RU2497002C2 - Piston machine - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: piston machine comprises cylinder-and-piston set including piston with compression rings fitted in its grooves and two bushes fitted in piston sidewall recesses as structural assemblies to orient ring locks. Said bushes are arranged above second compression ring in symmetry about its lock center at spacing between edges of recesses not exceeding preset maximum tolerance. Every said structural assy features limited displacement and is composed of a roller to enter holder top (annular) part with oil clearance and to slide between bottom holder end ledges, bottom holder being composed of segmented groove milled-out in piston body. Taper angles of top and bottom grooves in compression ring locks differ.

EFFECT: higher operating performances.

3 cl, 5 dwg

Description

The invention relates to the field of engineering, in particular to engine building and car repair, and can also be used in compressor equipment.

Analogs of the invention are widely known technical solutions for the design of the sealing elements of the cylinder-piston group of internal combustion engines (ICE).

The prototype of the claimed invention is a piston machine containing at least one cylinder-piston group including a piston with compression rings located in its grooves and at least two liners installed in recesses on the side surface of the piston, as well as structural units designed for mutually displaced orientation position locks rings. In this invention (2195563 C2, L.1), liners that block the flow of gas breaking into the locks of the rings in the stroke of the piston stroke are placed in the recesses on the piston body under the first compression ring at a distance of at least 8 mm between each liner and the axis of symmetry of the ring lock and ensure tightness of the seal in the area of the ring lock, and structural units for mutually offset orientation of the position of the ring locks are made in the form of stoppers embedded in the piston body in the annular grooves above the semicircular recesses in the rings at a distance of 1-6 mm about edge end portions of the rings.

With this geometry of the location of the liners and the design of the ring fixing elements in each cylinder-piston group of a four-stroke engine containing at least two compression rings, negative phenomena occur that reduce the effect of increasing the working qualities of intensively operated ICEs, namely:

1. At the beginning of the stroke of the working stroke in the lock zone of the first ("firing") ring, limited by the liners, the pressure in the cavity between them sharply increases. Accordingly, the pressure of the gases that press this part of the ring to the bottom wall of its groove sharply decreases, and the resulting imbalance of pressure at high engine speeds leads to increased vibration of the ring and to premature wear of the walls of its groove;

2. The thermal energy of gases breaking into the cavity between the rings is removed with significantly limited gates of the cooled surface of the cylinder;

3. During the intensive operation of the internal combustion engine, the stoppers of the first compression rings located in the zone of high pressure and temperature overloads, due to the formation of soot, tightly sit in the grooves prepared for them in the rings and deprive the rings of their mandatory mobility in the grooves.

The technical task of the invention is to improve the performance of the piston machine.

The problem is solved in that in a piston machine containing at least one cylinder-piston group, comprising a piston with compression rings located in its grooves and at least two liners installed in recesses on the side surface of the piston, as well as structural units for mutually offset orientation the positions of the locks of the rings, the liners are placed above the second compression ring, symmetrically with respect to the position of the center of its lock, with a distance between the inner edges of the recesses not exceeding a minimum no specified reserve. With such an arrangement of the liners, the front of the pressure wave of hot gases breaking through the thermal gap of the first compression ring propagates along the cavity bounded by the liners - shutters, slightly smaller than the circumference of the rings, and the pressure imbalance on the first compression ring in the stroke of the piston stroke decreases significantly, which allows to reduce the wear of the walls of its grooves due to vibrational phenomena and to increase the surface of heat transfer of gases into the medium cooling the outer walls of the engine cylinders.

The problem is also solved by the fact that the structural unit for the mutually displaced orientation of the position of the locks of the rings is made in the form of a roller entering the upper (annular) part with an oil gap and sliding with an oil gap between the end stops of the lower holder, made in the form of a segment groove milled into body of the piston. The use of a roller instead of a stationary stopper of a roller between two stops provides the property of limited mobility of the ring in the groove to significantly reduce the likelihood of its coking and increases the reliability and manufacturability of the fixing assembly. This property is reinforced by the fact that the upper and lower ends of the outer part of the lock, at least the first compression ring extending beyond the piston body, are shaped into two cones separated by a thermal gap. The ring lock thus profiled allows you to create a more laminar flow of bursting gases and reduce the likelihood of resonant vibration of the ring in the groove at increased engine speeds.

