GB2071210A

GB2071210A - Four-stroke engine with a charging piston pump

Info

Publication number: GB2071210A
Application number: GB8106370A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-02-29
Filing date: 1981-02-27
Publication date: 1981-09-16
Also published as: FR2477224A1; DE3007746A1

Abstract

An air or mixture charging cylinder 10 is disposed between the working cylinders 2, 3 which receive a charge alternately from the charging cylinder. The cylinder 10 is supplied from a pipe 19 containing a throttle valve 26 via two inlet valves 18a, 18b. <IMAGE>

Description

SPECIFICATION A fuel-burning engine This invention relates to fluid fuel-burning engines of the kind which comprise at least two working cylinders, arranged to operate in a fourstroke cycle, an inlet, an outlet valve, and a device for supercharging the working cylinders with a mixture of fluid fuel and air.

In order to increase their power output, some fuel-burning engines have various known forms of supercharging devices for increasing the power derived from the working cylinders. Such known devices are usually turbo-superchargers, in which a turbine wheel in the intake system of the engine is driven by a second turbine wheel in its exhaust system and scoops additional air into the cylinders, thus increasing the volumetric efficiency of the fuel/air mixture and developing more power per working piston stroke. Turbo-supercharging devices of this kind are effective and advantageous only at high speeds and they involve the use of expensive apparatus which is susceptible to malfunction.

An object of the present invention is to construct a fuel-burning engine, and particularly an internal-combustion engine, comprising a supercharging device which can considerably increase the power output of the engine in a simple manner, without being sensitive to breakdown, and without the need for additional units for supercharging. Accordingly, the present invention provides a fluid fuel-burning engine of the kind set forth, wherein said two working cylinders are associated with a supercharging cylinder in a two-stroke cycle and a bypass extends from the supercharging cylinder to each working cylinder, and wherein a crank pin corresponding to the supercharging cylinder is offset by 1800 around the axis of rotation of a crankshaft relative to crank pins which correspond to the two working cylinders.

The aforementioned construction results in an internal-combustion engine which incorporates a supercharger. Power can be increased, more particularly at lower speeds, in contrast to, for example, exhaust-driven supercharging. A fluid fuel-burning engine constructed in accordance with the invention ensures an automatic increase in the volumetric efficiency of the working cylinders and in the loaded weight, resulting in a power increase over substantially the entire speed range. Since the supercharging device according to the invention is built into the engine, there is no need for additional wires, tubes, pressure containers, fittings, drive elements or the like. The overall result is a compact supercharged drive unit which can be made and sold at reasonable cost.

Since the supercharging device operates in a twostroke cycle and the pistons of the working cylinders and the piston of the supercharging cylinder are constantly in opposition to one another, the supercharging process can be exactly controlled.

The supercharging piston serves each working cylinder alternately, thus corresponding to the working rhythm of the engine. The supercharging device which is incorporated in accordance with the invention is advantageous in an optimum manner. The intake volume of the supercharging cylinder can easily be adapted to the required conditions. It can, for example, be one-and-a-half to twice the volume of each working cylinder. The device is equally applicable to spark-ignition and diesel engines.

Advantageously, the supercharging cylinder and its associated crank pin are disposed between the working cylinders and their crank pins.

Bypasses lead from the supercharging cylinder to inlet valves of the working cylinders and each valve, when opened, furnishes a passage for the fuel/air mixture (or air to be compressed in the case of diesel engines) through the appropriate working cylinder.

According to another feature of the invention, a throttle device, such as a throttle valve, can be disposed in an intake pipe of the supercharging cylinder. By this means, the power output can be adapted to varying load requirements, as in the use of the engine as a vehicle engine. The throttle valve is arranged controllably to reduce or increase the inlet cross-section of the intake pipe.

This method of regulating the inlet cross-section can simultaneously be used to vary the volumetric efficiency at the supercharging region. A vehicle engine constructed in the aforementioned manner is most effective in conserving fuel without the need of a "fifth stroke" and switchable cylinder units. An engine in accordance with the invention is thus a simple but very economic engine.

The supercharging cylinder, which has a larger diameter than each working cylinder, can have more than one inlet valve, in order to obtain maximum inlet cross-sections and thus reduce flow losses. The valves will be opened and closed simultaneously with such an arrangement.

Advantageousiy, a fuel-burning engine in accordance with the invention is a two-cylinder inline engine or an opposed four-cylinder-type engine. A simple method is accordingly provided for obtaining a considerable power increase with high torque and high sealing-tightness. The power increase can be 50% of more as compared with a similar engine not having the features of this invention.

The invention will now be described with reference to an embodiment shown in the single accompanying drawing, which drawing is a diagrammatic cross-section throug a two-cylinder in-line engine in accordance with the invention.

