Pneumatically controlled exhaust throttle for delivering EGR on turbocharged engines

• US 6,321,536 B1
• Filed: 12/07/2000
• Issued: 11/27/2001
• Est. Priority Date: 12/07/2000
• Status: Active Grant

• Current Assignee: Cummins Incorporated
• Original Assignee: Cummins Incorporated
• Inventors: Henry, Scott A., Henderson, Gregory H.
• Primary Examiner(s): NGUYEN, HOANG M
• Application Number:
  US09/732,261
• Time in Patent Office: 355 Days
• Field of Search: 606/052, 606/11, 123/568.11
• US Class Current: 60/605.2
• CPC Class Codes: F02B 37/22 by varying cross-section of exhaust passages or air passages , e.g. by throttling turbine inlets or outlets or by varying effective number of guide conduits F02B37/24 takes precedence
• CPC Class Codes: F02D 9/04 concerning exhaust conduits throttle valves, or arrangements thereof in conduits F02D9/08
• CPC Class Codes: F02M 26/05 High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
• CPC Class Codes: F02M 26/10 having means to increase the pressure difference between the exhaust and intake system, e.g. venturis, variable geometry turbines, check valves using pressure pulsations or throttles in the air intake or exhaust system
• CPC Class Codes: F02M 26/19 Means for improving the mixing of air and recirculated exhaust gases, e.g. venturis or multiple openings to the intake system
• CPC Class Codes: F02M 26/23 Layout, e.g. schematics
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A pneumatic throttle system for maintaining sufficient exhaust pressure to maintain exhaust flow through an EGR system. The throttle system includes an apertured throttle plate positioned to selectively restrict the flow of exhaust gasses exiting the engine. Movement of the plate is controlled by a pneumatic piston assembly connected thereto. The piston assembly includes a piston movably mounted within a gas-tight chamber. The piston head functionally divides the chamber into two variable-volume portions. The first chamber portion is pneumatically connected to the intake manifold, while the second portion is pneumatically connected to the exhaust manifold. The gas pressure in one chamber portion relative the other determines the relative volume of each chamber portion according to P₁V₁=P₂V₂. The piston moves within the chamber to satisfy the above relationship. As the piston moves in response to changes in the respective manifold pressures, the throttle plate moves to increase or decrease gas flow therethrough, accordingly changing the exhaust back-pressure.

Claims

1. A pneumatic throttle system, comprising:

an engine having an intake manifold and an exhaust manifold;

a throttle plate operative to restrict gas flow from the exhaust manifold, positioned in pneumatic communication with the exhaust manifold; and

a pneumatic actuator assembly further comprising;

a housing having an air intake portion and an exhaust portion;

a piston head movably positioned in the housing and separating the intake and exhaust portions;

a piston tail portion extending from the piston head portion and operationally connected to the throttle plate;

a first gas inlet formed in the intake portion; and

a second gas inlet formed in the exhaust portion;

wherein the first gas inlet is pneumatically connected to the intake manifold;

wherein the second gas inlet is pneumatically connected to the exhaust manifold;

wherein the piston head moves in the housing in response to changes in intake manifold pressure relative to exhaust manifold pressure; and

wherein movement of the piston actuates operation of the throttle plate.

2. The system of claim 1 wherein the throttle plate is adapted to open and close, wherein opening of the throttle plate decreases exhaust manifold pressure, and wherein closure of the throttle plate increases exhaust manifold pressure.

3. The system of claim 1, wherein the intake portion has a variable intake portion volume, wherein the exhaust portion has a variable exhaust portion volume, wherein the sum of the intake portion volume and the exhaust portion volume is a constant;

wherein movement of the piston head in response to an increase in intake manifold pressure relative to exhaust manifold pressure increases the relative volume of the intake portion and actuates the throttle plate to increase exhaust manifold pressure; and

wherein movement of the piston head in response to a decrease in intake manifold pressure relative to exhaust manifold pressure decreases the relative volume of the intake portion and actuates the throttle plate to decrease exhaust manifold pressure.

4. The system of claim 1 further comprising an exhaust gas recirculation system pneumatically connected between the exhaust gas manifold and the intake manifold.

5. The system of claim 4 wherein the exhaust gas recirculation system includes an exhaust gas cooler in fluidic communication with the exhaust manifold and the intake manifold.

