WO1995018294A1

WO1995018294A1 - Miller cycle engine

Info

Publication number: WO1995018294A1
Application number: PCT/JP1994/002215
Authority: WO
Inventors: Takeshi Ishihara; Godou Ozawa
Original assignee: Komatsu Ltd.
Priority date: 1993-12-28
Filing date: 1994-12-26
Publication date: 1995-07-06
Also published as: DE4480333T1; GB9613353D0; GB2300226A

Abstract

A miller cycle engine which is simple in construction, and provides a low compression ratio and a high expansion ratio, thereby making it possible not only to improve the thermal efficiency and exhaust emissions of the engine but also to clean exhaust gas and prevent an increase in blow-bye amount. To this end, a volume chamber (8) communicating with a cylinder chamber (4) at a position a predetermined distance (Ha) above the bottom dead center of the stroke of a piston (2) is provided, and the volume chamber (8) refrains a pressure increase in the cylinder chamber (4) at the beginning of a compression stroke. In addition, a pressure piston ring (32) is disposed at the skirt portion of piston (10) for preventing fresh air and exhaust gas accumulating in said volume chamber (8) from leaking into a crank case (13).

Description

Technical Description Mirror Cycle Engine Technology

The present invention relates to a mirror cycle engine, and more particularly to a mirror cycle engine provided with a volume chamber communicating with a cylinder chamber. Background technology

Conventionally, for a mirror cycle engine, a method of closing the intake valve early (for example, see Japanese Patent Application Laid-Open No. 55-148932) and a method of closing the intake valve late ( For example, Japanese Patent Application Laid-Open No. 2-123234 is disclosed. The method of closing the intake valve as shown in the acupressure diagram in Fig. 11 is as follows: intake stroke (between a-b-c), compression stroke (between c-b-d), expansion stroke (e-f ) And the exhaust stroke (between g-b-a), the intake valve is closed early during the intake stroke, and the latter half of the intake stroke (between bc) is expanded.

In addition, the method of closing the intake valve late as shown in FIG. 12 is as follows: the intake stroke (between h, i, and j), the compression stroke (between j, i, and k), the expansion stroke (between m and n), During the intake stroke, the intake valve is closed late during the intake stroke, and the intake pressure is released early in the compression stroke (between j and i). In this late closing method, the intake valve is opened during the compression stroke to provide a stroke without compression, and as the piston rises, a part of the intake air is taken into the intake manifold. To reduce the compression ratio substantially. In addition, in this method, it is known that a screw-type compressor is used on the intake side to supply sufficient air into the cylinder chamber, from which the air flows back to the intake manifold. ing.

However, in the conventional mirror cycle engine described above, the intake valve is closed early or late by using a variable valve timing device, or the rotary valve is closed. They were closed early using a blast device, but both had problems with complicated structures and poor durability. Disclosure of the invention

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned drawbacks of the related art, and has as its object to provide an inexpensive mirror cycle engine with a simple structure in which a volume chamber communicating with a cylinder chamber is simply provided. Aim.

The mirror cycle engine according to the present invention is provided with a volume chamber communicating with the cylinder chamber at a predetermined position above the bottom dead center of the stroke of the piston. It is characterized by suppressing the pressure rise in the cylinder chamber. An on-off valve may be provided in a passage connecting the cylinder chamber and the volume chamber. Moreover, a controller connected to the on-off valve may be provided, and the controller may control opening and closing of the on-off valve. Further, the volume of the volume chamber may be variable. The volume chamber may be provided with a variable mechanism such as a solenoid, a piston or an actuator, and the variable mechanism may make the volume of the volume chamber variable. Moreover, a controller connected to the variable mechanism may be provided, and the controller may control the volume of the volume chamber. In addition, an engine rotation sensor connected to the controller and a rack position detection sensor for the engine fuel injection pump are provided, so that the measured engine speed and rack position can be input to the controller. Good. In the above configuration, a pressure screw ring is disposed on the piston scar section, and this pressure screw ring is used to collect fresh air accumulated in the volume chamber in the early stage of the compression stroke and the volume of the fresh air in the early stage of the exhaust stroke. It may be possible to prevent the exhaust gas accumulated in the chamber from leaking into the crankcase.

According to this configuration, by providing the volume chamber communicating with the cylinder chamber, the pressure rise in the cylinder chamber is suppressed to be low by using the volume of the volume chamber at the beginning of the compression stroke. Moreover, when the piston rises by a predetermined stroke, the hole in the cylinder chamber communicating with the volume chamber is closed, and the pressure in the cylinder chamber is raised to a predetermined value. Therefore, the predetermined pressure is set to a low value because the volume chamber suppresses the pressure rise. It is possible to reduce the compression ratio substantially. As a result, all of the air drawn into the cylinder chamber can be utilized with a simple structure, and the engine output can be obtained with a low compression ratio and a high expansion ratio corresponding to the cylinder volume. Can be improved. In addition, by making the volume chamber variable, it is possible to control the mirror cycle according to the engine speed, and to obtain higher output.

