RU2449147C1 - Internal combustion engine - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: in an inlet pipeline, at a small distance to an inlet valve of a cylinder there is a blowdown valve installed driven from a common cam shaft. In the end of an inlet stroke, 40-50° to the top dead centre (TDC), the inlet valve is opened. Spent gases go through the open inlet valve and reach the closed blowdown valve. Near the TDC, with remaining 10°, the blowdown valve is opened, and the combustion chamber is blown with air from an inlet header, afterwards the cylinder filling starts. Such solution makes it possible to substantially expand the angle of valves closure, this increasing the filling phase.

EFFECT: higher specific capacity of the engine with preservation of low toxicity of spent gases.

4 cl, 5 dwg

Description

The invention relates to mechanical engineering, more specifically to reciprocating internal combustion engines.

In the text and in the illustrations (Fig. 1 ... Fig. 6) the following abbreviations are adopted:

- ICE - internal combustion engine,

- M _max - the maximum moment of the internal combustion engine,

- P _max - the maximum power of the internal combustion engine,

- TDC - top dead center of the piston,

- BDC - the bottom dead center of the piston,

- KS - combustion chamber,

- V _C - the volume of the cylinder,

- P _C - pressure in the cylinder, atm.

- V _cc - volume of the combustion chamber,

- exhaust gas - residual gases (exhaust gases),

- P _og - pressure of residual gases, atm.

- RP - purge receiver,

- V _RP - purge receiver volume, atm.

- P _RP - pressure in the receiver purge,

- KP - purge valve,

- VPC - intake valve

- OFF - exhaust valve.

On the pie charts of the valve timing:

- the opening or closing angle of the valves is counted clockwise, starting from the TDC of the beginning of the intake stroke in degrees of rotation of the crankshaft,

- thick lines correspond to the closed state of the valves,

- φ are the angles between the moments of opening or closing of the valves,

- α are the angles between TDC and BDC and the moments of valve opening,

- β are the angles between TDC and BDC and the moments of valve closure.

In the illustrations:

- Figure 1 - classic piston four-stroke internal combustion engine,

- Figure 2 is a pie chart of the gas distribution phases of the internal combustion engine in Figure 1,

- Figure 3 - ICE with forced blowing,

- Figure 4 is a pie chart of the timing of the internal combustion engine in Figure 3,

- Figure 5 - ICE with a controlled purge valve,

- Fig.6 is a pie chart of the timing of the internal combustion engine in Fig.5.

Features of the operation of various types of internal combustion engines are considered on the example of a single-cylinder gasoline internal combustion engine and injector power system.

Classic ICE, despite a number of shortcomings, is still widely used in transport and industry.

Such an internal combustion engine (see Figure 1) generally contains a cylinder 1 with a piston 2, VPK 3, VOK 4. The valves are driven by cams 5 of the camshaft 6. A piston 2 rotates the crankshaft through the connecting rod 7. The throttle, fuel injector and spark plug conditionally not shown.

Figure 2 presents a diagram of the valve timing.

ICE is shown at the end of the exhaust stroke, the piston almost reaches the TDC.

At low and idle speeds, the exhaust of such an engine has high toxicity (high levels of CO, CH). This is due to the fact that at the end of the exhaust stroke the exhaust gas inertia on the upward movement of the piston is small and they remain largely in the combustion chamber. In subsequent intake strokes, the exhaust gases are mixed with a fresh charge and make it difficult to burn.

There is a time when the pressure to reduce the toxicity of the exhaust end of the exhaust stroke as a seek from the inlet conduit may be better to blow air toward the COP of 3 to OFF MIC 4. The fact that near TDC during valve overlap (angle φ ₃₄₎ in the inlet pipe is larger than in the outlet, at this time the most intensive purge occurs.

The purge efficiency is different at different speeds and at different ICE loads. Good purge is obtained only in a small rev range (1500-3000 1 / min), therefore, empirically determined average values of the valve timing angles are set on a conventional ICE - α ₃ , α ₄ , β ₃ , β ₄ , φ ₃₄ , etc.

With an increase in the speed of the internal combustion engine, the time when the intake valve is fully open falls, and the value of the fresh charge entering the cylinder falls, and, as a result, M _max and P _max , the internal combustion engine does not “accept” at high speeds. To increase the charge at high revs of the HVC, it is necessary to start opening as early as possible to the TDC, increasing the angle α ₃ and accordingly increasing the valve overlap φ ₃₄ . However, at the same time (see Figure 1), the exhaust gas, being under increased pressure, begin to exit (“shoot”) into the intake pipe. Then they climb back into the cylinder at the intake stroke and, starting from a certain value of α ₃ , φ ₃₄ , the growth of the fresh charge stops.

