JP3063496B2 - Piston crank mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston crank mechanism in which an output shaft makes one rotation via a connecting rod and a gear train in conjunction with reciprocation of a piston in an engine cylinder.

[0002]

2. Description of the Related Art In general, a piston-crank mechanism pins a piston between a reciprocating piston in a cylinder, a crankshaft as an output shaft, and a crankpin and a piston at a rotating end of a crank arm on the crankshaft. And a connecting rod connected thereto, and configured to convert a linear motion generated by the piston under pressure in the cylinder into a rotary motion of the crankshaft. An engine using such a piston crank mechanism incorporates an intake / exhaust mechanism, a fuel supply device, and the like into the engine to perform four strokes of suction, compression, combustion, and exhaust. The combustion gas is generated, the combustion energy is applied to the piston crank mechanism as a pressing force to the piston, and the pressing force (linear motion) of the combustion gas is output to the driven part side as the rotational movement of the crankshaft by the piston crank mechanism. it can.

[0003] In a diesel engine using such a piston crank mechanism, fuel is increased in pressure by a fuel injection pump driven by receiving a part of the driving force of the engine, and the fuel is sprayed into a combustion chamber by a fuel injection valve. Thus, combustion energy is generated in the combustion chamber. But,
In the case where the fuel is sprayed into the combustion chamber under the high-temperature and high-pressure atmosphere to cause compression ignition, the in-cylinder pressure and the in-cylinder combustion temperature are likely to increase rapidly as the ignition delay, which is a delay from the fuel spray to the ignition, advances. , prone to problems such as generation of noise and NO _X. Therefore, a pilot fuel injection method was adopted in which a small amount of fuel was injected into the combustion chamber prior to the main injection, and the pilot injection increased the ambient temperature in the combustion chamber,
It is known to improve ignitability during main injection. Furthermore, it is also done to promote atomization of fuel particles for of the NO _X reduction.

[0004]

However, in order to carry out the operation in the pilot injection mode, it is necessary to reliably execute the pilot injection and the main injection, which requires complicated opening / closing control means for the fuel injection valve. Furthermore, when promoting the atomization of fuel particles, the injection timing tends to be extended, and this causes the piston to start descending in the later stage of combustion, and the in-cylinder temperature,
There is a problem that the pressure is reduced, the combustion is not completely completed, and a large amount of so-called unburned residue such as black smoke and HC is discharged. Therefore, it is presumed that the piston can be held in a relatively wide crank angle displacement range near the compression top dead center position in response to a change in crank angle, but such a piston crank movement mechanism is not known. For example, in a piston crank movement mechanism disclosed in Japanese Patent Application Laid-Open No. 4-119212, a driven planetary gear is fixed to an eccentric shaft pivotally attached to a large end of a connecting rod, supported by a crank pin, and driven by a crank arm. Is provided to enable stepless displacement and phase displacement of the stroke length at any time. However, this adjusts the stroke or phase of the piston crank motion, and does not hold the piston in a relatively wide crank angle displacement range near the compression top dead center position.

An object of the present invention is to move a piston to a predetermined position,
In particular, it is an object of the present invention to provide a piston crank mechanism that can be held in a relatively wide crank angle displacement range near a compression top dead center position.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a planetary gear attached to an engine connecting rod, a primary gear meshing with the planetary gear and outputting power, and a primary gear meshing with the primary gear. An output shaft that outputs power to the clutch side, a ring gear that meshes with the planetary gear, and a ring gear that is driven in synchronization with the output shaft.
And a cam shaft for periodically rotating and displacing the gears at a predetermined timing . According to the present invention, the camshaft is driven at a rotation speed that is half that of the planetary gear .
It may be configured as follows. Further, according to the present invention, the ring gear may be rotated in the direction opposite to the revolving direction of the planetary gear by the cam shaft. Further, in the present invention, the timing of rotating the ring gear may be after the piston compression top dead center.

