FR2708668A1 - Device for charging (filling) a combustion engine - Google Patents

Abstract

Device for charging, or supercharging, with fresh gases and according to a cyclic pressure, a combustion engine of the 2-stroke type. This device consists mainly of a pump (1) with reciprocating movement driven by the engine through a connecting rod-crank system (3) or the equivalent and operating at the same speed (number of cycles per unit time) as the engine but the angular setting of which is advanced by approximately 90 DEG with respect to the cycle of the engine piston. This pump makes it possible to achieve, with very high efficiency, partial scavenging of the engine cylinder, under low pressure, then complementary filling under increasing pressure. It is particularly suitable, as a double pump, for charging (filling) a pair of cylinders of a 2-stroke engine.

Description

DEVICE FOR SUPPLYING AN EXPLOSION ENGINE
The present invention relates to a device for supplying or supercharging new gas to an internal combustion engine. Without prejudice to other possible applications (4-stroke engine ...), it is particularly suitable for the tsur) 2-stroke engine power supply, with intake ports with independent control from that of the exhaust ports, (to positive ignition or diesel type, carburetor or petrol injection.)
The device according to the invention allows the engine to operate on an optimized cycle, without adding oil to the fuel, and to obtain performance in terms of power, driving torque, fuel consumption and cleanliness Cantipollution) better than those of the engines. 4-stroke supercharged or not, while retaining the advantages of the 2-stroke engine: simpler, compact, less knives
The 2-stroke engine, compared to the 4-stroke engine, has a theoretically "specific power" (power per unit volume of displacement) because it has one engine time in two instead of one in four. However, in practice, the performance of the traditional 2-stroke engine is penalized by the fact that the filling with new gas of the cylinder is done under poorly controlled conditions, which leads to
- a specific power not double but about 1.5 times that of the 4-stroke engine
- a higher "specific consumption (consumption per unit of power)
- loss of new gas fueled by the exhaust
In addition, the traditional 2-stroke engine requires the addition of oil to the fuel to lubricate the crankcase / crankshaft (used as a pump for supplying new gas), increasing its pollution. The pump integrated in the engine has an imposed displacement (equal to that of the engine) and an imposed setting (cycle shifted by 1800 from the engine cycle) which does not allow optimizing the adjustment of the sweeping of the gases burned by the new gases, or of the possible additional filling (after closing the orifices d '' exhaust)
The addition of a supercharging by compressor (driven by the engine or by a turbine powered by the burnt gases) generating a constant pressure inside the engine cycle, does not make it possible to separately dose the sweep and any additional filling. Turbocharging does not work at low engine speeds and has a response time when starting. Energy is drawn with a poor efficiency (in the turbine)
It follows from all of this that the traditional 2-stroke engine is reserved for limited applications (in particular the motorization of small vehicles with 2 wheels).

 The device according to the invention overcomes these drawbacks. It is a volumetric supply at cyclic pressure (variable inside the engine cycle), associated with a 2-stroke engine and allowing to optimize the sweeping and the additional filling.

It comprises, according to a first characteristic, a suction and precompression system for new gases, composed of
- a diaphragm or piston air pump R, driven directly, or through an appropriate device, by the engine crankshaft, operating at the same speed (number of cycles per unit of time), driven by an alternating movement like the engine piston but whose timing with respect to the engine cycle can be chosen (for example, in advance of 90) as well as its displacement (for example greater).

 - associated with a non-return valve on the pump supply, and with a capacity (volume) on the connection between the pump outlet and the engine intake.

This suction / precompression system is associated with an optimized definition of the engine cycle and intake / exhaust sequences, characterized by the following sequence
exhaust inlet 1. partial emptying, by closed setting open at atmospheric pressure 2. partial flushing, under open low pressure 3. additional filling, "closed under increasing pressure 4. complementary compression closed 5. explosion 6. expansion
The use of the device according to the invention, in combination with this optimized cycle, allows:
- to make the piston work (during the expansion of the burnt gases) over a greater stroke than that of the compression, to increase the efficiency and decrease the specific consumption
- to control and measure the sweeping and filling rates separately, without loss of new gases from the exhaust
- to control the energy consumed:
. the pressure generated is cyclic, variable throughout the cycle to adapt to the value just necessary to ensure the sweeping (low pressure) then the additional filling (increasing pressure), therefore with the minimum of energy loss during transfer
only the volume of energy consumed is taken
actually transferred. At low load, a large part
volume pre-compressed by the pump is not transferred, and remains
kills its energy in the next pump cycle.

Another advantage of the device according to the invention is the maintenance at low loads of a proportion of burnt gases mixed with new gases, thereby raising the temperature of the mixture and facilitating combustion, in particular cold, and providing several successive combustions of a portion. gases (antipollution).

A possible variant is to introduce a variable restriction at the inlet of the pump to modulate the quantity of new gases transferred into the engine.

Another possible variant is to introduce a capacity between the restriction and the non-return valve to improve the operation of the pump.

