the TSCVs, and the opening degree of a wastegate valve of the turbocharger is controlled in order to increase the maximum boost pressure and compensate the drop in intake efficiency that is caused by closing the TSCVs. Thus, in the high-speed side of the enriched region (III), a maximum output of the engine is ensured and the dependability of the exhaust system is secured while the PM in the exhaust can be decreased.

Claims7

Dependent claims

A spark-ignition type 4-cycle direct injection engine, comprising a supercharger for boosting intake air into a cylinder and a fuel injection valve for directly injecting and supplying fuel to a combustion chamber within the cylinder, wherein in at least a supercharge region on a high-speed high-load side, fuel is injected during an intake stroke of the cylinder by the fuel injection valve to attain a state of homogenous combustion, the spark-ignition type 4-cycle direct injection engine comprising:

a flow strengthening means for constricting the flow of intake air into the cylinder and strengthening a flow within the cylinder;
a boost pressure adjustment means for keeping a boost pressure of the intake air due to the supercharger below a target boost pressure;
an air-fuel ratio control means for controlling an air-fuel ratio A/F in the cylinder so that A/F≦13 in a specific driving region that is established on the high-speed high-load side within the supercharge region;
a flow control means for increasing the amount of constriction on the intake air with the flow strengthening means, so as to relatively strengthen the flow in the cylinder in the specific driving region as compared to that in a region that is adjacent to a low-load side of the specific driving region, even if an engine revolution speed is the same;
and
a boost pressure control means for controlling the boost pressure adjustment means to relatively increase the target boost pressure in the specific driving region as compared to that in a region that is adjacent to a low-speed side of the specific driving region.

3 more elements

A spark-ignition type 4-cycle direct injection engine, comprising a fuel injection valve for directly injecting and supplying fuel to a combustion chamber within a cylinder, a turbocharger for receiving exhaust from the combustion chamber and boosting it, and a controller for injecting fuel with the fuel injection valve during an intake stroke of the cylinder so as to attain a state of homogenous combustion in at least a supercharge region on a high-speed high-load side, the spark-ignition type 4-cycle direct injection engine comprising:

a flow control valve that is disposed in an intake passage to the cylinder;
and
a relief valve for bypassing a portion of the exhaust from the combustion chamber to a downstream side of the turbocharger to keep a boost pressure of the intake air below a target boost pressure;
wherein the controller, in a specific driving region that is established at the high-speed high-load side within the supercharge region, controls a volume of fuel injected by the fuel injection valve so that an air-fuel ratio A/F in the cylinder becomes A/F≦13, and
the controller is configured to control an opening degree of the flow control valve in order to relatively strengthen the flow in the cylinder as compared to that in a driving region that is adjacent to a low-load side of the specific driving region, even if an engine revolution speed is the same, and moreover control an opening degree of the relief valve in order to relatively increase the target boost pressure as compared to that in a driving region that is adjacent to a low-speed side of the specific driving region.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/195,306Filed 16 Jul 2002
Priority: JP 2001-21647917 Jul 2001
Published: US 2003/0024499 A16 Feb 2003
Granted: 22 Apr 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

F02B 31/085
Having multiple air inlets: having two inlet valves
F02D 41/3029
A mode being the stratified charge spark-ignited mode: further comprising a homogeneous charge spark-ignited mode
F02B 2075/125
Other methods of operation: direct injection in the combustion chamber for spark ignition engines, i.e. not in pre-combustion chamber
F02D 41/187
By measuring intake air flow: using a hot wire flow sensor