6. An engine exhaust system, comprising:

an engine;

an air intake manifold having an intake manifold pressure and positioned in fluidic communication with the engine;

an exhaust manifold having an exhaust manifold pressure and positioned in fluidic communication with the engine;

a compressor in fluidic communication with the air intake manifold;

an exhaust port in fluidic communication with the exhaust manifold;

a throttle plate fluidically connected between the exhaust manifold and the exhaust port;

an exhaust gas recirculator fluidically connected between the exhaust manifold and the intake manifold; and

a pneumatic control actuator fluidically connected to the intake manifold and to the exhaust manifold and operationally connected to the throttle plate;

wherein the throttle plate is adapted to open and close;

wherein an increase in intake manifold pressure relative to exhaust manifold pressure actuates closure of the throttle plate;

wherein a decrease in intake manifold pressure relative to exhaust manifold pressure actuates opening of the throttle plate;

wherein closure of the throttle plate increases exhaust manifold pressure; and

wherein opening of the throttle plate decreases exhaust manifold pressure.

7. The engine exhaust system of claim 6 wherein the pneumatic control actuator is adapted to automatically control the throttle plate in response to a change in the ratio of intake manifold pressure to exhaust manifold pressure.

8. The engine exhaust system of claim 6 wherein the pneumatic control actuator comprises:

an intake portion having a variable size;

an exhaust portion having a variable size; and

a piston head separating the intake portion and the exhaust portion and operationally connected to the throttle plate;

wherein the intake portion is maintained at substantially the intake manifold pressure;

wherein the exhaust portion is maintained at substantially the exhaust manifold pressure; and

wherein the piston head is adapted to move in response to a change in the ratio of intake manifold pressure to exhaust manifold pressure.

9. A mechanical system comprising:

an exhaust manifold having an exhaust manifold pressure;

an exhaust gas conduit connecting the exhaust gas manifold to the atmosphere;

a throttle positioned in the exhaust gas conduit between the exhaust gas manifold and the atmosphere;

an intake manifold having an intake manifold pressure; and

a pneumatic actuator assembly further comprising;

a first chamber portion having a first volume pneumatically connected to the intake manifold;

a second chamber portion having a second volume pneumatically connected to the exhaust manifold;

a piston head movably positioned between the first and second chambers and operationally connected to the throttle;

wherein the sum of the first and second volumes is substantially constant;

wherein the first and second volumes are functions of the intake manifold pressure and the exhaust manifold pressure;

wherein changes in the first and second volumes actuates movement of the piston head; and

wherein movement of the piston head actuates movement of the throttle.

10. The mechanical system of claim 9 wherein the movement of the throttle is automatically actuated by a change in the intake manifold pressure relative to exhaust manifold pressure.

11. The mechanical system of claim 9 wherein an increase in the first volume actuates operation of the throttle to restrict gas flow therethrough and to increase the exhaust manifold pressure.

12. The mechanical system of claim 9 wherein an increase in the second volume actuates operation of the throttle to increase gas flow therethrough and to decrease the exhaust manifold pressure.

13. The mechanical system of claim 9 wherein the piston head moves such that the product of the first volume and the intake manifold pressure is substantially equal to the product of the second volume and the exhaust manifold pressure.

14. The mechanical system of claim 9 further comprising an exhaust gas recirculation system pneumatically connected between the exhaust gas manifold and the intake manifold.

15. A method of regulating the exhaust manifold pressure of an internal combustion engine, comprising the steps of:

a) providing an internal combustion engine having an air intake and an exhaust manifold, wherein the exhaust manifold emits exhaust gasses when the engine is running;

b) providing a throttle adapted to selectively restrict the flow of exhaust gasses from the exhaust manifold;

c) providing an automatic pneumatic controller pneumatically connected to the intake manifold and to the exhaust manifold and operationally connected to the throttle;

d) circulating exhaust gasses from the exhaust manifold into the controller;

e) restricting the flow of the exhaust gasses when the ratio of the intake manifold pressure to the exhaust manifold pressure increases; and

f) increasing the flow of exhaust gasses when the ration of the intake manifold pressure tot the exhaust manifold pressure decreases.

16. The method of claim 15 wherein the controller includes:

a first portion of variable volume pneumatically connected to the intake manifold;

a second portion of variable volume pneumatically connected to the exhaust manifold; and

a movable divider separating the first and second portions and operationally connected to the throttle;

wherein the sum of the variable volumes of the first and second portions is substantially constant;

wherein an increase in intake manifold pressure relative to exhaust manifold pressure actuates an increase in the volume of the first portion and a corresponding decrease in the volume of the second portion; and

wherein an increase in exhaust manifold pressure relative to intake manifold pressure actuates an increase in the volume of the second portion and a corresponding decrease in the volume of the first portion.

17. The method of claim 16 wherein an increase in the volume of the first portion and a corresponding decrease in the volume of the second portion actuates movement of the divider towards the second portion;

wherein movement of the divider towards the second portion actuates the throttle to decrease gas flow therethrough, wherein an increase in the volume of the second portion and a corresponding decrease in the volume of the first portion actuates movement of the divider toward the first portion; and

wherein movement of the divider towards the first portion actuates the throttle to increase gas flow therethrough.