In addition, since the pressure screw ring is provided in the bis-trans-cart section, fresh air accumulated in the volume chamber in the early stage of the compression stroke does not leak to the crankcase, and a sufficient amount of fresh air in the later stage of the expansion stroke. Jets into the cylinder chamber and stirs the combustion gas to promote oxidation. This purifies the exhaust gas and prevents fresh air and exhaust gas from leaking into the crankcase, thereby preventing an increase in the amount of blow-by.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a conceptual diagram of a main part of a mirror cycle engine according to a first embodiment of the present invention, FIG. 2 is a shiatsu diagram of a four-cycle diesel engine of a mirror one-cycle engine according to the present invention,

FIG. 3 is a conceptual diagram of a main part of a mirror cycle engine according to a second embodiment of the present invention, and FIG. 4 is a table showing a relationship between an engine speed R and an average effective pressure P me in the second embodiment.

FIG. 5 is a conceptual diagram of a main part of a mirror cycle engine according to a third embodiment of the present invention, and FIG. 6 is a diagram illustrating an engine speed R (rpm), an average effective pressure P me, and a critical maximum explosion pressure in the third embodiment. A chart showing the relationship of P max,

FIG. 7 is a conceptual diagram of a principal part of a mirror cycle engine according to a fourth embodiment of the present invention at the top dead center of the piston.

Fig. 8 is a conceptual diagram of the essential parts at the bottom dead center of the piston of the mirror cycle engine according to the fourth embodiment.

FIG. 9 is a conceptual diagram showing the initial state of the compression stroke according to the fourth embodiment, FIG. 10 is a conceptual diagram showing a state in a later stage of the expansion stroke according to the fourth embodiment, and FIG. 11 is an acupressure diagram of a 4-cycle diesel engine of a conventional technology, in which the intake valve of a mirror cycle engine is rapidly closed.

Fig. 12 is an acupressure diagram of a four-cycle diesel engine with slow closing of the intake valve of a mirror cycle engine according to the prior art. BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the mirror cycle engine according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a conceptual diagram of a part of a mirror cycle engine according to a first embodiment of the present invention. In FIG. 1, a piston 2 is pivotally inserted into a cylinder liner 11, and a predetermined stroke S moves up and down by rotation of a crankshaft (not shown). An engine head 3 is disposed at an upper end of the cylinder liner 11, and a cylinder chamber 4 is formed by the piston 2 and the engine head 3. The engine head 3 is provided with an intake pipe 3a and an exhaust pipe 3b. A mushroom-shaped intake valve 5 is provided at a communication port of the intake pipe 3a with the cylinder chamber 4, and an exhaust pipe 3b. There are 6 mushroom-shaped exhaust valves at the communication port with the cylinder room 4 of each, which are provided respectively. A communication hole 7 is formed at a predetermined position of the cylinder liner 1, that is, at a position above a lower dead center of the lower end of the predetermined stroke S of the piston 2, and a predetermined hole is formed in the communication hole 7. Volume room 8 is provided.

The operation of the above configuration will be described with reference to FIG. 2 showing a four-cycle digital pressure diagram of the present invention. Figure 2 shows the intake stroke (between L1 and L2), the compression stroke (between L2 and L3 and L4), the expansion stroke (between L5 and L6), and the exhaust stroke (between L2 and L1). In the compression stroke, the intake valve 5 is closed, and at the beginning of the compression stroke (between L 2 and L 3), the pressure rise is suppressed low by using the volume of the volume chamber 8.

In other words, as shown in Fig. 1, it changes depending on the rotation angle の of the crankshaft. Assuming that Vs (室) is the stroke volume of the cylinder chamber 4 and Vd is the volume of the volume chamber 8, the upper end surface 2a of the piston 2 is a communication hole from the start of compression. In the initial stage of the compression stroke (distance H a) until the upper end face 7 a of the cylinder 7 is closed, the stroke volume V of the cylinder is calculated by adding the stroke volume V s (Θ) and the volume V d of the volume chamber 8. It is a thing. Next, after the upper end surface 2a of the piston 2 closes the upper end surface 7a of the communication hole 7, the piston 2 rises further in the compression stroke (hereinafter referred to as the latter half of the compression stroke). The cylinder stroke—the volume V is only the stroke volume V s (Θ) of the cylinder chamber 4.

