JP3059206B2 - Reciprocating piston type internal combustion engine cylinder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cylinder of a reciprocating piston type internal combustion engine.

BACKGROUND OF THE INVENTION From DE 1216612 A1 it is known that the cylinder wall has grooves between the annular spaces defined by the piston rings for pressure compensation, these grooves being at one bottom dead center. Cylinders of reciprocating piston internal combustion engines are known which are arranged to extend beyond the range of the upper piston ring. This known device attempts to release the pressure in the piston ring intermediate space mainly to the combustion chamber.
The disadvantage of this known device is that, due to the relatively large axial dimensions of the groove, the lower annular space can be subjected to a relatively high pressure level in the immediately above annular space during the lowering of the piston during the expansion stroke. It is. Instead of reducing the pressure in the annular groove, the confinement pressure is raised to a relatively high level, which prevents the timely replacement of the piston ring from the side,
The danger of "hard biting" of the piston ring increases.

[Problems to be Solved by the Invention] An object of the present invention is to configure a cylinder of a reciprocating piston type internal combustion engine such that the sealing effect of a piston ring set is improved and the life thereof is enhanced while maintaining a perfect function. It is in.

According to the present invention, there is provided a combustion chamber defined by a reciprocating piston at an upper portion, wherein the piston supports a piston ring in a plurality of annular grooves. In a cylinder of a reciprocating piston type internal combustion engine, wherein an upper surface or a lower surface of a ring forms a plurality of annular spaces in relation to a piston side wall and a cylinder sliding surface and has a plurality of cavities disposed on the cylinder wall. Is configured as a buffer chamber,
The total volume of these buffer chambers is three to four times the volume of the annular space present between the piston rings, such that the top piston ring is below the buffer chamber at bottom dead center.
The buffer chamber is arranged on the cylinder wall at a height such that the bottom piston ring is above the buffer chamber at the top dead center, and the buffer chamber is in the piston longitudinal direction that matches the height of the piston ring sealing surface. It has a spread.

[Function and Effect] The annular space between the piston rings is appropriately filled with air one after another in the compression stroke by the buffer chamber arranged on the cylinder wall. The pressure in the top annular space is then highest and falls downward. The enclosed air acts as a blocking fluid against the ingress of combustible gases and particles into the piston ring set during the expansion stroke. In the second half of the expansion stroke, the enclosed atmosphere is again released from bottom to top, one after another, into the buffer chamber, so that the load on the annular space is removed and what prevents the timely replacement of the compression ring from the side. Absent. After the passage of the first compression ring, the buffer chamber is released toward the combustion chamber, with the added advantage that combustion residues penetrating into the region of the piston head side wall are carried back into the combustion chamber. The proportion that the second and third compression rings assume from the total pressure difference between the combustion chamber and the crankcase is increased by the invention, whereby the load on the first compression ring is reduced and its wear is significantly reduced. .

Advantageous embodiments of the invention are described in the dependent claims.

Embodiment Next, the present invention will be described in detail with reference to the drawings showing a plurality of embodiments of a cylinder according to the present invention.

1 to 9, a piston of a reciprocating piston type internal combustion engine (not shown) is indicated by reference numeral 1 and a cylinder is indicated by reference numeral 2. The end face of the piston 1 defines a combustion chamber 3. The annular gap 4 between the side wall of the piston 1 and the cylinder 2 is sealed by three piston rings 6, 9, 12 and one oil seal ring 15. A first piston ring 6 provided closest to the combustion chamber 3 has an annular groove 5 cut into the piston 1 and a second piston ring 6.
The piston ring 9 is fitted in the annular groove 8, the third piston ring 12 is fitted in the annular groove 11, and the oil seal ring 15 is fitted in the annular groove 14. All piston rings 6, 9, 12 and oil seal ring 15 are slightly smaller in their height than the axial dimensions of the annular grooves 5, 8, 11, 14 which house them. The piston rings 6, 9, 12 and the oil seal ring 15 respond to the forces applied to these rings (inertia force due to piston acceleration, pressing force corresponding to the pressure difference between the upper and lower surfaces of the piston ring, frictional force of the cylinder wall). To contact the upper surface or the lower surface of each of the annular grooves 5, 8, 11, 14. In the annular gap 4 between the piston 1 and the cylinder 2
And the second piston ring 6, 9 define a first annular space 7, and the second and third piston ring 9,
The second annular space 10 is defined by 12, and the third annular space 13 is defined by the third piston ring 12 and the oil seal ring 15.

