# US 8,783,222 B2 · Apparatus and method of control of balance shafts in an engine

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- Number: US 8,783,222 B2
- Document ID: US8783222B2
- Status: Granted
- Kind: B2
- Application number: 13/981,496
- Filed: 2012-01-19
- Published: 2013-11-28
- Granted: 2014-07-22
- Earliest claimed: 2011-02-15
- Assignees: RENAULT s.a.s.
- Applicants: Alexandre Anton; Jean-Yves Der-Matheossian
- Inventors: Alexandre Anton; Jean-Yves Der-Matheossian
- Web page: https://patentgrep.com/patent/US8783222B2

## CPC

- F16F 15/264: {Rotating balancer shafts (F16F15/262 takes precedence)}
- F01L 1/344: changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
- F16C 3/20: Shape of crankshafts or eccentric-shafts having regard to balancing
- F16F 15/265: {Arrangement of two or more balancer shafts (F16F15/267 takes precedence)}
- Y10T 74/1836: Rotary to rotary
- F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F01L: CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

An internal combustion engine including: an even number of inline cylinders, each accommodating a piston; a crankshaft rotatably mounted about an axis; first and second balance shafts rotatably mounted about balancing axes parallel to and separate from the engine axis; and first and second mechanisms for rotating the first and second balance shafts at rotating speeds that are dependent on a rotating speed of the crankshaft. The balancing axes of the first and second balance shafts coincide, and the second rotating mechanism adjusts a phase difference between angular positions of the first and second balance shafts around the balancing axis.

## Claims

### Claim 1

An internal combustion engine comprising:
an even number of in-line cylinders;
a crankshaft mounted to rotate about an engine axis;
first and second balance shafts mounted to rotate about balance axes that are parallel and distinct from the engine axis;
first rotational-drive means for turning the first balance shaft in a direction of rotation that is opposite the direction of rotation of the crankshaft and at a rotational speed that is a function of a rotational speed of the crankshaft;
second rotational-drive means for turning the second balance shaft in a direction of rotation that is opposite the direction of rotation of the first balance shaft and at a rotational speed that is a function of the rotational speed of the crankshaft; and
phase adjustment means for adjusting a phase angle between the first and second balance shafts.

### Claim 2 (depends on 1)

The internal combustion engine as claimed in claim 1, in which the first and second rotational-drive means are configured to drive the first and second balance shafts at equal rotational speeds when the phase adjustment means is inactive.

### Claim 3 (depends on 1)

The internal combustion engine as claimed in claim 1, in which:
the second rotational-drive means comprises a reducer and an epicyclic gear train; and
the phase adjustment means is configured to control a reduction ratio of the epicyclic gear train.

### Claim 4 (depends on 3)

The internal combustion engine as claimed in claim 3, in which:
the epicyclic gear train comprises an outer annulus, a sun gear, and a planet carrier carrying at least one planet pinion interposed between the outer annulus and the sun gear; and
the phase adjustment means comprises an electric motor including an output shaft connected to the planet carrier to adjust the angular position of each planet pinion about an axis of the outer annulus.

### Claim 5 (depends on 4)

The internal combustion engine as claimed in claim 4, in which:
one of the first and second balance shafts is fixed or directly connected to the outer annulus or to the sun gear; and
the other of the first and second balance shafts is indirectly connected to the outer annulus or to the sun gear, via the reducer.

### Claim 6 (depends on 4)

The internal combustion engine as claimed in claim 4, in which:
one of the first and second balance shafts is formed as one with the outer annulus or the sun gear; and
the other of the first and second balance shafts is indirectly connected to the outer annulus or to the sun gear via the reducer.

### Claim 7 (depends on 1)

The internal combustion engine as claimed in claim 1, in which the first and second balance shafts each comprise a balance weight configured to generate a centrifugal force of an intensity equal to that generated by the other balance weight when the first and second balance shafts are rotating at a same angular velocity.

### Claim 8 (depends on 7)

The internal combustion engine as claimed in claim 7, in which, with each cylinder housing a piston, the balance weight of one of the balance shafts is at bottom dead center when the pistons of two central cylinders are at top dead center.

### Claim 9 (depends on 7)

The internal combustion engine as claimed in claim 7, in which a median plane between planes of rotation of centers of gravity of the balance weights coincides with a plane of symmetry of two central cylinders.

### Claim 10 (depends on 1)

The internal combustion engine as claimed in claim 1, in which the balancing axes of the first and second balance shafts are separate.

### Claim 11 (depends on 1)

The internal combustion engine as claimed in claim 1, in which the balancing axes of the first and second balance shafts coincide.

### Claim 12 (depends on 1)

The internal combustion engine as claimed in claim 1, in which one of the first and second balance shafts is hollow and has the other of the first and second balance shafts passing through it.

### Claim 13 (depends on 1)

The internal combustion engine as claimed in claim 1, further comprising a cylinder block covered by a cylinder head, in which the first and second balance shafts are at least partially housed inside the cylinder head.

### Claim 14 (depends on 1)

The internal combustion engine as claimed in claim 1, in which, with each cylinder housing a piston, the phase adjustment means comprises:
acquisition means for acquiring the rotational speed of the crankshaft;
acquisition means for acquiring a phase angle that is a difference in phase between angular positions of the first and second balance shafts when the pistons housed in two central cylinders are at top dead center; and
control means for controlling the phase adjustment means as a function of the acquired rotational speed and of the acquired phase angle.

### Claim 15 (depends on 1)

The internal combustion engine as claimed in claim 1, in which when the phase adjustment means is inactive, the first and second rotational-drive means are configured to drive the first and second balance shafts at rotational speeds equal to that of the crankshaft if the engine has two cylinders and equal to twice that of the crankshaft if the engine has four cylinders.

### Claim 16 (depends on 1)

A method for controlling an internal combustion engine as claimed in claim 1, comprising:
acquiring the rotational speed of the crankshaft;
acquiring a phase angle that is a difference in phase between the angular positions of the first and second balance shafts when the pistons housed in two central cylinders are at top dead center; and
when the acquired rotational speed exceeds a first determined threshold, controlling the phase adjustment means to set the phase angle to a predetermined angle less than 90°; and
when the acquired rotational speed drops below a second determined threshold, controlling the phase adjustment means to set the phase angle to 180°.

### Claim 17 (depends on 16)

The control method as claimed in claim 16 for controlling an internal combustion engine, in which the predetermined angle is equal to twice an angle of inclination between a plane passing through axes of two central cylinders and a plane passing through an engine axis and through a median axis between the two balancing axes.