# US 11,028,791 B2 · Method and system for matching air flow in an exhaust gas recirculation system

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- Number: US 11,028,791 B2
- Document ID: US11028791B2
- Status: Granted
- Kind: B2
- Application number: 16/721,725
- Filed: 2019-12-19
- Published: 2020-04-23
- Granted: 2021-06-08
- Earliest claimed: 2012-07-13
- Assignees: Transportation IP Holdings, LLC
- Applicants: Transportation IP Holdings, LLC
- Inventors: James Henry Yager
- Web page: https://patentgrep.com/patent/US11028791B2

## CPC

- F02D 41/0047: {Controlling exhaust gas recirculation [EGR] (temperature control with cooler in recirculation circuit F02M26/33)}
- F02B 29/0412: {Multiple heat exchangers arranged in parallel or in series}
- F02B 37/004: {with exhaust drives arranged in series}
- F02B 37/18: by bypassing exhaust {from the inlet to the outlet of turbine or to the atmosphere}
- F02D 13/0261: {Controlling the valve overlap}
- F02D 41/0082: {per groups or banks (F02D41/0087 takes precedence)}
- F02D 2041/001: {for engines with variable valve actuation}
- F02M 26/08: for engines having two or more intake charge compressors or exhaust gas turbines, e.g. a turbocharger combined with an additional compressor
- 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
- F02M 26/19: Means for improving the mixing of air and recirculated exhaust gases, e.g. venturis or multiple openings to the intake system
- F02M 26/25: with coolers having bypasses
- F02M 26/43: in which exhaust from only one cylinder or only a group of cylinders is directed to the intake of the engine
- Y02T 10/40: Engine management systems
- F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W)
- F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G)
- F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

Various methods and systems are provided for an exhaust gas recirculation system. In one embodiment, an engine method comprises routing exhaust gas from a first cylinder group of an engine to an exhaust gas recirculation passage coupled to both an intake passage and an exhaust passage of the engine, the first cylinder group having a first amount of positive intake and exhaust valve overlap, and routing exhaust gas from a second cylinder group of the engine only to the exhaust passage of the engine, the second cylinder group having a second, smaller amount of positive intake and exhaust valve overlap.

## Claims

### Claim 1

An engine system, comprising:
a first cylinder group coupled exclusively to an exhaust gas recirculation passage configured to route exhaust to an intake passage and an exhaust passage of the engine;
a second cylinder group coupled exclusively to the exhaust passage of the engine, wherein the intake passage is configured to route exhaust from the exhaust gas recirculation passage to both the first cylinder group and the second cylinder group;
a first camshaft having cam lobes with a first profile to close exhaust valves of the first cylinder group at a first timing; and
a second camshaft having cam lobes with a second profile to close exhaust valves of the second cylinder group at a second timing, the second timing earlier than the first timing, wherein the exhaust valves of the first cylinder group are closed at the first timing during all operating conditions where exhaust valve events are occurring.

### Claim 2 (depends on 1)

The system of claim 1, wherein the exhaust valves of the first cylinder group closing at the first timing and the exhaust valves of the second cylinder group closing at the second timing results in the exhaust valves of the second cylinder group being open for a shorter duration than the exhaust valves of the first cylinder group.

### Claim 3 (depends on 1)

The system of claim 1, wherein each cylinder of the first cylinder group has a higher compression ratio than each cylinder of the second cylinder group.

### Claim 4 (depends on 1)

The system of claim 1, wherein the first profile of the cam lobes of the first camshaft open the exhaust valves of the first cylinder group with a first amount of valve lift, and wherein the second profile of the cam lobes of the second camshaft open the exhaust valves of the second cylinder group with a second amount of valve lift that is different than the first amount of valve lift.

### Claim 5 (depends on 1)

The system of claim 1, further comprising a first valve configured to route exhaust from the first cylinder group to the exhaust passage and a second valve configured to route exhaust from the first cylinder group to the intake passage.

### Claim 6 (depends on 5)

The system of claim 5, further comprising a control unit storing instructions executable to adjust a position of the first valve and/or a positon of the second valve based on a target amount of exhaust gas recirculation.

### Claim 7 (depends on 6)

The system of claim 6, wherein the instructions are further executable to determine the target amount of exhaust gas recirculation based on engine speed and/or engine load.

### Claim 8 (depends on 1)

The system of claim 1, wherein the first cylinder group is arranged into a first cylinder bank and the second cylinder group is arranged into a second cylinder bank, thereby forming a V engine, and wherein the first camshaft is coupled to the first cylinder bank and the second camshaft is coupled to the second cylinder bank.

### Claim 9

An engine system, comprising:
a first cylinder group coupled exclusively to an exhaust gas recirculation passage configured to route exhaust to an intake passage and an exhaust passage of the engine;
a second cylinder group coupled exclusively to the exhaust passage of the engine; and
a control unit storing instructions executable to:
responsive to a first condition including an exhaust backpressure of the first cylinder group exceeding an exhaust backpressure of the second cylinder group, operate the first cylinder group with a first amount of positive intake and exhaust valve overlap;
responsive to a second condition including the exhaust backpressure of the first cylinder group being equal to the exhaust backpressure of the second cylinder group, operate the first cylinder group with a second, smaller amount of positive intake and exhaust valve overlap; and
responsive to the first condition and responsive to the second condition, operate the second cylinder group with the second, smaller amount of positive intake and exhaust valve overlap.

### Claim 10 (depends on 9)

The system of claim 9, further comprising a first valve configured to route exhaust from the first cylinder group to the exhaust passage and a second valve configured to route exhaust from the first cylinder group to the intake passage.

### Claim 11 (depends on 10)

The system of claim 10, wherein the instructions are executable to adjust a position of the first valve and/or a positon of the second valve based on a target amount of exhaust gas recirculation.

### Claim 12

A method, comprising:
during a first condition, routing exhaust gas from a first cylinder group of an engine to an exhaust gas recirculation passage coupled to both an intake passage and an exhaust passage of the engine, and closing exhaust valves of the first cylinder group at a first timing;
during the first condition, routing exhaust gas from a second cylinder group of the engine only to the exhaust passage of the engine and closing exhaust valves of the second cylinder group at a second timing, the second timing earlier than the first timing; and
adjusting a position of a first valve configured to route exhaust from the first cylinder group to the exhaust passage and a position of a second valve configured to route exhaust from the first cylinder group to the intake passage based on a target amount of exhaust gas recirculation.

### Claim 13 (depends on 12)

The method of claim 12, further comprising routing exhaust gas from the exhaust gas recirculation passage to both the first cylinder group and the second cylinder group via the intake passage.

### Claim 14 (depends on 12)

The method of claim 12, wherein the first condition includes an exhaust backpressure of the first cylinder group exceeding an exhaust backpressure of the second cylinder group.

### Claim 15 (depends on 14)

The method of claim 14, further comprising, responsive to a second condition including the exhaust backpressure of the first cylinder group being equal to the exhaust backpressure of the second cylinder group, closing the exhaust valves of the first cylinder group at the second timing.

### Claim 16 (depends on 12)

The method of claim 12, further comprising opening the exhaust valves of the first cylinder group with a first amount of valve lift, and opening the exhaust valves of the second cylinder group with a second amount of valve lift that is different than the first amount of valve lift.

### Claim 17 (depends on 12)

The method of claim 12, further comprising determining the target amount of exhaust gas recirculation based on engine speed and/or engine load.