In these annular spaces 7, 10, 13 a pressure is generated due to gas unavoidably leaking from the piston ring, which pressure is higher in the first annular space 7 than in the second annular space 10, It is higher in the second annular space 10 than in the third annular space 13.

FIG. 10 shows the pressure profile in the combustion chamber 3 and in the annular spaces 7, 10, 13 during the half-cycle, ie the compression and expansion strokes.

The pressure course in the combustion chamber 3 is indicated by the symbol p ₀ ,
The curve indicated by p ₁ ′ shows the pressure course in the first annular space 7, the curve indicated by p ₂ ′ shows the pressure course in the second annular space 10, and the curve indicated by p ₃ The curve shown shows the pressure course in the third annular space 13, where
p ₁ ′ and p ₂ ′ indicate a state where the present invention is not applied. The pressure p ₃ in the third annular space 13 differs only slightly from the pressure in the crankcase due to the weak sealing effect of the oil seal ring on the gas. Therefore, they are ignored in the following discussion.

As is well known, the pressure profile p ₀ in the combustion chamber 3 rises during the entire compression stroke, reaches a maximum just after the top dead center due to the propagation of the flame front by ignition and then continues during the remaining expansion stroke. Drops again. In contrast, the pressure rise p ₁ ′ in the first annular space 7 occurs with a large delay due to the strong throttling effect of the first piston ring 6 and the curve p ₂ ′ of the second annular space 10. Is reached further later due to the throttle effect of the second piston ring 9. In the region where the curves p ₁ ′ and p ₂ ′ exceed the descending curve of the curve p ₀ , the first and second curves
A confinement pressure is enclosed in the annular space 7 or 10, respectively, which prevents an orderly alternating of the compression rings. From the intersection of the curves p ₁ ′ and p ₀ , the first piston ring 6 is pressed against the upper side surface of the annular groove 5 by the confinement pressure, and the second piston ring 9 is pressed against the lower side surface of the annular groove 8. . Exhaust gas is enclosed in the first annular space 7 like a line with a double check valve, cannot be released in a timely manner during the expansion stroke and cannot clean the annular groove.
The amount of dirt particles that accumulates with each expansion stroke increases, and eventually the radial movement of the second piston ring 9 is impeded, thereby losing its function (ring congestion).

The uppermost piston ring 6 in the known piston / cylinder arrangement almost exclusively supports the total pressure difference between the combustion chamber and the crankcase during the entire compression stroke and during most of the expansion stroke. Since the pressure difference between the combustion chamber 3 and the first annular space 7 is almost crucial to the effective pressing force of this ring against the cylinder wall, this high burden necessarily leads to a large premature wear. Invite.

According to the invention, a buffer chamber 16 is provided in the wall of the cylinder 2 and the volume of these buffer chambers is a multiple of a total of one annular space 7, 10, 13 in total. The piston ring 6 at the top is located below the buffer chamber at the bottom dead center, and the piston ring (oil seal ring 15) is located above the buffer chamber at the top dead center. The buffer chamber 16 is disposed on the cylinder wall. Buffer room is first
In FIG. 9 to FIG. 9, the holes are formed as cylindrical holes distributed uniformly along the circumference and extending on one plane perpendicular to the cylinder axis.

1 to 9, the operation of the buffer chamber 16 will be explained at each point in the compression and expansion strokes. The pressure profile occurring in the individual annular spaces 7, 10 at this time is shown in FIG.
It indicated by p ₁ or p _2. The situation corresponding to FIGS. 1 to 9 is indicated in FIG. 10 by vertical lines, which are indicated by the same Roman numerals corresponding to the numbers in FIGS. 1 to 9.

In FIG. 1, the buffer chamber 16 is filled with the compressed air in the compression stroke. In FIG. 2, the first piston ring 6 passes through the inlet of the buffer chamber 16. The first annular space 7 is then filled with atmosphere having a somewhat lower pressure level than has risen in the combustion chamber 3 by this point. The pressure in the first annular space 7 is thereby reduced by the line in FIG.
II is raised to sudden level p ₁ as indicated by the height, the level p ₁ is significantly higher than the level p ₁ 'occurring in the same annular space when not using the buffer chamber based on the present invention.
Pressure difference between the pressure p ₁ of the combustion chamber pressure p ₀ in the first annular space 7 (p ₀ -p _1), when the piston is further moved from this point, the combustion chamber pressure p ₀ It is significantly smaller than the pressure difference between the annular space pressure p ₁ ′ to which the present invention is not applied.

