# US 10,119,444 B2 · Exhaust management strategies for opposed-piston, two-stroke engines

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- Number: US 10,119,444 B2
- Document ID: US10119444B2
- Status: Granted
- Kind: B2
- Application number: 14/378,252
- Filed: 2013-02-19
- Published: 2015-02-05
- Granted: 2018-11-06
- Earliest claimed: 2012-02-21
- Assignees: Achates Power, Inc.
- Applicants: Achates Power, Inc.
- Inventors: Christopher J. Kalebjian; Suramya D. Naik; Fabien G. Redon
- Web page: https://patentgrep.com/patent/US10119444B2

## CPC

- F01N 3/2006: {Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating (by electrically controlling the supply of combustible mixture or its constituents only F02D41/0235)}
- F01B 7/02: with oppositely reciprocating pistons
- F01B 7/14: acting on different main shafts
- F02B 25/08: Engines with oppositely-moving reciprocating working pistons
- F02B 29/0412: {Multiple heat exchangers arranged in parallel or in series}
- F02B 33/44: Passages conducting the charge from the pump to the engine inlet, e.g. reservoirs
- F02B 37/04: Engines with exhaust drive and other drive of pumps, e.g. with exhaust-driven pump and mechanically-driven second pump
- F02B 75/02: Engines characterised by their cycles, e.g. six-stroke
- F02B 75/282: {the pistons having equal strokes}
- F02D 41/064: {at cold start (F02D41/067 takes precedence)}
- 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
- F02B 29/0418: {the intake air cooler having a bypass or multiple flow paths within the heat exchanger to vary the effective heat transfer surface}
- F02B 2075/025: {two}
- F02M 26/15: in relation to engine exhaust purifying apparatus
- F02M 26/23: Layout, e.g. schematics
- Y02T 10/12: Improving ICE efficiencies
- F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16)
- F01B: MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES (of rotary-piston or oscillating-piston type F01C; of non-positive-displacement type F01D; internal-combustion engines F02B; combustion-product engine plants F02G; machines or engines, other than of positive-displacement type, for liquids F03B; positive-displacement engines driven by liquids F03C; wind motors F03D; positive-displacement machines for liquids F04B; rotary-piston, or oscillating-piston, positive-displacement machines for liquids F04C)
- F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G)
- 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)
- F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

Exhaust temperature management strategies for an opposed-piston, two-stroke engine with EGR are based on control of a ratio of the mass of fresh air and external EGR delivered to a cylinder to the mass of the trapped charge (density of the delivered charge multiplied by the trapped volume at port closing).

## Claims

### Claim 1

A method of operating a two-stroke cycle, opposed-piston engine, the engine including at least one cylinder with exhaust and intake ports, a charge air subsystem to provide charge air to an intake port of the engine, and an exhaust subsystem to receive exhaust from at least one exhaust port of the engine, in which an exhaust gas recirculation (EGR) loop has a loop input coupled to the exhaust subsystem and a loop output coupled to the charge air subsystem, a supercharger is operable to pump charge air in the charge air subsystem, a backpressure device is operable to control backpressure in the exhaust subsystem, and the exhaust subsystem includes an after-treatment catalyst device, the method comprising:
generating exhaust gas in the at least one ported cylinder of the engine;
transporting the exhaust gas from an exhaust port of the at least one ported cylinder through the exhaust channel;
recirculating a portion of the exhaust gas from the exhaust subsystem;
mixing recirculated exhaust gas with fresh air to form charge air;
pressurizing the charge air;
providing the charge air through an intake port of the at least one ported cylinder;
applying backpressure to the exhaust subsystem; and,
trapping charge air and exhaust gas in the at least one ported cylinder in response to closure of the intake and exhaust ports such that an air delivery ratio (∧*) has a value in the range of 0.4≤∧*≤1.0, where Λ*=mdel/pdelVtr, mdel is the total mass of pressurized charge air (delivered charge) provided through the intake port, and ρdel′Vtr is the density of the delivered charge multiplied by a trapped volume of the at least one ported cylinder at closure of the exhaust and intake ports;
wherein trapping the charge air and exhaust gas causes a temperature of the trapped charge air and exhaust gas to increase to a light-off level for after-treatment catalysts in the exhaust subsystem.

### Claim 2 (depends on 1)

The method of claim 1, in which 0.4≤∧*≤1.5 for a cold start of the engine.

### Claim 3 (depends on 1)

The method of claim 1, in which 0.48≤∧*≤0.6 for a low load condition of the engine.

### Claim 4 (depends on 3)

The method of claim 3, wherein the after-treatment catalyst device includes a diesel oxidation catalyst device.

### Claim 5 (depends on 1)

The method of claim 1, in which 0.5≤∧*≤0.85 for a high load condition of the engine.

### Claim 6 (depends on 1)

The method of claim 1, in which 0.7≤∧*≤1.0 for a low speed condition of the engine.

### Claim 7 (depends on 1)

The method of claim 1, wherein the after-treatment catalyst device includes a diesel oxidation catalyst device.