[0007]

[Function] A camshaft driven in synchronization with the output shaft provides a link.
Gears are periodically rotated and displaced at a predetermined timing,
Revolution of planetary gears meshed with gears
In this way, even if the rotation of the primary gear, that is, the rotation of the output shaft, is performed, the connecting rod and the piston on the planetary gear side are temporarily controlled to increase or decrease in displacement, and temporarily move to a predetermined position. Will be retained . When the camshaft is driven via the output shaft at half the rotational speed of the planetary gear, the same operation is performed. Furthermore, when the ring gear is rotated in the direction opposite to the revolving direction of the planetary gear by the camshaft, the rotation of the planetary gear in the revolving direction with respect to the rotation is temporarily reduced, and the rotation of the primary gear, that is, the rotation of the output shaft is performed. even, connecting rod and piston of the planetary gear side is increased or decreased restricted temporary displacement Resona
Is temporarily held at a predetermined position . Furthermore,
Assuming that the ring gear is rotated after the piston compression top dead center, the connecting rod and the piston on the planetary gear side are temporarily held near the compression top dead center.

[0008]

FIG. 1 shows a diesel engine (hereinafter simply referred to as an engine) equipped with a piston crank mechanism according to one embodiment of the present invention. The engine 1 is a multi-cylinder engine. Although FIG. 1 shows only the first cylinder, other cylinders have the same configuration. Combustion chamber 8 of engine 1
Is supplied with air from an intake / exhaust system (not shown) having a well-known structure, and exhaust gas is exhausted. Further, fuel is supplied from a fuel supply system described later, and a piston crank mechanism is attached to a piston 31 facing the combustion chamber 8. Are linked. As shown in FIGS. 1 and 2, the piston crank movement mechanism here is pin-connected to a piston 31 that reciprocates a set stroke S in each cylinder of a cylinder block 30 via a piston pin 32. A connecting rod 33, a planetary gear train G for transmitting the rotational movement of the other end 331 of the connecting rod 33 to the output shaft 34 as a rotational force, and a revolution adjusting means R for rotating a ring gear in the planetary gear train G by a fixed amount. Is provided.

As shown in FIGS. 2 and 3, the planetary gear train G includes a planetary gear 35 pivotally connected to a gear end 331 of a connecting rod 33 via a bearing (not shown), and the remaining two planetary gears on the planetary gear 35. A primary gear 37 that meshes with the three planetary gears 35, 36, and 36 from the inside and outputs power, an auxiliary gear 40 integrally connected to the primary gear 37 via a central shaft 42, and an auxiliary gear 40. An output gear 39 that meshes and transmits power to the clutch 38 via the output shaft 34, and meshes with the three planetary gears 35, 36, 36 from outside to form the cylinder block 3
And a ring gear 41 rotatably supported by a support frame (not shown) extending from 0. 3 planetary gears 3
The gears 5, 36, 36 are pivotally supported by carriers (not shown) at a constant relative interval, and are meshed with the ring gear 41 and the primary gear 37 so as to be relatively rotatable.

The output shaft 34 and the center shaft 42 are pivotally supported on the cylinder block 30 via bearings (not shown). Furthermore,
A cam gear 43 meshes with the output gear 39, and the cam gear 43
The camshaft 44 integral with the cylinder block 30 is pivotally supported on the cylinder block 30 side via a bearing (not shown). Here, when the piston 31 reciprocates through the set stroke S in the cylinder while the ring gear 41 is in a stationary state, the planetary gear train G is connected to the gear end 331 of the connecting rod 33 that is pin-connected to the piston 31.
Makes one revolution. One rotation of the gear end 331, that is, one rotation of the engine, is shifted according to the speed ratio in the planetary gear train G and transmitted to the auxiliary gear 40 side, and the speed ratio of the output gear 39 meshing with the auxiliary gear 40 is adjusted to both speed ratios. The output shaft 34
Rotates. Further, here, the rotational force is transmitted from the auxiliary gear 40 to the cam gear 43 via the output gear 39 at a reduced speed. Therefore, one revolution of the engine 1 is shifted by the total gear ratio of the three gears 40, 39, and 43 in addition to the gear ratio in the planetary gear train G, and here, it is set to 1/2 of the engine speed. Is set to the total gear ratio.