Reference to the accompanying drawing, that drawing shows a two-cylinder four-stroke engine 1 fitted with the supercharging device. The engine has working cylinders 2, 3 respectively provided with an inlet valve 4, 5, and outlet valve 6, 7 and an outlet pipe 8, 9. A cylinder 10 for a supercharging piston 11 is disposed between the working cylinders 2 and 3. A common crankshaft 12 is rotatably mounted in bearings 1 7 and is constructed so that the crank pin 13 for actuating the supercharging piston 11 is offset by 1800 around the axis of rotation of that crankshaft relative to the crank pins 14, 1 5 for pistons 2a, 3a of the cylinders 2 and 3. The rods connecting all of the pistons 2a, 3a and 11 to the crank pins are each denoted by 16.The crank pin 13 for the piston 11 is offset relative to the crank pins 14, 1 5 for the pistons 2a, 3a for the purpose of optimum mass equilibrium of the crankshaft 12. The cylinder 10 for the supercharging piston 11 has at least one inlet valve. In the illustrated example, inlet valves 1 8a and 1 8b are connected to a common intake pipe 19. The valves 1 8a and 1 8b are opened and closed simultaneously. All the valves are actuated by closure springs 20 controlled by a camshaft (not shown). The valves are disposed in a cylinder head 21 secured in a conventional manner to an engine housing 22. An oil sump 23 is disposed in a conventional manner under the crankshaft 12.Instead of the illustrated poppet valves, rotary slide valves or diaphragms can control the inlet.

Bypasses 24, 25 extend from the supercharging cylinder 10 to the inlet valves 4, 5 of the working cylinders 2 and 3. Each valve 4, 5, when opened, allows the mixture to flow into the corresponding working cylinder. The working cylinders, which are controlled in a four-stroke cycle, co-operate with the supercharging device 10,11 18a,18b in a two-stroke cycle, in which the working-cylinder pistons 2a, 3a always run in opposition to the piston 11 of the supercharging cylinder, thus ensuring that the supercharging process is exactly controlled. The supercharging piston 11 thus alternately serves the left and the right (as seen in the drawing) working cylinders in a rhythm corresponding to the strokes of the working cylinders, which follow one another in operation in a four-stroke cycle.

In the case of the illustrated internal combustion engine, which has an incorporated supercharger and which can deliver a variable power at a uniform speed, it is particularly advantageous to disposed a throttle valve 26 in the intake pipe 1 9 and to arrange it to be actuated around a shaft 27. By this method, the engine power can be adapted to changes in load, as in a vehicle engine. The throttle valve 26 is arranged to reduce or increase the inlet cross-section of the intake pipe 1 9. If the inlet cross-section is regulated in the aforementioned manner, the volumetric efficiency at the supercharging region is simultaneously varied. About a third of the power of the supercharged engine is available for the aforementioned adjustment. In order to supply the power required at each moment, the throttle valve may advantageously be controlled by a computer system. Engines of this kind are preferably equipped with a variable-jet carburettor, which supplies the right amount of fuel for each required quantity of air, thus continuously obtaining an optimum mixture.

The compact, sturdy design results in a rugged fuel-burning engine for spark-ignition or diesel operation, the engine having a highly efficient supercharging system.

Claims

1. A fluid fuel-burning engine of the kind set forth, wherein said two working cylinders are associated with a supercharging cylinder in a two stroke cycle and a bypass extends from the supercharging cylinder to each working cylinder, and wherein a crank pin corresponding tq the supercharging cylinder is offset by 1 800 around the axis of rotation of a crankshaft relative to crank pins which correspond to the two working cylinders.

2. An engine as claimed in claim 1, wherein the supercharging cylinder and the associated crank pin are disposed between the working cylinders and their crank pins, and wherein each bypass extends from the supercharging cylinder to an inlet valve of the corresponding working cylinder, each working cylinder being alternately served by the supercharging piston when the engine is in operation.

3. An engine as claimed in claim 1 or 2, wherein throttle valve or other throttle device is disposed in an intake pipe of the supercharging cylinder.

4. An engine as claimed in any preceding claim, wherein the diameter of the supercharging cylinder is greater than the diameter of each working cylinder.

5. An engine as claimed in any preceding claims, wherein the intake volume of the supercharging cylinder is between substantially one-and-a-half and wice the volume of one of the working cylinders.

6. An engine as claimed in any preceding claim, wherein the supercharging cylinder has more than one inlet valve and the inlet valves are simultaneously opened and closed when the engine is in operation.

7. An engine as claimed in any preceding claim, wherein the engine is constructed as a two working-cylinder in-line engine.

8. An engine as claimed in any one of claims 1 to 6, wherein the engine is constructed as an opposed four-working-cylinder-type engine.

9 An engine as claimed in any one of claims 1 to 8, wherein the engine is a carburettor or diesel engine.

10. A fluid fuel-burning engine of the kind set forth, substantially as hereinbefore described with reference to the single Figure of the accompanying drawings.