The problem is solved by the fact that the taper angles of adjacent upper and lower grooves in the lock of at least the first compression ring are different for creating a variable concentration of bursting gas forces, longitudinally shifting the ring within the limits specified by the roller stops and reducing the likelihood of ring coking due to the acquired new property. This property, if necessary, is enhanced by the fact that the upper and lower grooves in the lock are attached with a profile shape of a second-order curve. Creating the same profile for the gas passage as that of the Laval nozzle allows you to give the ring lock additional anti-vibration properties and properties to accelerate the passage of the gas pressure wave front through the lock gaps of the first compression ring to the liners and increase the efficiency of the liners (pneumodynamic locks).

The minimum specified margin between the inner edges of the indentations for the liners is set different for new and repair engines, taking into account the specified margin in increasing the thermal clearances in the lock of the second compression ring during long-term intensive operation of the engine and taking into account the specified distance between the end stops of the fixing roller, which ensures an effective the operation of the liners, regardless of the value of the gap in the lock of a limited-movable ring.

The invention is illustrated by the accompanying drawings: Figure 1-5.

Figure 1 shows a typical mechanism of action of the labyrinth seal of cylinders of commercially available engines in the form of an average dynamic diagram of the pressure of gases P breaking through the compression rings K into the crankcase as follows.

When the engine is running, the over-piston gases in compression, expansion and exhaust strokes penetrate under pressure P through the end gap above the first compression codec, pressed by this pressure to the bottom wall, first into the groove cavity between the ring and the piston and partially through the ring locks into the engine crankcase, and then, when at the intake stroke the first ring is pressed against the upper wall of the groove, flow into the cavity between the first and second compression rings. In the same way, gases penetrate into the cavity beyond the lower ring, gradually losing their pressure due to the throttling action of the gaps. It has been experimentally established that during operation of high-speed engines, the pressure in the cavity behind the first ring reaches 75%, and after the second 20% of the pressure in the cylinder above the piston.

With local overheating in the gaps between the rings and the walls of the grooves, slag micro-deposits are formed, which are blown together with the gases due to the mandatory mobility of the rings in the grooves (L.2).

Figure 2 shows the structural details of one piston group of the proposed piston machine. Figure 3 shows a cross-section of the piston and cylinder under the first compression ring and fragments of the proposed scheme of sealing resistance to bursting gases. Figure 4 shows the zone of the vertical section of the lock of the first compression ring in the plane AA, and Figure 5 shows the configuration of this section with a diagram of the pressure of bursting gases.

In accordance with the tasks, the cylinder-piston group of the proposed piston machine, consisting of a piston 1, cylinder 2, a first compression ring 3 and a second compression ring 4 placed in the respective piston ring grooves 5 and 6, is equipped with at least two liners 7 and 8 installed in the recesses 9 and 10 milled under each insert on the lateral surface of the piston 1 above the second compression ring 4, symmetrically with respect to the position of the center of its lock and structural units for limited movable mutually displaced (interconnected if there are only 2 compression rings on the piston) orientation of the position of the locks of rings 3 and 4, made in the form of a roller 11 included in the upper (annular) part of the cage 12 of the first ring 3 with an oil gap and a roller 13 included in the upper ( annular) part of the holder 14 of the second ring with an oil gap 15, which is not shown in FIG. 3 for the first ring. The lower clips of the rollers are segmented grooves 16, milled at the bottom of the piston grooves for each compression ring with end stops concave in the shape of the rollers, stops 17 with a distance between the stops, which constitutes (in particular) 2.5 sizes of the radius of the roller. The liners 7 and 8 and the corresponding recesses 9 and 10 in shape provide a tight, with a small oil gap, adherence of the ends of the liners to the surfaces of both rings, and one of the faces of each liner, when a pressure gradient arises between the faces, is pressed against the cylinder mirror and densely closes the cavity 18 from the breakthrough of gases into the lock of the second compression ring. The outer part of the lock of at least the first compression ring 3 is milled in the form shown in Fig. 4 and Fig. 5.

A piston engine as part of a 4-stroke engine works according to the following principle.