The revolution adjusting means R includes a ring gear 41 rotatably supported by a support frame (not shown) on the cylinder block side.
, A revolving adjustment cam 46 formed at one end of the camshaft 44 and slidingly in contact with a sliding end 451 at the other end of the push rod 45, and a revolving adjustment cam 46 The spring 47 which presses and urges the side
And Here, the cam shaft 44 of the revolution adjusting means R rotates half of the engine speed, and the revolution adjusting cam 46 on the cam shaft starts the lift immediately after the compression top dead center TDC at the crank angle, and sets the set angle. The push rod 45 is lifted in the revolution adjustment area a up to θc1, and the ring gear 41 is moved in the direction B opposite to the direction A of revolution of the planetary gear 35 corresponding to the lift amount h.
Rotate to. As a result, as shown in FIG. 4, in the revolution adjustment range a from the compression top dead center TDC to the set angle θc1, the piston position at normal time, that is, when the revolution adjusting means R is eliminated (in FIG. As shown by the solid line, the connecting rod 33 and the piston 31 can be held near the compression top dead center TDC for a longer time than usual, and then the piston 31 is lowered earlier than usual, and after the set angle θc1, The piston displacement of returning to the descending operation can be repeated.

Next, a fuel supply system provided in the engine 1 will be described. The fuel supply path 2 in the fuel supply system sends the fuel in the fuel tank 3 to the main path 5 by the fuel pump 4. Further, a plurality of branch paths 6 reaching each cylinder are branched from the main path 5, and the remaining fuel of each cylinder is guided to the low pressure path 7 side. Each branch 6 is provided with a unit injector 9 that can inject fuel toward the combustion chamber 8 of each cylinder. The unit injector 9 is electronically controlled,
An injector 10 for injecting fuel, a high-pressure pump unit 11 driven by a rotation transmission system 13 of the engine 1, and an electromagnetic valve 1
2 is provided in a single housing 901. Here, the solenoid valve 12 is connected to an engine control unit (hereinafter simply referred to as ECU) 14 via a driver 15, and keeps the high-pressure pump section 11 and the low-pressure path 7 in communication when off, and when on, the high-pressure pump section 11.
The high-pressure pump unit 11 is configured to inject fuel through the injector 10 by shutting off the pressure side and the low-pressure path 7.

The ECU 14 stores an engine speed N of the engine 1.
an engine rotation sensor 16 for outputting a e signal, a load sensor 17 for outputting a load signal theta _L substantial amount of depression of the accelerator pedal (not shown), a crank angle sensor for outputting a unit crank angle signal dθ and the reference signal θ0 of the engine 1 18 are connected. When the main switch is turned on, the ECU 14 starts driving the engine 1 of FIG. 1, and the unit injector 9 of each cylinder is driven by the rotation transmission system 13 of the engine 1, and the high-pressure fuel is supplied to the electromagnetic valve 12.
Pumped to the side. In this case, when the solenoid valve 12 reaches the predetermined injection timing θi immediately before the compression top dead center, the solenoid valve 12 receives the valve opening signal from the ECU 14 and opens, and the high pressure fuel is sprayed from the injector 10 into the combustion chamber 8 near the compression top dead center. Then, the fuel injection is stopped after the elapse of the Ti injection period.

At this time, the combustion chamber 8 which has received the fuel injection from the injector 10 reaches the vicinity of the compression top dead center, is in a high-temperature and high-pressure atmosphere, the self-ignited air-fuel mixture starts burning, and the in-cylinder pressure pm rapidly increases. I do. Further, at this time, as shown in FIG. 4, the revolution adjusting cam 46 starts lifting immediately after the compression top dead center TDC, and moves the ring gear 41 via the push rod 45 to the revolving direction A of the planetary gear 35 corresponding to the lift amount h. In the opposite direction B. In conjunction with this operation, the connecting rod and the piston on the planetary gear 35 side hold the piston 31 near the compression top dead center TDC longer than usual (see the broken line in FIG. 4), as shown by the solid lines in FIG. it can. As a result, the in-cylinder pressure and temperature of the combustion chamber 8 are maintained at a high pressure and a high temperature for a longer period than usual, and the combustion is reliably promoted even in the later stage of the combustion, and the combustion is relatively completely achieved.
The unburned residue such as black smoke and HC in the exhaust gas is reduced.

