JPS60216053A - Reciprocating internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the cycle efficiency by temporarily decreasing the lowering motion speed of sub-piston in the way of expansion stroke of piston. CONSTITUTION:Sub-piston 11 is reciprocative to slide between the sliding face 10 and the sideface. Cam 15 is formed at the small end section of conrod 4 along the outercircumference of piston pin 3. Upon rolling of conrod 4 around the piston pin 3 in the first half lowering stroke of piston pin 1, a roller 14 is pushed up through cam face to move the sub-piston pin 11 upward. In the way of expansion stroke of piston, the lowring motion speed of sub-piston is decreased temporarily to stop expansion and to gain time for completing the combustion resulting in improvement of cycle efficiency.

Description

[Detailed description of the invention] The present invention relates to reciprocating internal combustion engines.

FIG. 1 shows a conventional reciprocating internal combustion engine of this type.

In the figure, 01 is the piston, 02 is the cylinder 2 inner,
03 is the piston pin, 04 is the connecting rod.

05 is a crank pin, 06 is a crankshaft, and 07 is a combustion chamber space. Corresponding to the rotation of the crankshaft 06, the crank pin 05. A crank mechanism consisting of a connecting rod 04 and a piston pin 03 causes the piston 01 to perform reciprocating sliding motion along the inner surface of the cylinder liner 02. bis) yol
In the upward stroke of , piston 01 and cylinder liner 0
The gas in the combustion chamber space 07 formed at 2 is compressed and the temperature drops.

Pressure increases. The fuel starts to ignite and burn near the top dead center of the piston 01, and continues to burn until the first half of the subsequent downward stroke while increasing the pressure within the combustion chamber space 07. As the piston O1 moves downward, the pressure and temperature within the space 07 decrease, and after an intake and exhaust process, one cycle is completed. Through the above cycle, a part of the thermal energy of the fuel generated under high temperature and high pressure is extracted to the crankshaft 06 as mechanical energy.

However, the above method has the following drawbacks.

In the conventional piston, the trajectory of the reciprocating motion of the piston 01 relative to the rotation angle θ of the crankshaft 06 is determined geometrically by the crank arm radius and the length of the connecting rod 04. The robot moves in a manner similar to a sine wave.

Therefore, when the crankshaft 06 rotates at a constant rotational speed, its motion with respect to time is also the same, and as a result, the change in the volume within the combustion chamber space 07 with respect to time is as shown by the broken line in FIG. It is minimum at the top dead center TDC crank angle and maximum at the bottom dead center BDC crank angle. This is a simple change similar to a sine wave. Heat generation due to combustion occurring within the combustion chamber space 07 normally starts near the top dead center TDC and progresses in a roughly triangular shaped heat generation pattern until the middle of the expansion stroke, as shown in the lower part of Figure 5. However, especially in the latter half of combustion, it is called auxiliary combustion, and it is inevitable that the combustion speed will be slow.

On the other hand, as shown by the broken line in the upper part of Fig. 5, in the conventional combustion chamber, the rate of increase in the volume of the combustion chamber 07 increases uniformly after the top dead center until about the middle of the expansion stroke. A considerable portion of the heat generation by combustion, including the amount of heat generated by combustion, occurs in a state where the expansion of the volume has progressed considerably. the result.

This causes a decrease in the combustion cycle efficiency of internal combustion engines.

In order to avoid this, various improvements have been made to reduce the number of side effects and shorten the heat generation period, but no sufficient effect has been achieved.

In addition, in order to avoid the above-mentioned decrease in cycle efficiency, if the start of combustion is brought forward and the start time of heat generation is advanced, heat generation can be completed before expansion progresses, and cycle efficiency will be improved. In this case, the pressure of the working gas increases too much, leading to an increase in the maximum pressure.

The purpose of the present invention is to focus on the above point, and to reduce the speed of the downward movement of the sub-piston during the expansion stroke of the piston, thereby stopping the speed of expansion and thereby increasing the time until combustion is completed. This reduces the apparent aftereffects of heat generation, improves cycle efficiency by shortening the apparent combustion period, and ideally improves cycle efficiency without increasing the maximum pressure of the working gas. is to provide an internal combustion engine with low PmaX and high fuel consumption by drawing a cycle similar to the diesel cycle. Its features are a reciprocating mechanism consisting of a crankshaft, connecting rod, and piston pin, and a reciprocating mechanism that moves inside the cylinder liner. A reciprocating internal combustion engine having a reciprocating piston, a sub-piston provided to be able to reciprocate on a cylindrical sliding surface recessed in the piston, a cam provided at the upper part of the small end of the connecting rod, and the above-mentioned The present invention includes a sub-piston drive mechanism that causes the sub-piston to reciprocate relative to the piston by the cam which is interlocked with the swinging of the connecting rod around the piston.

The present invention is applicable to reciprocating internal combustion engines and compressors.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view showing a reciprocating internal combustion engine according to one embodiment of the present invention, and FIG. 3 is a sectional view showing a connecting rod.