As noted in / 1 / - "in most cases, high-speed engines have wider valve timing than low-speed engines." In domestic ICEs, for example, for VAZ 2121 ICEs, α ₃ = 12.5 °, and for VAZ 2108 α ₃ = 33 °, the latter has higher maximum revolutions and specific power.

Thus, at low, medium and high speeds, the internal combustion engine must be operated with its specific gas distribution phase angles in order to obtain minimum toxicity and maximum power and torque.

Recently, in the automotive industry, ICE with "variable valve timing" has been increasingly used. Almost all well-known companies - BMW, Honda ... developed their own versions of mechanical, electromechanical, etc. systems (CIFG).

Changes in the valve timing over a wide range of revolutions are achieved, as noted, for example, in / 2 / either by turning the camshaft, or by using special-profile cams that control several intake and several exhaust valves of one cylinder. The effectiveness of SIFG today is such that, for example, with toxicity according to the Euro 3 standard, such ICEs have a specific power of 125 hp. per 1 liter of naturally aspirated volume.

It should be noted that the more effective the mechanical SIFG, the naturally more complex, expensive and more cumbersome it is. In some types of internal combustion engines, up to five valves per cylinder are used.

A known method of forced purging of the COP with high pressure air.

For example, ICE is presented in / 3 /, in which the compressor is blown with high pressure air from an external compressor at the end of the exhaust stroke - the beginning of the intake stroke. Compressed air is supplied to the cylinder.

In ICE / 4 / - the prototype, the compressor is also blown with high pressure air, but purging, unlike / 3 /, occurs in the most optimal direction - from the inlet to the outlet valve.

This internal combustion engine 9 cm. FIG. 3) contains all the components of the internal combustion engine of FIG. 1, but additionally an uncontrolled purge check valve 9 (hereinafter OK 9) is installed in the intake manifold. Between OK 9 and VPK 3 a volume is formed - according to / 4 / - the purge receiver (hereinafter RP). ICE is shown at the end of the exhaust stroke, the piston almost reaches TDC, the spark plug, throttle and fuel injector are not conventionally shown.

ICE works as follows (see additional diagram of Figure 4).

At the end of the intake stroke after the BDC - the beginning of the compression stroke, when a full charge of air is accumulated in the cylinder, under the influence of increasing pressure in the total volume V _c + V _rp OK 9 closes as the piston moves upward, for example, when the pressure reaches P = 2 , VPK 3 closes and high pressure air P = 2 is stored in the RP.

Compression continues in cylinder 1, followed by strokes of the stroke and exhaust. At the end of the exhaust stroke, VPK 3 opens and the compressor is purged with high pressure air from the RP over the angle of the valves φ ₃₄ closure. Then, after closing OFF 4, the intake stroke begins on the piston moving down, OK 9 opens under the action of vacuum in the cylinder.

As noted in / 4 /, depending on the specific operating mode of the internal combustion engine, the following is selected:

V _rp = (0.5 ÷ 4) V _ks .

The pressure P _rp the higher, the greater φ ₃₄ .

Thus, for example, at a compression ratio of 10, P _rp = 2 and V _rp = 4 V _ks, about 30% of the cylinder volume will work to create an increased purge air pressure, which will reduce the liter capacity of the internal combustion engine by the same amount.

Then, the purge begins at the moment of ajar VPK 3 and over the angle α ₃ to TDC P _rp provides back pressure on the piston 2, reducing the moment of the internal combustion engine.

The early opening of the HVC 3 will lead to the fact that the purge air does not blow out the exhaust gas, but the exhaust, which already exits independently, and the exhaust gas will still remain above the piston after TDC.

Under these conditions, it is desirable to constructively reduce the value of α ₃ , starting to open VPK 3 as late as possible. At the same time, the CS can be well cleaned of exhaust gas, but by the time the intake starts 3 will not be completely open, and the cylinder will not gain a full charge of air at high speeds, this will further reduce the specific power of the engine.

The check valve in this application is usually one or more spring-loaded petals. To open them completely, it is necessary to expend some energy of the internal combustion engine. Due to the return force on the lobe, the check valve introduces tangible resistance to air flow, opens with some delay, and closes ahead of schedule. In general, this reduces the maximum charge of the cylinder.

We also note that OK 9 opens after the TDC of the intake stroke.

The purpose of the invention is the increase in specific power while maintaining low toxicity of internal combustion engines.

The goal is achieved by the fact that in the intake manifold, instead of a non-return valve, a valve is used that is controlled by its cam from the common camshaft with or without SIPG.