In the working cycle, there is a sharp increase in temperature and pressure in the cavity above the piston 1. Under the influence of expanding gas pressure, the first compression ring 3 fits snugly against the bottom wall of its groove 5 and closes the gas path through the end gaps. Gases breaking through the lock of the first compression ring 3, accelerated due to the lock configuration of this ring changed in accordance with FIG. 4 and FIG. 5, quickly fill the cavity 18 between the liners 7 and 8, press the second compression ring 4 to the bottom wall of its groove 6 , preventing the breakthrough of gases through the end gaps of this ring, and the outer edges of the liners 7 and 8 close the cavity 18 from the breakthrough of gases through the lock of this ring.

Since the exhaust gases are discharged from the cylinder 2 in the working cycle until the piston 1 arrives at bottom dead center, the pressure above the piston at the end of this cycle decreases sharply. However, due to the throttling action of the gap in the lock of the first compression ring 3, the accumulated pressure in the cavity 18 is sufficient to prevent gas breakthrough beyond the second compression ring 4 not only at the end of the operating cycle, but throughout the entire exhaust cycle, in which due to the throttling the effect of the pushed gases into the openings of the exhaust valve, exhaust manifold and muffler, the pressure above the port remains substantially higher than atmospheric, as well as in the intake stroke, in those phases when the pressure above the piston 1 get lower than atmospheric. In the compression stroke, the residual pressure in the cavity 18 begins to increase, increasing the effect of the gas shutter from a breakthrough for the second compression ring 4

The limited mobility of the first compression ring 3, which prevents its coking, is achieved by the fact that during the intensive inflow of gases at the beginning of the compression stroke through the lock of this ring into the cavity 18, due to the difference in the force vectors P1 and P2 (Figure 5) and still low over-piston pressure, the ring 3 on the roller 11 slightly rolls in the direction of one of the end stops of its segmented trough, and when gases flow out of the cavity 18 in the intake stroke, it rolls to the other side. The second piston ring 4, less prone to coking, can be used without a special groove of its lock, gaining limited mobility due to the mobility of the roller 13 in its segmented trench and the action of gas and inertial loads.

As the compression rings wear, the intensity of the sealing action of the parts of the proposed piston machine is maintained for a long time due to the constructive fulfillment of the condition

Rkv = Kv (Kpr Dr + Kt Rt),

where Rkv - the size value between the near edges of the recesses 9 and 10 for the liners 7 and 8; Dr - the value of the diameter of the roller 13; KPR - the value of the coefficient of mobility of the roller 13 in the groove 16; Rt is the value of the initial thermal gap in the lock of the second compression ring 4; CT is the value of the safety factor for increasing the thermal gap; Kv - the value of the coefficient of mobility of the liners 7 and 8 in the recesses 9 and 10 for the liners, taking into account the maximum allowable wear of these parts.

In contrast to the dynamics of the typical sealing mechanism of a cylinder-piston group of commercially available internal combustion engines (FIG. 1) and the sealing mechanism in the prototype device (L.1), the sealing mechanism of the proposed piston machine allows the use of supra-pressurized pressure to create a constantly acting shock-absorbing medium between compression rings , additionally preventing the breakthrough of gases into the crankcase of long-term and intensively operated internal combustion engines or compressor installations, eliminate the identified deficiency and and to solve the task in accordance with the proposed techniques.

The technical efficiency of the proposed piston machine is experimentally verified.

Information sources

1. Description of the patent RU 2192195563 C2, 2000.12.27.

2. The textbook "Tractors and cars", Rodichev VA, Rodicheva GI, second edition: Agropromizdat, 1987

Claims (3)

1. A piston machine containing at least one cylinder-piston group comprising a piston with compression rings located in its grooves and at least two liners installed in recesses on the side surface of the piston, as well as structural units intended for mutually offset orientation the position of the locks of the rings, characterized in that the liners are placed above the second compression ring, symmetrically with respect to the position of the center of its lock. 2. The machine according to claim 1, characterized in that each structural unit for mutually offset orientation of the position of the locks of the compression rings is made limited movable, in particular, in the form of a roller entering the upper (annular) part of the cage with an oil gap and sliding with an oil gap between end stops of the lower holder, made in the form of a segmented groove, milled in the piston body. 3. The machine according to claim 1, characterized in that the taper angles of the adjacent upper and lower grooves in the locks of the compression rings are made different.

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