Another possible variant is to vary the angular setting of the pump according to the engine speed (increase at high speed the phase advance of the pump relative to the engine piston) to accommodate reduced transfer times and maintain optimum filling at high speed.

The proposed system is particularly interesting for the 2-stroke 2-cylinder engine, with double pump, which compared to the 4-stroke 4-cylinder engine, supercharged or not, is
- more compact
- lighter
- cheaper to produce
- same balancing of the crankshaft (same number of engine times per crankshaft revolution, that is to say 2)
- high specific power
- high available torque even at low speed, supercharged supply available at all times, with no response time
- reduced consumption, reinforced by
. better cold combustion,
. low thermal inertia,
therefore advantage in case of frequent starts.

- better pollution control (successive combustions)
The accompanying drawings illustrate an embodiment of the invention:
FIG. 1 represents in section the device according to the invention,
- Figure 2 shows the diagram of the motor and pump cycles.

 With reference to these drawings, the device comprises an air pump (1) with a membrane (2) driven by a connecting rod / crank device (3) driven directly by the engine crankshaft (4) or through a toothed belt (5) or an appropriate device. A non-return valve (6) is arranged at the inlet of the pump. The displacement V1 of the pump, the volume V2 of the capacity (7) interposed between the outlet of the pump and the inlet of the engine cylinder (8), and the timing of the pump with respect to the engine piston cycle (9) are chosen to optimize the supply of the displacement engine V3.

 A variable restriction (10) is interposed in front of the inlet valve of the pump, to create a variable pressure drop and modulate the quantity of new gases sucked in by the pump.

 A capacity (11) is interposed between the variable restriction (10) and the non-return valve (6) to optimize the operation of the pump. This restriction (10), capacity (11), non-return valve (6), pump (I) and capacity C7) assembly can be doubled to supply 2 engine cylinders.

 PHASE 1: Before arriving at the bottom dead center of the engine piston, the exhaust port opens, allowing the partial emptying of the burnt gases by atmospheric pressure.

 PHASE 2: Arriving at the bottom dead center of the engine piston, the intake opening opens, allowing the scavenging of the burnt gases, remaining in the engine cylinder (8), by the new gases.

The diaphragm (2) of the pump is at mid-stroke. The extent of the scanning depends on the opening of the restriction (10).

 PHASE 3: From a partial rise of the engine piston (9), the exhaust port closes.

The diaphragm (2) approaches its maximum stroke., And supplies increasing pressure to the engine cylinder (8) to complete its filling. The pressure in the cylinder (8) increases doubly due to the decrease in volume of gases in the cylinder (8) and due to the additional filling. The extent of the additional filling depends on the opening of the restriction 10).

 PHASE 4: About halfway through the engine piston (9), the intake opening closes.

The engine piston (9) continues to compress until top dead center
The pump begins its suction cycle, the non-return valve (6) opens when the pressure in the pump becomes lower than the pressure upstream of the valve.

 PHASE 5: Explosion of the gases in the engine cylinder (8).

 PHASE 6: Gas expansion in the engine cylinder (8), the pump ends its stroke in the suction direction. The non-return valve (6) closes when the pump reverses its movement to initiate the precompression of the gases.

Claims (6)

 - an air pump (1) with membrane (2), external to the crankshaft housing, driven by a connecting rod / crank device (3) driven directly by the engine crankshaft or through a toothed belt or an appropriate device, operating at the same speed (number of cycles per unit of time) that the engine moves with an alternating movement like the engine piston, but whose timing in relation to the engine cycle can be chosen (for example in advance of 90) as well as its displacement (for example larger).  1 Device for supplying or supercharging with new gas and according to a cyclic pressure (that is to say variable within the engine cycle), an internal combustion engine, in particular of the 2-stroke type and provided with intake orifices control independent of those of the exhaust orifices (positive ignition or of the diesel type, with carburetor or petrol injection ...) device characterized in that it comprises r  - associated with a non-return valve (6) on the pump supply and with a capacity (7) interposed on the link between the pump output and the motor supply, and, the volume V2 of which can be selected.  2. Device according to claim 1 characterized in that the pump diaphragm is replaced by a piston or a movable element delimiting a variable volume.  in the engine.  the amount of new gas drawn in by the pump and transferred  (10) at the inlet of the non-return valve and the pump to modulate  3. Device according to claim 1 or claim 2 2 characterized in that it comprises a variable restriction  4. Device according to any one of the preceding claims, characterized in that the angular setting of the pump with respect to the engine cycle is modulated as a function of the engine rotation speed.  5. Device according to any one of the preceding claims, characterized in that it comprises a capacity (11) between the variable restriction (10) and the non-return valve (6).  6. Device according to any one of the preceding claims, characterized in that it comprises a double pump, supplying a 2-stroke engine with 2 cylinders or a pair of 2-stroke engine cylinders comprising more than 2 cylinders.