Therefore, assuming that the product of the pressure P of the cylinder chamber 4 and the stroke volume V of the cylinder in the compression stroke is constant, the stroke volume V of the cylinder (= Vs (Θ) + Vd) is at the beginning of the compression stroke. Since it is large, the change rate of the pressure P can be made smaller than the change rate of the stroke volume V of the cylinder. As a result, the pressure rise can be kept low (between L 2 and L 3). On the other hand, in the latter half of the compression stroke, the stroke volume V (= V s (Θ)) of the cylinder is small, so that the rate of change of the pressure P can be increased relative to the rate of change of the stroke volume V of the cylinder. Therefore, the pressure rise becomes large (between L 3 and L 4), and a sufficient compression pressure Pa can be obtained. In such a stroke, the air sucked into the cylinder chamber 4 does not escape to the intake side and does not expand by closing the intake valve 5 early. Therefore, fresh air accumulated in the volume chamber 8 in the early stage of the compression stroke is ejected from the volume chamber 8 to the cylinder chamber 4 in the late stage of the expansion stroke, agitating the combustion gas, promoting oxidation of the combustion gas, and exhaust gas. Useful for purification. Further, since the compression pressure Pa of the present embodiment is low similarly to the conventional compression pressure Po shown in FIG. 11, a low compression ratio can be obtained. In this case, a low compression ratio and a high expansion ratio can be obtained, and the thermal efficiency and exhaust emission of the engine can be improved.

Next, a second embodiment of the mirror cycle engine of the present invention will be described with reference to the drawings. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 3 shows a main part of the engine of the present embodiment, in which a cylinder chamber 4 and a volume chamber 8 are connected. An electromagnetic valve 12 (open / close valve) that opens and closes is disposed in the communication passage 11. This electromagnetic valve 12 is connected to a controller 13. The controller 13 has an engine rotation sensor 14 attached to a crankshaft (not shown) for measuring the engine rotation speed, and a rack position of an injection pump for injecting fuel into the cylinder chamber 4. The rack position detection sensor 15 for detecting is connected.

The operation of the above configuration will be described with reference to the relationship between the engine speed R (rpm) and the average effective pressure Pme shown in FIG. 4 and FIG. The rack position of the fuel injection pump is set by a command from an accelerator petal or the like (not shown), and the rack position detection sensor 15 detects this rack position. The engine speed is measured by the engine speed sensor 14. The signals from the rack position detection sensor 15 and the engine rotation sensor 14 are sent to the controller 13, and the controller 13 calculates the average effective pressure P m e from both signals. When the calculated average effective pressure P m e is equal to or less than a predetermined value, a command signal is output to close the electromagnetic valve 12. As a result, when the engine load is low, the engine is driven by a normal engine, and when the engine load is high, the engine becomes a mirror cycle engine, and a low compression ratio and a high expansion ratio are obtained, thereby improving the thermal efficiency of the engine.

Next, a third embodiment of the mirror cycle engine of the present invention will be described with reference to the drawings. The same parts as those in the above embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 5 shows a main part of the engine of the present embodiment. A variable volume volume chamber 20 is provided in a communication hole 7 formed at a predetermined position of the cylinder liner 11. This volume chamber 20 is composed of a cylinder 21, a piston 22 that is pivotally inserted into the cylinder 21, and a solenoid 23 that moves the piston 22. ing. The controller 25 connected to this solenoid 23 has an engine rotation sensor 14 that measures the engine speed and a rack position detection that detects the rack position of the injection pump. Sensor 15 is connected.

The operation in the above configuration will be described with reference to FIGS. High engine output To achieve high supercharging by turbocharger

However, the maximum explosion pressure P max of the conventional mirror cycle is limited by the output indicated by the one-dot chain line in the figure. In the present embodiment, when the output limit is equivalent to the dashed-dotted line Pmax, for example, when the piston 22 is at an intermediate position W having a predetermined volume, the average effective pressure Pme is represented by a solid curve. Become. Further, when the engine requires a low compression ratio and a high expansion ratio to improve the thermal efficiency of the engine, the piston 22 is moved to the position V of FIG. 5 having a larger predetermined volume. Retreat. As a result, the Pme that can be output at the same Pmax can rise to the position indicated by the dotted curve.

In the above description, the case where the output is changed by retracting the piston 22 is described.However, the position where the piston 22 is moved forward most and the volume chamber 20 having a variable volume is set to zero volume, that is, By setting it to position Y in Fig. 5, it can be used as a normal engine. This control is performed in the same manner as in the second embodiment. The position of the rack of the fuel injection pump and the rotation speed of the engine are sent to the controller 25, and the controller 25 receives the average effective pressure p from both signals. Calculate _me . When the calculated average effective pressure P me is equal to or lower than a predetermined value, the piston 22 is advanced to the maximum position to make the volume of the volume chamber 20 zero. Thus, when the engine load is low, the engine is driven by a normal engine, and when the engine load is high, the piston 22 is retracted to become a mirror cycle engine, and the low compression ratio and high expansion ratio are reduced. As a result, the thermal efficiency of the engine can be improved. As described above, a mirror cycle engine can be obtained with a simple structure.