In the above description, the fuel injection valve is the unit injector 9, but instead, an injector connected to a row-type or distribution-type fuel injection pump may be used. Obtainable. Further, the revolution adjusting means R of FIG. 1 reduces the moving speed of the piston in the revolution adjusting area a after passing through the compression top dead center position, but in other crank angle displacement areas, for example, immediately before the compression top dead center position. The revolution adjusting means R is configured to rotate the ring gear 41 in the same direction as the revolving direction A in the operating range, whereby the piston is quickly moved to the vicinity of the compression top dead center TDC at the compression top dead center position. Compress piston at top dead center TD
It may be held relatively long near C. The piston crank mechanism in this case can be effectively used for an engine that performs pilot injection prior to the well-known main injection, and can maintain the in-cylinder pressure and temperature of the combustion chamber 8 at the time of pilot injection higher and higher than usual, and the pilot injected fuel can be used. There is an advantage that the combustion of the fuel can be surely promoted.

[0016]

As described above, the drive is synchronized with the output shaft.
By a cam shaft which rotates the ring gear, temporarily increasing or decreasing adjusts the rotation of the revolving direction relative to the rotation of the planetary gears, to increase or decrease adjusts the displacement of the planetary gear side of the connecting rod and the piston, temporarily holds the piston in place Can
I can do it .

In particular, if the camshaft is driven via the output shaft at a rotation speed of 1/2 of the planetary gear, the same effect can be obtained. In particular, when the ring gear is rotated in the direction opposite to the revolving direction of the planetary gear by the camshaft, the connecting rod and the piston on the planetary gear side are temporarily reduced, and the same effect is obtained. In particular, if the time to rotate the ring gear is after the piston top dead center, the connecting rod and the piston on the planetary gear side are temporarily held near the compression top dead center, and the in-cylinder pressure and temperature of the combustion chamber are longer than usual. High pressure and high temperature can be maintained for a period, combustion can be reliably promoted even in the later stage of combustion, combustion is relatively completely achieved, and it is easy to reduce unburned residue such as black smoke and HC in exhaust gas.

[Brief description of the drawings]

FIG. 1 is a schematic overall configuration diagram of a piston crank mechanism of the present invention.

FIG. 2 is an enlarged side view of a main part of a piston crank movement mechanism in the apparatus of FIG. 1;

FIG. 3 is a partially cut-away enlarged side view of a part of a gear train in a piston crank movement mechanism in the apparatus of FIG. 1;

4 is a piston position characteristic diagram of an engine including the piston crank movement mechanism of FIG. 1. FIG.

FIG. 5 is an in-cylinder pressure diagram of an engine equipped with the piston crank movement mechanism of FIG. 1;

[Explanation of symbols]

 1 Engine 8 Combustion Chamber 33 Connecting Rod 34 Output Shaft 35 Planetary Gear 37 Primary Gear 38 Clutch 41 Ring Gear 44 Camshaft

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16H 21/16-21/38

Claims (4)

(57) [Claims] 1. A planetary gear mounted on a connecting rod of an engine, a primary gear meshing with the planetary gear and outputting power, an output shaft meshing with the primary gear and outputting power to a clutch side, meshing with the planetary gear. A ring gear, driven in synchronization with the output shaft, and
A piston crank mechanism comprising: a camshaft that periodically rotates and displaces by rotating . 2. The piston crank mechanism according to claim 1, wherein said camshaft is driven at a rotation speed of one half of said planetary gear. 3. The piston crank mechanism according to claim 1, wherein said ring gear is rotated in a direction opposite to a revolving direction of said planetary gear by said cam shaft. 4. The piston crank mechanism according to claim 1, wherein the timing of rotating the ring gear is after the piston compression top dead center.