Internal-combustion engines – Engine speed regulator – Responsive to deceleration mode
Reexamination Certificate
1999-11-02
2001-12-04
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Engine speed regulator
Responsive to deceleration mode
C123S568140
Reexamination Certificate
active
06325043
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to exhaust gas recirculation apparatuses (EGR devices) that recirculate a portion of the exhaust gas together with aspirated air and send it into the combustion chamber in such a way as to lower the combustion temperature within said combustion chamber, thereby working to reduce NO
x
(nitrogen oxides).
BACKGROUND OF THE INVENTION
Conventional exhaust gas recirculation apparatuses are made in such a way that they connect the exhaust pipe and intake port by external piping and open a normally closed EGR valve provided in the path of said external piping using vacuum pressure within the intake port during the intake stroke, thereby causing exhaust gas to recirculate through the above-noted external piping.
However, it turns out that always taking exhaust gas into the combustion chamber on the intake stroke causes lean combustion in conventional exhaust gas recirculation apparatuses as described above, and even though a satisfactory combustion situation can be obtained without difficulty in the light-load operating range in which there is naturally an excess of air, there are problems in that, in the high-load operating range in which the proportion of air with respect to fuel is low, combustion conditions are not good and black smoke with large amounts of soot is readily generated.
Further, because it becomes necessary that the external piping be provided with an EGR valve, the installation space required for the engine increases in volume, and moreover, there is a problem in that careful consideration must be given to providing heat-insulating measures for the external piping which will reach high temperatures as a result of the flow of exhaust gas and to constraints in terms of layout.
In addition, there are also problems in engines equipped with turbochargers, etc., in that exhaust gas cannot be recirculated satisfactorily in operating ranges in which the boost pressure (supercharging pressure within the intake pipe) is higher than the exhaust pressure.
This invention takes these actual circumstances described above in consideration and makes its objective to provide an exhaust gas recirculation apparatus that can recirculate exhaust gas into the combustion chamber only in required operating ranges, and moreover, can recirculate exhaust gas into the combustion chamber without using external piping, and further, in engines equipped with turbochargers, etc., can recirculate exhaust gas acceptably even in operating ranges in which the boost pressure is higher than the exhaust pressure.
SUMMARY OF THE INVENTION
This invention is related to exhaust gas recirculation apparatuses characterized in that they are provided with an exhaust gas recirculation master piston activated by an intake rocker arm that acts to open an intake valve on a cylinder on the intake stroke; a slave piston connected via a first oil passage to said exhaust gas recirculation master piston, and further, that acts to open the aforementioned intake valve and an exhaust valve provided on the same cylinder when pressure is generated in said first oil passage by the action of the aforementioned exhaust gas recirculation master piston; a hydraulic oil supply means that switches between maintaining and releasing oil pressure in the aforementioned first oil passage; a compression pressure-release engine brake master piston activated by an exhaust rocker arm that acts to open an exhaust valve on the cylinder on the exhaust stroke; a slave piston connected via a second oil passage to said compression pressure-release engine brake master piston, and further, when pressure has been generated in said second oil passage by the action of the aforementioned compression pressure-release engine brake master piston, that acts to open an exhaust valve provided separately from the aforementioned exhaust valve on a cylinder approaching compression top dead center; and, a hydraulic oil supply means that switches between maintaining and releasing oil pressure in the aforementioned second oil passage.
Thus, when oil pressure in the first oil passage is maintained by means of the hydraulic oil supply means, the exhaust gas recirculating master piston is activated by the exhaust rocker arm on the intake stroke, pressure is generated in the first oil passage, the exhaust valve on the same cylinder is made to open by the slave piston being driven, and exhaust gas recirculates from the exhaust port into the combustion chamber as a result of the pressure difference, thereby lowering the combustion temperature within the combustion chamber on the next power stroke and working to reduce NO
x
.
In addition, when oil pressure in the first oil passage is released by means of the hydraulic oil supply means, no oil pressure is generated within the first oil passage, the slave piston is not driven, and the exhaust valve opens only on the exhaust stroke as a result of normal valve action and does not open on the intake stroke.
Further, by selectively maintaining and releasing oil pressure in the first oil passage and the second oil passage, it becomes possible to switch between exhaust gas recirculation mode and compression pressure-release engine braking mode. For example, during braking operation, whenever oil pressure is released in the first oil passage, and further, oil pressure is maintained in the second oil passage, as each respective cylinder approaches compression top dead center with different timings, the compression pressure-release engine brake master piston is activated by the exhaust rocker arm in order to open the exhaust valve of a separate cylinder which is on the exhaust stroke. Pressure is generated in the second oil passage, the slave piston is driven and the exhaust valve of the cylinder is made to open near compression top dead center, compressed air from within the combustion chamber is allowed to pass into the exhaust port, power to push down the piston on the following expansion stroke is no longer generated, and it becomes possible to use it effectively without losing the braking force gained on the compression stroke.
It should also be noted that it is possible to combine the salve piston operated by oil pressure from the first oil passage and the salve piston operated by oil pressure from the second oil passage, and in addition, it is also acceptable that they be provided separately.
In addition, this invention is also related to exhaust gas recirculation apparatuses characterized in that they are provided with an exhaust gas recirculation master piston activated by an exhaust rocker arm that acts to open an exhaust valve on a cylinder on the exhaust stroke; a slave piston connected via a first oil passage to said exhaust gas recirculation master piston, and further, that acts to open the aforementioned exhaust valve and an intake valve provided on the same cylinder when pressure is generated in said first oil passage by the action of the aforementioned exhaust gas recirculation master piston; a hydraulic oil supply means that switches between maintaining and releasing oil pressure in the aforementioned first oil passage; a compression pressure-release engine brake master piston activated by an exhaust rocker arm that acts to open an exhaust valve on a cylinder on the exhaust stroke; a slave piston connected via a second oil passage to said compression pressure-release engine brake master piston, and further, when pressure has been generated in said second oil passage by the activation of the aforementioned compression pressure-release engine brake master piston, that acts to open an exhaust valve provided separately from the aforementioned exhaust valve on a cylinder approaching compression top dead center; and, a hydraulic oil supply means that switches between maintaining and releasing oil pressure in the aforementioned second oil passage.
Thus, when oil pressure is maintained in the first oil passage by means of the hydraulic oil supply means, the exhaust gas recirculating master piston is activated by the exhaust rocker arm on the exhaust stroke, pressure is generated
Maeda Yoshihide
Meistrick Zdenek
Pitzi Vincent
Castro Arnold
Collier Shannon Scott PLLC
Hino Jidosha Kabushiki Kaisha
Yohannan David R.
Yuen Henry C.
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