ICE (see Figure 5) contains a cylinder 1 with a piston 2, Vpk 3, Vyk 4. The valves are driven by cams 5 of the camshaft 6. The piston 2 rotates the crankshaft through the connecting rod 7 8. A purge valve is located at the inlet pipe a short distance from the Vpk 3 10 (KP 10). Structurally, it is similar to VPK 3, it is controlled by its cam from the camshaft 6. The passage section of KP 10 is fundamentally larger than that of VPK 3. The volume between VPK 3 and KP 10 is according to / 4 / - a purge receiver (RP)

ICE is shown in the state of the end of the exhaust stroke, the piston does not reach the bottom of the TDC. Spark plug and fuel injector are not conventionally shown.

ICE works as follows (see additional diagram, Fig.6).

At the end of the exhaust stroke (for example, with the position of the piston bottom — I), VPK 3 and KP 10 are closed, the pressure in the RP is approximately equal to atmospheric P _RP = 1, the exhaust through the open VYK 4 goes up to the exhaust manifold by moving the piston up. The pressure above the piston is even higher than atmospheric _Pg > 1. Further, without reaching TDC 30 ° -40 ° or more, VPK 3 begins to open, KP 10 remains closed. Since _Pg > P _rp , the exhaust gases penetrate into the RP and compress the air there as a spring (the region of compressed air is shown by dots). As expiration exhaust _og P falls, the volume of compressed air in the original RP increases and displaces the exhaust gas from RP back to the COP. Further, they also exit the CS through VC 4.

Then, for example, 10 ° before the TDC (moment II), open gearbox 10 and the compressor is blown with air from the RP and the inlet pipe. Then, with open VPK 3, KP 10 and closed Vyk 4, the cylinder charges on the piston moving down to the point III a little later than BDC. At this moment (it corresponds to the maximum cylinder charge at high revolutions), VPK 3 closes, and at the same time, or somewhat later (moment IV), KP 10 closes. At the same time, in the RP, there is basically no increased pressure, the internal combustion engine does not spend energy on this.

Thus, VPK 3 can be started to open very early before TDC, so that when approaching the closing time of VK 4 it would be completely open, while KP 10 is not yet fully open, but the flow through it is the same as through VPK 3 due to the initially larger structural bore. To do this, the KP 10 plate is selected with a large diameter, it has a large stroke and, when opened (moving down), additionally pushes air through the RP in the compressor station.

The force of the return springs KP 10 can be selected several times (up to an order of magnitude) less compared to the VPK 3, since the KP 10 is located outside the cylinder and it does not set the task of providing compression at high temperatures and pressures.

The presented ICE, for which, for example, α ₃ = 50 °, for VPK 3 has the same toxicity (low) as the classic ICE α ₃ = 10 ° for VKK 3. This provides a CP of 10 with α ₁₀ = 10 °. This design allows you to increase maximum speed, and therefore maximum power, even in the absence of SIFG.

SIFG (if used) works in light conditions. It controls only one valve (KP 10), decreasing at low revs and increasing it at high.

According to the diagram, Fig.6, one KP 10 can be used for two adjacent to the cylinder, working through the clock with a common intake pipe, subject to the conditions: V _rp ≈V _ks .

Literature

1. V.A. Stukanov. Fundamentals of the theory of automobile engines and automobiles: a training manual. - M .: FORUM: INFRA-M, 2004, p. 55.

2. A. Fomin and A. Vorobyov-Obukhov. The camshaft is retired. - “At the wheel”, 1998, No. 11.

3. Auto USSR No. 705133, class G02B 25/20.

4. Auto USSR No. 889878 (prototype), class G02B 29/00.

Claims (3)

1. Four-stroke internal combustion engine (ICE), comprising a power system, an ignition system, a variable valve timing system (SIFG), at least one cylinder, a piston kinematically connected to the crankshaft; a purge valve located in the inlet pipe; a camshaft through the cams leading the inlet and outlet valves located in the cylinder and a purge receiver located between the purge valve and the intake valve, characterized in that, in order to increase the specific power, while maintaining the level of toxicity, the purge valve is driven by the cam from the common camshaft at with or without CIHF, the intake and exhaust valves are driven without CIHF, the purge valve can open both before and after the top dead center of the intake stroke, the inlet valve opens as a minimum m at 10 ° before the purge valve, thus connecting the combustion chamber with a purge receiver and closes later or simultaneously with it, after the bottom dead center intake stroke. 2. ICE according to claim 1, characterized in that the diameter and flow area of the purge valve is larger than that of the inlet valve. 3. ICE according to claim 1, characterized in that one purge valve is used for two adjacent cylinders operating through a cycle with a common intake pipe.

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