SU1765479A1 - Internal combustion engine with cylinder volume control - Google Patents

Abstract

Usage: engine. Summary of the Invention: an engine comprises a cylinder with pistons and a crank mechanism. The cylinder is equipped with a compensation piston, which is controlled by a hydraulic cylinder. The piston rod cavity of the hydraulic cylinder is connected to the spool valve, the valve of which is simultaneously connected through a screw pair to the drive shaft, and through a spline coupling to the output shaft of the summing mechanism, and the input shafts of the latter are connected respectively to the vacuum sensor and the centrifugal sensor, the pressure source is the hydraulic pump . 2 hp f-ly, 4 ill.

Description

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The invention relates to the field of engine building, in particular, to the construction of a piston engine with an adjustable volume of combustion chambers, and can be applied to engines with variable operating conditions, for example, in automobiles.

Known internal combustion engines with an adjustable volume of combustion chambers, for example, an internal combustion engine in a.s. No. 1314135 F 02 D 15/04.

The disadvantage of this engine is the increased mass of the gas distribution mechanism, combined with the mechanism for changing the volume of the combustion chambers, and the lack of automatic control of the latter.

The known structure of an internal combustion engine with an adjustable volume of the combustion chamber by means of a compensation piston installed in the head

the cylinder can be moved in the hydraulic cylinder under the action of the pressure difference in the latter and the combustion chamber, (A.P. No. 983293 F 02 B 75/04, F 02 D 15/04). The disadvantage of this design is the considerable energy losses due to cyclic displacement of the compensation piston under the action of the pressure inside the cylinder that changes during the working cycle, as well as the technical difficulty of reliably sealing the piston of the hydraulic cylinder operating under high temperatures. The automatic adjustment of the volume of the combustion chamber in the engine, selected as a prototype, is carried out depending on the throttle position in the intake manifold. Such regulation is not effective enough, since the degree of filling of the engine cylinder with a combustible mixture only indirectly depends

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from throttle position. The optimum degree of compression is in direct linear dependence on the magnitude of the vacuum in the engine intake manifold and in inverse linear dependence on the frequency of rotation of the crankshaft. Therefore, it is more effective to control the volume of the combustion chamber depending on these parameters.

The aim of the invention is to increase the fuel efficiency of the engine by automatically adjusting the degree of compression depending on the mode of operation.

The goal is achieved by the fact that the internal combustion engine, which contains working cylinders with pistons, a gas distribution mechanism, an intake and exhaust manifolds, a throttle valve located in the intake manifold and controllable compensating pistons mounted in the cylinder head of each cylinder, is equipped with centrifugal and vacuum sensing elements which, via a summing mechanism, are connected with a slotted coupling to a spool distributor of a hydraulic actuator including a hydraulic cylinder piston and rod forming piston and rod cavities connected to the spool valve, hydraulic cylinder rod is articulated with one arm of two shoulders formed by the drive shaft with drivers fixed on its axis, and the second arm with compensating piston rods, the distributor spool is connected to the drive shaft shaft and summing mechanism. The summing mechanism is made in the form of a differential gear reducer.

The connection of the distributor valve with the drive shaft is made in the form of a screw pair, and with a summing mechanism in the form of a splined coupling.

The analysis of the solutions known in this field allows to conclude that there are no signs in them that are similar to the significant distinguishing features in the claimed internal combustion engine, and to recognize the proposed technical solution corresponding to the criterion of significant differences.

In contrast to the known engines with an adjustable compression ratio, which is changed depending on the magnitude of the gas pressure in the working cylinder and the throttle position, the proposed engine automatically adjusts the volume of the chambers.

combustion depending on the amount of vacuum in the intake manifold and the frequency of rotation of the engine's crankshaft, i.e. depending on parameters that directly affect the gas pressure inside the cylinders at the end of the compression stroke, which in turn determines the degree of compression.

FIG. Figure 1 shows the kinematic scheme of an internal combustion engine with an adjustable volume of combustion chambers.

The engine contains a cylinder 1 with a working piston 2 and a crank mechanism 3. In the intake system of the cylinder, there is a throttle valve 4. The cylinder head is equipped with compensation pistons 5 (only one is shown in figure 1). Each compensating piston with a two-armed lever,

0 formed by a drive shaft 8 with drivers 7 rigidly attached to its axis, is connected to the rod 9 of the hydraulic cylinder 10. The drive shaft is kept in the initial position with the engine off

5 return spring 11.

Piston and rod cavity of the hydraulic cylinder 10 are connected by pipelines with a spool valve 12, equipped with a spool 13, which by means of

0 of the rod 14 through a screw pair 15 is connected to the drive shaft 8, and through the slotted coupling 16 - with the output shaft 17 of the summing mechanism 18. The input shaft 19 of the summing mechanism with the help of the lever 20

5 is connected to the stem 21 of the vacuum sensing element 22, the working cavity of which communicates with the intake manifold 23. The input shaft 24 of the summing mechanism is connected by means of a lever 25 and a leash

0 26 with a centrifugal sensing element 27 receiving rotation from the camshaft of the engine timing mechanism.