However, the pressure difference across the first piston ring 6 is
It is a measure for the rate at which the ring undertakes sealing at the total pressure difference between the combustion chamber and the crankcase. This is because the pressure difference mainly determines the radial pressing force of the ring against the cylinder wall when the piston is tilted.

In FIG. 3, the second piston ring 9 is connected to the buffer chamber 16.
Through the opening. As a result, the second annular space 10 becomes the tenth annular space.
As shown by the height of the line III in FIG., The same (see curve p ₂ ') pressure generated therein at the time suddenly is increased from the very high pressure level p ₂ when not applying this invention. As a result, the second compression ring 9 takes on a relatively large share of the total sealing effect of the ring set, which averages out the wear of all piston rings and thereby the highest load on the first. Contributes to a reduction in wear of the piston ring 6.

In FIG. 4, the third piston ring 12 is
Through the opening. As a result, the residual pressure existing in the buffer chamber 16 is released into the third annular space 13, and in the annular space 13, the atmospheric pressure is substantially reduced due to the small sealing effect of the oil seal ring 15 and the exhaust of the crankcase. Occurs. The complete release of the slight residual pressure from the buffer chamber 16 takes place at the moment shown in FIG. 5 in which the oil seal ring 15 passes through the opening of the buffer chamber 16.

During the subsequent course of the compression stroke, the pressure levels in the annular spaces 7, 10 are further increased, in particular by the air squeezed out of the combustion chamber 3 via the ring seam. At the first stage of the next expansion stroke (see FIG. 6), the atmosphere enclosed in the annular spaces 7, 10 allows combustible gases and combustion residues to enter the piston ring set and to the crankcase. Form an effective barrier to (blow-by).

In FIG. 7, the third piston ring 12 passes through the opening of the buffer chamber 16 during the downward movement, and the second annular space 10
And the buffer chamber 16 can be connected. At that time, the second annular space
The pressure at 10 suddenly drops to a significantly lower pressure level as shown by line VII in FIG.

Immediately thereafter (see FIG. 8), the second piston ring 9 passes through the opening of the buffer chamber 16. The line VIII in Fig. 10
, The pressure in the first annular space 7 suddenly drops to a significantly lower pressure level. Due to the timely release of the pressure trapped in the annular spaces 7, 10, the curves p ₁ ′, p ₂ ′
The piston ring changes the contact surface in each piston ring in a timely manner based on the frictional and inertial forces, since pressure overshoots such as that above the curve p ₀ and to the right in FIG. 10 are avoided.

In the state shown in FIG. 9, the first piston ring 6
Pass through the opening of the buffer chamber 16. At that time, buffer room 16
Stored in the combustion chamber 3 through a narrow gap between the upper edge of the buffer chamber opening and the upper edge of the piston ring 6 and subsequently through an annular gap 4 along the piston head side wall. Escape to. It is advantageous to carry it back to the combustion chamber 3 with the combustion residues that happen to be there, thereby keeping the ring set functioning very cleanly.

Next, a plurality of modified examples of the shape and arrangement of the buffer chamber will be described with reference to FIGS. 11 to 13. In Fig. 11,
The buffer chamber is formed as an elongated pocket 17 whose longitudinal axis extends mainly on a plane arranged perpendicular to the piston axis 18. Thereby, the cross section of the buffer chamber and therefore its volume is increased compared to the cylindrical bore of the previous embodiment, without having to increase the size of the bore in the piston longitudinal axis which is adapted to the height of the piston ring sealing surface. The advantage that arises. For all embodiments, all buffer chambers together have a volume that is several times, preferably about three to four times, the volume of one annular space 7, 10, 13. Such a match results in advantageous pressure rises and drops in the annular space, as shown in FIG.

