# US 11,028,694 B2 · Valve train for opposed-piston four-stroke engine

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- Number: US 11,028,694 B2
- Document ID: US11028694B2
- Status: Granted
- Kind: B2
- Application number: 16/135,871
- Filed: 2018-09-19
- Published: 2019-03-28
- Granted: 2021-06-08
- Earliest claimed: 2017-09-27
- Assignees: AVL Powertrain Engineering, Inc.
- Applicants: AVL Powertrain Engineering, Inc.
- Inventors: Vasile Frasinel; Jennifer Weiche
- Web page: https://patentgrep.com/patent/US11028694B2

## CPC

- F01B 7/14: acting on different main shafts
- F01L 1/026: {Gear drive}
- F01L 1/047: Camshafts
- F01L 1/181: {Centre pivot rocking arms}
- F02B 75/282: {the pistons having equal strokes}
- F02F 1/004: {Cylinder liners (F02F1/08, F02F1/16 take precedence)}
- F02F 1/186: {for use in engines with two or more pistons reciprocating within same cylinder}
- F02F 1/22: characterised by having ports in cylinder wall for scavenging or charging
- F01L 2001/0537: {Double overhead camshafts [DOHC]}
- F01L 2001/054: {Camshafts in cylinder block}
- F01L 2305/00: Valve arrangements comprising rollers
- F01L 2820/01: Absolute values
- F01L 2820/02: Formulas
- 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)
- F01L: CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G)
- F02F: CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES

## Abstract

An opposed-piston engine includes an engine block, at least two intake valves, and at least two exhaust valves. The engine block includes a first center section and a second center section. The first center section defines a first cylinder half bore having a first longitudinal axis and a first open end. The second center section defines a second cylinder half bore having a second longitudinal axis and a second open end. The second longitudinal axis is offset from the first longitudinal axis. The first and second open ends overlap to form and opening therebetween that places the first and second cylinder half bores in fluid communication with one another to form a single cylinder. The intake valves are arranged at the first open end of the first cylinder half bore. The exhaust valves are arranged at the second open end of the second cylinder half bore.

## Claims

### Claim 1

An opposed-piston engine comprising:
an engine block including a first center section and a second center section, the first center section defining a first cylinder half bore having a first longitudinal axis and a first open end, the second center section defining a second cylinder half bore having a second longitudinal axis and a second open end, the second longitudinal axis of the second cylinder half bore being offset from the first longitudinal axis of the first cylinder half bore, the second open end of the second cylinder half bore overlapping the first open end of the first cylinder half bore to form an opening between the first and second cylinder half bores, the opening placing the first and second cylinder half bores in fluid communication with one another to form a single cylinder;
at least three intake valves having the same lift profile arranged at the first open end of the first cylinder half bore;
at least three exhaust valves having the same lift profile arranged at the second open end of the second cylinder half bore;
an intake camshaft that actuates the at least three intake valves;
an exhaust camshaft that actuates the at least three exhaust valves;
an intake rocker arm shaft;
first intake rocker arms pivotally mounted on the intake rocker arm shaft and configured to open first and second ones of the intake valves when the first intake rocker arms engage first lobes on the intake camshaft, the first and second intake valves located a first distance from the intake rocker arm shaft;
a second intake rocker arm pivotally mounted on the intake rocker arm shaft and configured to open a third one of the intake valves when the second intake rocker arm engages a second lobe on the intake camshaft, the third intake valve located a second distance from the intake rocker arm shaft that is different than the first distance;
an exhaust rocker arm shaft;
first exhaust rocker arms pivotally mounted on the exhaust rocker arm shaft and configured to open first and second ones of the exhaust valves when the first exhaust rocker arms engage first lobes on the exhaust camshaft, the first and second exhaust valves located a third distance from the exhaust rocker arm shaft; and
a second exhaust rocker arm pivotally mounted on the exhaust rocker arm shaft and configured to open a third one of the exhaust valves when the second exhaust rocker arm engages a second lobe on the exhaust camshaft, the third exhaust valve located a fourth distance from the exhaust rocker arm shaft that is different than the third distance.