Between slotted 16 clutch and weekend

5, the shaft 17 of the summing mesanism is fitted with a transversely folding coupling 28, which acts as an octane corrector.

The hydraulic cylinder 10 receives power from the hydraulic pump 29, the rotor of which receives

0 rotation from the engine crankshaft.

The engine works as follows.

In the initial position with the engine off, the compensation piston

5 5 is at the top of the stop, held by the compression spring 11. The stem 21 of the vacuum sensor is pushed up to the stop, the loads of the centrifugal sensor are closed, the spool 13 is in the neutral position. After launch

When the engine at a low rotational speed of the crankshaft, the vacuum sensing element pulls the rod 21 to its lowest position, the weights of the centrifugal sensing element continue to remain closed.

By rotating the shaft 17, the screw of the screw pair is unscrewed and displaces the spool 13 to the right, connecting the lower (piston) cavity of the hydraulic cylinder 10 with a pressure line and turning the shaft 8 by an angle equal to the angle of rotation of the shaft 17.

The compensation piston is lowered all the way down. The degree of compression reaches the maximum value

With a sharp full opening of the throttle valve 4, the vacuum in the throttle space of the engine intake manifold decreases, the stem 21 of the vacuum sensing element is extended, turning the shaft 17 through the summing mechanism 18 and screwing the screw of the screw pair 15, thereby shifting the spool 13 to the left of the neutral position.

The upper (rod) cavity of the hydraulic cylinder 10 is connected to the pressure line, turning the shaft 8 at exactly the same angle as the shaft 17 is turned, and raising the compensation piston 5 upwards, thereby reducing the compression ratio of the engine and preventing detonation.

With an increase in the crankshaft rotational speed from 0.4 pmax to pmax, the centrifugal sensing element 27 operates, the loads of which diverge with increasing rotation frequency. Respectively, the summing mechanism 18, screw pair 15, spool 13, hydraulic cylinder 10, raise the compensation piston 5, thereby compensating for its lowering, caused by an increase in vacuum in the intake manifold due to an increase in the frequency of rotation of the crankshaft. Thus, when the engine is running at full throttle, the compression ratio from 0.4 pmax to Pmax remains minimal, preventing detonation.

As the opening of the throttle valve is reduced, the vacuum in the intake manifold increases, the vacuum sensing element is actuated by the appropriate amount of movement of the rod 21, moving the compensation piston downwards, increasing the compression ratio by the required value.

When the throttle valve is completely closed (the engine is idling) the rod 21 of the vacuum sensing element is fully retracted, the compensation piston is lowered down to

stop, the degree of compression reaches a maximum value. By reducing the amount of combustible mixture supplied to the engine cylinders, the rotational speed of the crankshaft drops

If the throttle valve is partially covered when the engine is running at maximum speed, the compression ratio will increase accordingly, and then

As the frequency of rotation of the crankshaft decreases, a decrease in the compression ratio will occur due to the joint operation of the vacuum and centrifugal sensing elements.

When the engine is stopped, at first, despite the fall in crankshaft speed, the vacuum in the intake manifold continues to remain high. Vacuum sensor holds

compensation piston 5 in the lower position. After the engine is completely stopped, the vacuum disappears, the rod 21 of the vacuum sensing element is extended, turning the screw of the screw pair 15 and shifting

spool 13 left. The spring 11 returns the compensation piston 5 to the upper initial position. To prevent this movement from interfering with the hydraulic fluid in the cylinder 10, an overflow check valve 30 serves to allow the hydraulic fluid to flow from the lower cavity to the upper one when the hydraulic pump 29 is stopped.

To prevent damage to machinery

The control systems for the transmission of rotation from the shaft 8 to the shaft 17, which can occur when the engine is stopped, serve as buffer springs 31.

The operation of the coupling 28, serving as

octane-corrector, based on a change in the initial mutual angular position of the drive shaft 8 and the stem 14, thereby changing the limits for adjusting the volume of the combustion chambers. This is necessary in case

transfer of the engine to fuel with an octane rating different from the calculated one.

The calculation of the basic parameters of the engine is as follows.

The maximum allowable degree of compression is determined by the formula:

Јk Ј0 / V10PK,

where Ј0 is the degree of compression of a similar but unregulated engine;

Pk - pressure in the cylinder at the end of the intake, MPa.

Using a known diagram, determine the Pc value for the carburetor

engine naturally aspirated when n const depending on the OT 7 / j.

The limits of regulation are chosen from a known graph. If we restrict ourselves to adjustments ranging from figfg 0.3 (relative opening of the throttle) to (wgfg) 1.0, then at n 1.0 (wgfg) 0.3, / i 0.35, according to Pk schedule 0.05 MPa .