In FIG. 12, buffer chambers formed as cylindrical holes 19 are arranged on the saddle-shaped surface line 20 of the cylinder sliding surface so as to be shifted from each other in the axial direction of the cylinder 2. As a result, the filling and discharging of the annular spaces 7, 10 are not abrupt as in the first embodiment, but from the highest point of the highest hole 19a to the lowest point of the lowest hole 19b. A smooth transition occurs during the movement interval of the piston to reach.

In the case of another embodiment shown in FIG.
Buffer chambers 21 and 22 are parallel to each other and the cylinder axis
It is arranged on two planes perpendicular to 23. In this embodiment, a two-stage filling and discharging of the annular spaces 7, 10, 13 takes place. The pressure profile of the first annular space 7 indicated by the curve 24 in FIG. 14 and the second curve indicated by the curve 25 in FIG.
The pressure course of the annular space 10 is already known from FIG.
It is relatively similar to the shape of the pressure profile of the combustion chamber 3 with p ₀ . Thus, the pressure difference between the combustion chamber 3 and the crankcase during the illustrated part of the working cycle of the engine is:
It is distributed to both compression rings 6, 9 in a proportion which remains almost constant, which contributes to the uniform loading and wear of these rings.

[Brief description of the drawings]

1 to 9 are cross-sectional views showing the relationship between a piston ring and a buffer chamber in an embodiment of a cylinder according to the present invention at each stage of a compression and expansion stroke, and FIG. FIG. 1 to FIG. 9 are graphs showing the pressure course in the annular space between the combustion chamber and the piston ring shown in FIG. 1 with respect to the presence or absence of the buffer chamber, and FIG. 11 to FIG. And FIG. 14 is a graph showing the pressure course of the cylinder shown in FIG. 13 in the same manner as in FIG. DESCRIPTION OF SYMBOLS 1 ... Piston 2 ... Cylinder 3 ... Combustion chamber 5, 8, 11, 14 ... Annular groove 6, 9, 12 ... Piston ring 7, 10, 13 ... Annular space 15 ... Oil seal ring 16, 17, 19, 21, 22: Buffer chamber 18, 23: Cylinder axis 20: Surface line

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02F 5/00 F02F 1/08 F02F 1/18

Claims (8)

(57) [Claims] An upper portion has a combustion chamber defined by a reciprocating piston, the piston supports a piston ring in a plurality of annular grooves, and the upper or lower surface of the piston ring has a piston side wall and a cylinder sliding surface. In the cylinder of a reciprocating piston type internal combustion engine, which forms a plurality of annular spaces in relation to, and has a plurality of cavities arranged on the cylinder wall,
The empty space is configured as buffer chambers (16, 17, 19, 21, 22), and the total volume of these buffer chambers is 3 to 4 times the volume of the annular space (7, 10, 13) existing between the piston rings. Such that the uppermost piston ring (6) is below the buffer chamber at the bottom dead center and the lowermost piston ring (12) is above the buffer chamber at the top dead center. Now, the buffer chambers (16, 17, 19, 21, 22) are arranged on the cylinder wall, and the buffer chambers (16, 17, 19, 21, 22) have the piston length adjusted to the height of the piston ring sealing surface. A cylinder of a reciprocating piston type internal combustion engine, characterized by having a directional spread. 2. A cylinder according to claim 1, wherein a blind hole extending radially in the cylinder wall is used as the buffer chamber. 3. The cylinder chamber as the buffer chamber.
Elongate pocket with longitudinal axis extending perpendicular to it (17)
The cylinder according to claim 1, wherein: 4. The cylinder according to claim 1, wherein a plurality of buffer chambers (16, 17, 19, 21, 22) are uniformly distributed around the periphery. . 5. The cylinder according to claim 1, wherein all the buffer chambers are arranged on a plane extending perpendicularly to the cylinder axis. . 6. The cylinder chamber according to claim 1, wherein all of the buffer chambers are disposed axially offset from each other on a saddle-shaped surface line of the cylinder sliding surface. A cylinder according to any one of the preceding claims. 7. The device according to claim 1, wherein the buffer chambers are arranged on two planes parallel to each other and perpendicular to the cylinder axis. Cylinder. 8. An axial height of the sealing surface of the piston ring (6, 9, 12) within a range of the buffer chamber opening on the cylinder wall in an axial dimension of the buffer chamber (16, 17, 19, 21, 22). 8. A cylinder according to claim 1, wherein the cylinder is slightly larger than the cylinder.