In the above embodiment, the control of the on-off valve 12 and the variable-volume volume chamber 20 was performed using an electromagnetic solenoid, but the actuator, control valve, etc. were controlled by hydraulic pressure, pneumatic pressure, etc. A variable mechanism may be used.

Next, a fourth embodiment of the mirror cycle engine of the present invention will be described with reference to the drawings. The same parts as those in the above embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 7 shows the state of the top dead center position of the biston in the mirror cycle engine of the present embodiment. In the cylinder liner 1 integrated with the crankcase 33, the piston 10 is pivotally connected. Has been inserted. The piston 10 has a pressure piston ring 31 mounted on the upper part and a pressure screw ring 32 mounted on the skirt. When the piston 10 is at the top dead center position, the pressure screw ring 32 of the scart portion is located below the lower end face 7 b of the communication hole 7.

Fig. 8 shows the case where piston 10 is at the bottom dead center position, and piston 10 slides up and down by a predetermined stroke S up and down due to rotation of a crankshaft (not shown). You. In addition, at the bottom dead center position, the upper end face 10a of the piston 10 is located below the lower end face 7b of the communication hole 7, and the distance from the upper end face 7a is the same as in the first embodiment. Ha.

The Shiatsu diagram for the four-cycle operation of the diesel engine with this configuration is basically the same as the Shiatsu diagram of the first embodiment (FIG. 2), and a description thereof will be omitted. Next, the operation of the piston ring 32 different from the first embodiment will be described. As shown in Fig. 9, in the initial stage of the compression stroke of piston 10, fresh air sucked into cylinder chamber 4 rises from the top dead center 10a of piston 10 from bottom dead center. It is stored in the volume chamber 8 as indicated by the solid arrow until it passes the upper end face 7a of the communication hole 7.

Then, the piston 10 rises and compresses, and then the fuel burns and expands to a later stage of the expansion stroke, and the upper end face 10 a of the piston 10 becomes the upper end face 7 a of the communication hole 7. After that, as shown in FIG. 10, the fresh air confined in the volume chamber 8 is blown out into the cylinder chamber 4 as indicated by an arrow, and the combustion gas is stirred to promote oxidation and exhaust. It contributes to gas purification. During this time, the volume chamber 8 and the crankcase 33 are shut off by the pressure piston ring 32, as shown in FIG. 7, so that fresh air in the volume chamber 8 does not leak. Therefore, a sufficient amount of fresh air is ejected into the cylinder chamber 4 in the latter half of the expansion stroke. In addition, since the fresh air and the exhaust gas accumulated in the volume chamber 8 at the beginning of the exhaust stroke do not leak to the crankcase 33, a mirror cycle engine capable of preventing an increase in the provision amount can be obtained. .

Industrial applicability The explanation is that the simple structure of providing a volume chamber that communicates with the cylinder chamber achieves a low compression ratio and a high expansion ratio to improve the thermal efficiency of the engine and the emission of exhaust gas. By preventing exhaust gas from leaking, it is useful as a mirror cycle engine that can purify exhaust gas and prevent an increase in blow-by volume.

Claims

The scope of the claims

1. In a mirror cycle engine that includes a piston and a cylinder chamber in contact with the piston, and suppresses a pressure increase in the cylinder chamber, a lower dead center of a stroke of the piston is provided. A mirror cycle engine, wherein a volume chamber communicating with the cylinder chamber is provided at a predetermined upper position, and the volume chamber suppresses a pressure increase in the cylinder chamber at an early stage of a compression stroke.

2. The mirror cycle engine according to claim 1, wherein an on-off valve is provided in a passage communicating the cylinder chamber and the volume chamber.

3. The mirror cycle engine according to claim 2, further comprising a controller connected to the on-off valve, wherein the controller controls opening and closing of the on-off valve.

4. The mirror cycle engine according to claim 1, wherein the volume of the volume chamber is variable.

5. The volume chamber is provided with a variable mechanism such as a solenoid, a piston, or an actuator, and the variable mechanism makes the volume of the volume chamber variable. The mirror cycle engine according to range 4.

6. The mirror cycle engine according to claim 5, further comprising a controller connected to the variable mechanism, wherein the controller controls a volume of the volume chamber.

7. The engine rotation sensor and engine fuel injection pump connected to the controller 7. The micom according to claim 3, further comprising: a rack position detecting sensor for the pump, wherein the measured engine speed and the rack position are input to the controller. La Sai Klujing.

8. A pressure piston ring is provided on the scart portion of the piston, and the pressure screw ring is used for the fresh air accumulated in the volume chamber in the early stage of the compression stroke and the pressure piston ring in the early stage of the exhaust stroke. The mirror cycle engine according to any one of claims 1 to 7, wherein leakage of the exhaust gas accumulated in the volume chamber into the crankcase is prevented.