# US 5,341,771 A · Internal combustion engine with variable combustion chambers and increased expansion cycle

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- Number: US 5,341,771 A
- Document ID: US5341771A
- Status: Granted
- Kind: A
- Application number: 07/800,920
- Filed: 1991-12-03
- Granted: 1994-08-30
- Earliest claimed: 1991-12-03
- Assignees: Motive Holdings Limited
- Inventors: Michael B. Riley
- Web page: https://patentgrep.com/patent/US5341771A

## CPC

- F02D 13/0234: {changing the valve timing only}
- F02B 41/04: in main cylinders
- F02D 13/0207: {changing valve lift or valve lift and timing}
- F02D 13/0269: {Controlling the valves to perform a Miller-Atkinson cycle}
- F02D 13/028: {for two-stroke engines}
- F02D 15/04: by alteration of volume of compression space without changing piston stroke
- F02F 1/4214: {specially adapted for four or more valves per cylinder}
- F02B 1/04: with fuel-air mixture admission into cylinder
- F02B 3/06: with compression ignition (compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02)
- F02B 2075/025: {two}
- F02B 2275/18: DOHC [Double overhead camshaft]
- Y02T 10/12: Improving ICE efficiencies
- 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)
- F02F: CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

An internal combustion engine and method for operating the same wherein the combustion chamber volume can be varied depending on throttle position by a member that is inserted into the combustion chamber, and wherein the intake valve is closed before the piston completes its intake stroke so that the expansion stroke is effectively lengthened. In the case of a two-stroke engine, some of the intake gas is expelled before combustion to achieve an effective lengthening of the expansion stroke.

## Claims

### Claim 1

An assembly for varying the combustion chamber volume in an internal combustion engine, comprising a housing with a chamber in communication with the combustion chamber; a piston slidably and adjustably extending into the housing chamber to adjust the volume of the combustion chamber; a hydraulic chamber containing hydraulic fluid, substantially enclosed by the piston and the housing on the opposite side of the piston from the combustion chamber, the hydraulic chamber having a hydraulic fluid channel extending from inside the hydraulic chamber to outside the hydraulic chamber to allow limited release of hydraulic fluid therethrough upon an increase in the pressure in the hydraulic fluid, and a hydraulic fluid port from inside the hydraulic chamber to outside the hydraulic chamber, the hydraulic port having an operable valve to open and close it and being sized substantially larger than the hydraulic fluid channel to allow a flow rate substantially greater than the flow rate through the hydraulic flow channel.

### Claim 2 (depends on 1)

The assembly of claim 1, wherein the hydraulic chamber further includes a hydraulic fluid inlet from outside the hydraulic chamber to inside the hydraulic chamber, the hydraulic fluid inlet being sized substantially larger than the hydraulic fluid channel to allow a flow rate substantially greater than the flow rate through the hydraulic fluid channel.

### Claim 3 (depends on 2)

The assembly of claim 2, wherein the hydraulic fluid inlet has a one-way valve positioned therein so that hydraulic fluid can flow only into the hydraulic chamber through the inlet.

### Claim 4

An assembly for varying the combustion chamber volume in an internal combustion engine, comprising a housing with a chamber in communication with the combustion chamber; a piston slidably and adjustably extending into the housing to adjust the volume of the combustion chamber; a screw extending through the housing, the longitudinal axis of the screw being parallel to the sliding axis of the piston; screw drive means; means to connect the screw to the piston; and a hydraulic chamber containing hydraulic fluid substantially enclosed by the piston and the housing on the opposite side of the piston from the combustion chamber to lessen the force of the piston on the screw upon combustion in the combustion chamber.

### Claim 5 (depends on 4)

The assembly of claim 4, wherein the screw drive means includes geared wheel on the screw.

### Claim 6 (depends on 4)

The assembly of claim 4, wherein the connect means includes a spring between the screw and the piston to absorb part of the combustion pressure on the piston.

### Claim 7 (depends on 4)

The assembly of claim 4, further comprising limiting means for limiting the slide of the piston in the housing.

### Claim 8 (depends on 7)

The assembly of claim 7, wherein the limiting means includes a closure on the hydraulic chamber side of the piston to mate with and close the hydraulic fluid channel when the piston is slid a predetermined distance into the hydraulic chamber.

### Claim 9 (depends on 8)

The assembly of claim 8, wherein the hydraulic fluid channel is in a wall of the housing opposite the piston, and the closure includes a plug to mate with the channel that is positioned outside the channel and urged toward the piston by a spring.

### Claim 10 (depends on 7)

The assembly of claim 7, wherein said limiting means includes a land in the housing wherein the housing on the piston side of the hydraulic chamber extends in the direction radial from the axis of piston travel a first distance and a second distance, the first distance being greater than the second distance, and the first distance and second distance having a land between them to stop the piston from travelling past the land toward the hydraulic chamber wall opposite the piston.

### Claim 11 (depends on 7)

The assembly of claim 7, wherein the limiting means includes means for limiting the slide of the piston away from the hydraulic chamber and into the combustion chamber.

### Claim 12 (depends on 11)

The assembly of claim 11, wherein said means for limiting the slide of the piston away from the hydraulic chamber and into the combustion chamber includes a stop on the housing on the combustion chamber side of the piston extending from the housing into the path of travel of the piston.

### Claim 13 (depends on 12)

The assembly of claim 12, wherein said stop is a ring.