Then, for an engine with Ј0 8.8, when equipping it with the proposed control system, the maximum permissible compression ratio ek max 8.8 / V 10-0.05 12.5 can be accepted.

At the same time, the relative indicator efficiency will increase from t} 1.05 to fj 1.15.

Thermal efficiency calculated by

formula D). 1 - ----, with k 1.3 it will increase from d 0.47 to 7t 0.53.

To calculate the automatic control system of the compression ratio of the proposed engine, it is necessary to have the following initial data:

1. Graph of the dependence of the filling ratio j / i on the negative pressure A Pk r) f (A Pk) in the engine intake manifold in the throttle space.

This relationship is linear and is expressed by the formula g a - b Pk, where a and b are experimental coefficients.

Graphically, this appears as shown in FIG. 2,

a on;

b-.gr - &

2. Graph of the dependence of the filling ratio rj on the engine crankshaft rotation frequency and the relative value of the throttle valve opening.

3. Graph of the pressure of the combustible mixture inside the cylinder at the end of the compression stroke versus the crankshaft rotation frequency at 7 / j const (see Fig. 3).

With sufficient accuracy for practice, this dependence can be assumed linear, and the maximum relative increase in Pc

by increasing the pressure

with max

Neither the rotational speed within the regulation n 0.4-1.0 is equal to the relative decrease of the filling ratio D

     1.0 Max

4. Limit values for adjustable compression ratio. Approximately determined by known data and the formula Јk Јo / V 10 Pk are refined experimentally during engine tuning.

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ten

15

20

25

thirty

35

40

45

50

55

The graph in figure 4 shows the main dependencies required for the calculation.

- Area, limited by points a, b, d, m - area of coverage of engine operating modes by regulation;

-O - S - displacement scale of the compensation piston;

-am is the magnitude of the change in the filling ratio at n 0.4 and opening the throttle valve within ("gfg) 0.3-1.0;

-se is the magnitude of the change in tj at n 1.0 and the opening of the throttle valve within (ugfg) 0.3-1.0;

-OZ is the displacement amount of the compensation piston due to the operation of the centrifugal sensing element when changing n 0.4-1.0;

-Ј is the extremum point of the f (n) curve with () 1;

-Or is the vacuum in the intake manifold, corresponding to the maximum displacement of the compensation piston.

To find the vacuum value in the intake manifold, and consequently, in the chamber of the vacuum sensing element corresponding to a given engine operation mode, for example, n 0.7 and (wgfg) 0.6, it is necessary to find the value 0 on the 0-n axis 7, climb vertically to the intersection with the curve ijv f (7T) at (Mgfg) 0.6, draw a horizontal line to the intersection with the scale 0-S and the line 7v f (A Pk) and descend vertically to the point t. The segment Oh-t on the axis 0-DRK will give the magnitude of the vacuum. The segment O-l on the scale 0-S will determine the amount of movement of the compensation piston from the initial position downward due to the operation of the vacuum sensing element.

The amount of movement of the compensation piston due to the operation of the centrifugal sensing element corresponding to the same mode of operation of the engine is determined by the segment b-c1 on a scale of 0-S.

Using the obtained values of vacuum and displacement of the compensating piston corresponding to the initial a, m and final b, c, d, e points of the control area, it is easy to calculate the diaphragm diameter and spring stiffness of the vacuum sensing element, the mass of the weights and spring stiffness of the centrifugal sensing element.

The most suitable in design centrifugal sensitive element

is the tachometer given in the book of I.Ya.Raikov Testing of internal combustion engines. M .: Higher School, 1975, §v.2, p.107, fig.V.I.

Claims (3)

Claim 1. The internal combustion engine with an adjustable cylinder volume, containing working cylinders with pistons, a gas distribution mechanism, intake and exhaust manifolds, a throttle valve located in the intake manifold and mounted in the head of each cylinder, controlled compensating pistons with a hydraulic actuator, that, in order to increase fuel efficiency, the engine is equipped with a summing mechanism, centrifugal and vacuum sensitive elements, the drive shaft, of a tight bound to the axis of rotation of the two-armed levers and connecting rods for each compensating piston hydraulic compensating piston adapted to, Y de spool valve and hydraulic cylinder with piston and rod, forming piston and rod cavities, connected to spool valve, hydraulic cylinder rod connected to one arm of two shoulders, the other shoulder of which is connected with compensating piston rods, double arm, gold the distributor is connected to the drive shaft and the summing mechanism, and the centrifugal and vacuum sensing elements are connected to the latter. 2. The engine according to claim 1, from l and h and yushchi and the fact that the summing mechanism is made in the form of a differential gear reducer. 3. The engine according to claim 1, characterized by the fact that the connection of the distributor valve with the drive shaft is made in the form of a screw pair, and with the summing mechanism in the form of a splined coupling. 0 PC B / W Fig.Z fly sj (uP) FIG. 2 & Rk n