### Claim 2 (depends on 1)

The opposed-piston engine of claim 1 wherein the size of each of the exhaust valves is equal to the size of each of the intake valves.

### Claim 3 (depends on 1)

The opposed-piston engine of claim 1 wherein:
the second distance is less than the first distance; and
the fourth distance is less than the third distance.

### Claim 4 (depends on 3)

The opposed-piston engine of claim 3 wherein:
each of the first intake rocker arms has a first length;
the second intake rocker arm has a second length that is less than the first length of each of the first intake rocker arms;
each of the first exhaust rocker arms has a third length; and
the second exhaust rocker arm has a fourth length that is less than the third length of each of the first exhaust rocker arms.

### Claim 5 (depends on 3)

The opposed-piston engine of claim 3 wherein:
each of the first lobes on the intake camshaft has a first height;
the second lobe on the intake camshaft has a second height that is greater than the first height;
each of the first lobes on the exhaust camshaft has a third height; and
the second lobe on the exhaust camshaft has a fourth height that is greater than the third height.

### Claim 6 (depends on 1)

The opposed-piston engine of claim 1 wherein:
the intake valves include stems that are oriented parallel to the first longitudinal axis of the first cylinder half bore; and
the exhaust valves include stems that are oriented parallel to the second longitudinal axis of the second cylinder half bore.

### Claim 7 (depends on 1)

The opposed-piston engine of claim 1 further comprising:
a first fuel injector positioned at or near the first longitudinal axis of the first cylinder half bore, wherein the intake valves are positioned around the first fuel injector along an outer perimeter of the first cylinder half bore; and
a second fuel injector positioned at or near the first longitudinal axis of the second cylinder half bore, wherein the exhaust valves are positioned around the second fuel injector along an outer perimeter of the second cylinder half bore.

### Claim 8 (depends on 1)

The opposed-piston engine of claim 1 wherein the first and second center sections are formed separate from one another.

### Claim 9

An opposed-piston engine comprising:
an engine block including a first center section and a second center section, the first center section defining a first cylinder half bore having a first longitudinal axis and a first open end, the second center section defining a second cylinder half bore having a second longitudinal axis and a second open end, the second longitudinal axis of the second cylinder half bore being offset from the first longitudinal axis of the first cylinder half bore, the second open end of the second cylinder half bore overlapping the first open end of the first cylinder half bore to form an opening between the first and second cylinder half bores, the opening placing the first and second cylinder half bores in fluid communication with one another to form a single cylinder;
a plurality of intake valves arranged at the first open end of the first cylinder half bore and configured to control the flow of intake air into the cylinder;
a plurality of exhaust valves arranged at the second open end of the second cylinder half and configured to control the flow of exhaust gas out of the cylinder;
an intake rocker arm shaft;
first intake rocker arms pivotally mounted on the intake rocker arm shaft and configured to open first and second ones of the intake valves, the first and second intake valves located a first distance from the intake rocker arm shaft;
a second intake rocker arm pivotally mounted on the intake rocker arm shaft and configured to open a third one of the intake valves, the third intake valve located a second distance from the intake rocker arm shaft that is different than the first distance;
an exhaust rocker arm shaft;
first exhaust rocker arms pivotally mounted on the exhaust rocker arm shaft and configured to open first and second ones of the exhaust valves, the first and second exhaust valves located a third distance from the exhaust rocker arm shaft; and
a second exhaust rocker arm pivotally mounted on the exhaust rocker arm shaft and configured to open a third one of the exhaust valves, the third exhaust valve located a fourth distance from the exhaust rocker arm shaft that is different than the third distance.

### Claim 10 (depends on 9)

The opposed-piston engine of claim 9 wherein the plurality of intake valves includes three intake valves and the plurality of exhaust valves includes three exhaust valves.

### Claim 11 (depends on 9)

The opposed-piston engine of claim 9 wherein the size of each of the exhaust valves is equal to the size of each of the intake valves.

### Claim 12 (depends on 9)

The opposed-piston engine of claim 9 further comprising:
a single intake camshaft that actuates all of the intake valves; and
a single exhaust camshaft that actuates all of the exhaust valves.