### Claim 14

An assembly for varying the combustion chamber volume in an internal combustion engine, comprising a housing with a chamber in communication with the combustion chamber, a piston slidably and adjustably extending into the housing to adjust the volume of the combustion chamber; a hydraulic chamber containing hydraulic fluid, substantially enclosed by the piston and the housing on the opposite side of the piston from the combustion chamber, the hydraulic chamber having a hydraulic fluid channel extending from inside the hydraulic chamber to outside the hydraulic chamber to allow limited release of hydraulic fluid therethrough upon an increase in the pressure in the hydraulic fluid; and means for limiting the skew of the piston including a perforated hollow rod, one end of which is attached to the hydraulic chamber side of the piston and the other end of which is slidably mounted in the housing wall opposite the piston.

### Claim 15

A four-stroke internal combustion engine, comprising a cylinder; a working piston reciprocally mounted in the cylinder; a set of valves to control gas flow into and out of the cylinder, including an intake valve; means for operating the valves in timing with the reciprocation of the piston, whereby compressed gas in a combustion volume in the cylinder is ignited and expands to drive the piston through a power stroke and is then exhausted to outside the cylinder, and whereby the intake valve is closed before the piston completes the intake stroke; and means to vary the combustion volume by the insertion of a member into the cylinder.

### Claim 16 (depends on 15)

The engine of claim 15, wherein the volume-varying means is a volume varying piston slidably mounted in the cylinder in communication with the combustion volume.

### Claim 17 (depends on 15)

The engine of claim 15, wherein the gas entering the cylinder includes gaseous fuel, and further comprising a throttle in communication with the cylinder to adjust the amount of fuel entering the cylinder.

### Claim 18 (depends on 17)

The engine of claim 17 wherein the means to vary the combustion volume by the insertion of a member into the cylinder operates to decrease the combustion volume at low throttle and to increase the combustion volume at high throttle.

### Claim 19 (depends on 17)

The engine of claim 17, wherein the intake valve is closed before the piston completes the intake stroke at all throttle positions.

### Claim 20 (depends on 19)

The engine of claim 19, wherein the intake valve timing is fixed.

### Claim 21

A two-stroke internal combustion engine, comprising a cylinder; a set of at least one of valves and parts to control gas flow into and out of the cylinder; means for operating the at least one of valves and parts in timing with the reciprocation of the piston, whereby compressed gas in a combustion volume in the cylinder is ignited and expands to drive the piston through a power stroke and is then exhausted to outside the cylinder, and whereby some the intake gas in expelled prior to combustion; and means to vary the combustion volume by the insertion of a member into the cylinder.

### Claim 22 (depends on 21)

The engine of claim 21, wherein the valves include a bleed valve to allow the escape of same of the gas from the cylinder prior to combustion.

### Claim 23 (depends on 22)

The engine of claim 22, wherein the bleed valve bleeds gas from the cylinder to the compression chamber or intake manifold.

### Claim 24

A method of operating a four-stroke internal combustion engine having a cylinder, a working piston reciprocally mounted in the cylinder, a set of valves to control gas flow into and out of the cylinder, and means for operating the valves in timing with the reciprocation of the piston whereby gas is compressed by the piston to a combustion volume and is ignited and expands to drive the piston through a power stroke and is then exhausted to outside the cylinder, the method comprising closing the intake valves before the piston reaches the bottom of the intake stroke; and adjusting the combustion volume based on the throttle position of the engine, whereby the combustion volume is reduced for low throttle.

### Claim 25 (depends on 24)

The method of claim 24, wherein said step of adjusting of the combustion chamber volume includes adjustably inserting a member into the combustion chamber.

### Claim 26 (depends on 5)

The method of claim 5, wherein said member is volume adjusting piston slidably mounted in a housing attached to the cylinder, the volume adjusting piston and housing enclosed a hydraulic fluid chamber to cushion the pressure exerted on the volume adjusting piston by the combustion of gases in the cylinder.

### Claim 27 (depends on 26)

The method of claim 26, further comprising controllably allowing hydraulic fluid to be expelled from the hydraulic fluid chamber upon the exertion of pressure on the volume-adjusting piston by the combustion of gases in the cylinder, and controllably replacing said expelled hydraulic fluid upon the termination of such combustion pressure.

### Claim 28 (depends on 27)

The method of claim 27 wherein said controlling of expulsion and replacement of hydraulic fluid includes the use of a bleed channel from the hydraulic chamber to outside the hydraulic chamber for hydraulic fluid to pass through.

### Claim 29 (depends on 28)

The method of claim 28, wherein the adjustment of said volume adjusting piston is by turning a screw one end of which is attached to the piston and the other end of which is threaded through the housing.

### Claim 30 (depends on 29)

The method of claim 29, further comprising absorbing a portion of the combustion pressure on the volume-adjusting piston with a spring between the screw and the piston.

### Claim 31 (depends on 28)

The method of claim 28, further comprising abruptly draining the hydraulic chamber to accommodate abrupt withdrawal of the volume-adjusting piston into the hydraulic chamber, by opening a hydraulic fluid port having a size substantially larger than the size of the hydraulic fluid bleed channel to allow the passage of hydraulic fluid therethrough substantially faster than through the hydraulic fluid bleed channel.

### Claim 32

A method of operating a two-stroke internal combustion engine having a cylinder, a working piston reciprocally mounted in the cylinder, a set of valves to control gas flow into and out of the cylinder, and means for operating the valves in timing with the reciprocation of the piston whereby gas is compressed by the piston to a combustion volume and is ignited and expands to drive the piston through a power stroke and is then exhausted to outside the cylinder, the method comprising expelling a portion of the intake gas prior to combustion; and adjusting the combustion volume based on the throttle position of the engine whereby the combustion volume is reduced for low throttle.

### Claim 33 (depends on 32)

The method of claim 32, wherein the expulsion of intake gas is through a bleed valve from the cylinder to the intake manifold or compression chamber.