In the figure, 01 to 7 in Fig. 1 indicate the conventional example.
and each are the same.

Reference numeral 10 denotes a sliding surface, which is recessed in the piston 1 in a cylindrical shape. Reference numeral 11 denotes an auxiliary piston, which is provided so as to be reciprocally movable so that its side surface slides on the sliding surface lO. A rod lla provided on the secondary piston 11 extends downward through the piston/crown.

12 is a spring, one end of which is connected to the bottom surface of piston 1.

The other end is provided so as to come into contact with a roller receiver 13 provided at the lower part of the sub-piston rod lla, and to press the sub-piston 11 downward.

Roller receiver 13. The roller 14 is provided below the sub-piston 11.

A cam 15 is formed at the small end of the connecting rod 4 along the outer periphery of the piston pin 3. When the connecting rod 4 swings around the piston pin 3 in the first half of the downward stroke of the piston 1, the cam surface pushes up the roller 14 and moves the sub-piston 11 upward.

The operation in the case of the above configuration will be described.

During the upward stroke of the piston, the connecting rod is tilted to the lower left in FIG. The space 7 is compressed in a conventional manner.

After top dead center TDC, piston 1 enters the downward stroke.

Since the connecting rod undergoes a rocking motion tilting downward to the right as shown in FIG. 2, the surface of the cam 15 comes into contact with the roller 14 and pushes the sub-piston 11 upward against the force of the spring 12. This situation is shown in FIG. 4 with the crankshaft 60 rotation angle as the horizontal axis. Following the cam lift after top dead center TDC, the sub-piston 11 moves upward as shown by the dashed-dotted line relative to the movement of the piston 1 (solid line), and as a result, the volume of the combustion chamber space 7 becomes equal to TDC as shown in the solid line. In between BDC and
A period occurs in which the rate of increase is reduced and the volume changes approximately to a constant volume over time.

After that, the inclination of connecting rod 4 reaches its maximum.

Similarly, the filj piston descends in accordance with the lift of the cam 15, and the sub piston 11 returns to the lowest position relative to the piston 1 by the bottom dead center BDC.

The rate of change dV/dθ of the combustion chamber space 7 at this time with respect to the crank angle (that is, with respect to time) is shown in FIG. Compared to the conventional one (dashed line), the combustion rate in the second half of the combustion stroke is slower and the heat generation rate dQ/dθ decreases.
V/dlj decreases, and the piston appears to stop for an hour.

As the rate of expansion of the combustion chamber space decreases in line with the decrease in the rate of heat release in the latter stages of combustion, the amount of additional heat generated, which would have led to a decrease in cycle efficiency in conventional systems, is more effectively converted into work. That will happen.

Furthermore, by setting the cam shape so that this dV/dθ changes in accordance with the change in the heat generation rate dQ/dθ, as is clear from the thermodynamic equation (1).

Here, if P is pressure, and specific heat ratio is Pdθ, then according to equation (1), pdP=o, that is, an ideal diesel cycle with almost no pressure rise during the combustion period can be drawn. It becomes possible.

The above case has the following effects.

(1) In the latter half of the combustion period, it is possible to effectively convert the slow heat generation that cannot be avoided by conventional addition into work.9. It is possible to improve the thermal efficiency of the internal combustion engine, that is, to achieve lower fuel consumption.

(2) Furthermore, by controlling the movement of the sub-piston by forming a cam so that the expansion velocity dV/dθ of the combustion chamber space changes in a constant relationship with the heat release rate dQ/dθ, an ideal It is possible to draw a cycle close to a diesel cycle, and it is possible to obtain performance with a low maximum pressure Pmax and low fuel consumption.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional reciprocating internal combustion engine. FIG. 2 is a sectional view showing a reciprocating internal combustion engine according to one embodiment of the present invention, and FIG. 3 is a sectional view showing a connecting rod. FIG. 4 is a diagram showing changes in the combustion chamber space volume and changes in the piston top surface position and sub-piston top surface position, and FIG. 5 is a diagram showing changes in the volume change rate and heat release rate. 1...Piston, 2...Cylinder liner, 3-'
・Piston pin, 4... connecting rod, 6... crankshaft. 10... Cylindrical sliding surface, 11... Sub-piston, 1
5...cam. Fang 3 Diary Spear 2 Crank standard θ proboscis 4th figure 5th figure

Claims (1)

[Claims] 1. A reciprocating internal combustion engine having a reciprocating mechanism consisting of a crankshaft, a connecting rod, and a piston pin, and a piston reciprocating within a cylinder liner. A sub-piston is provided to be able to reciprocate on a cylindrical sliding surface recessed in the piston, a cam is provided at the top of the small end of the connecting rod, and the connecting rod is linked to the swinging motion around the piston pin. A reciprocating internal combustion engine comprising a sub-piston drive mechanism that causes the cam to reciprocate the sub-piston relative to the piston.