CN105508046A - Piston with variable compression ratio - Google Patents

Abstract

The invention discloses a variable compression ratio piston, which comprises a piston upper body, a piston lower body, a locking pin, a reed and a motor driving device, and is characterized in that: the motor stator is fixed on the motor base at the center of the inner sleeve; the inner sleeve passes through The boss is connected with the lower body of the piston and fixed under the constraint of the snap ring; there is a fixed round wheel structure at the upper end of the motor rotor, and there is a connecting device around the round wheel structure to connect the tail end of the reed; the outer periphery of the inner sleeve is another circle of cylindrical There are four pin holes on the upper part of the pin seat to install the locking pin. The pin head of the locking pin is a crescent structure and matches the locking groove on the inner wall of the piston upper body. The pin tail of the locking pin and the reed The first ends of the springs are connected through connecting holes; the spring is installed between the pin hole of the locking pin and the pin hole of the inner sleeve, and plays a role in returning the locking pin. The invention has few parts and simple structure, and changes the compression ratio of the engine instantaneously through the traction effect of the motor, so that the engine has good power performance and fuel economy under different working conditions.

Description

A variable compression ratio piston

technical field

The invention belongs to an automobile engine piston, more specifically a variable compression ratio piston.

Background technique

The compression ratio is the ratio of the maximum volume of the cylinder at the bottom dead center to the minimum volume of the cylinder at the top dead center. If the compression ratio is large, the pressure and temperature of the mixture at the end of compression will be higher, and the combustion rate will be faster, so the combustion efficiency of the engine will increase. It will get better, but the compression ratio of the engine should not be too high, because for gasoline engines, if the compression ratio is high, knocking will occur. In order to reduce the impact of knocking on the engine, this problem appears in the design of supercharged engines. particularly prominent. Fixed compression ratio becomes a very important factor restricting supercharged and turbocharged engines. We know that when turbocharging is involved, the temperature and pressure of the combustion chamber will increase significantly. If this value is too high, knocking will be inevitable. This can cause massive damage to the engine, as well as affect power delivery. Therefore, turbocharged and supercharged engines with a fixed compression ratio can only be designed to have a much lower compression ratio than ordinary naturally aspirated engines. However, this low compression ratio design will cause the engine to have very low combustion efficiency, especially when the turbocharger is not fully involved, and the power it can generate is much less than that generated by an ordinary naturally aspirated engine. This contradiction is an important reason for designers to develop variable compression ratio engines.

The purpose of variable compression ratio is to improve the fuel economy of a supercharged engine. In a supercharged engine, in order to prevent knocking, its compression ratio is lower than that of a naturally aspirated engine. When the boost pressure is low, the thermal efficiency is reduced. The fuel economy is reduced. Especially in the turbocharged engine, due to the slow rise of the boost degree, the torque rise is also very slow under the condition of low compression ratio, forming the so-called boost lag phenomenon. That is to say, when the engine is at a low speed, the supercharging effect lags behind. The supercharging system will not work until the engine accelerates to a certain speed. In order to solve this problem, variable compression ratio is an important method. That is to say. In the low load condition with low supercharging pressure, the compression ratio is increased to be the same as or higher than that of the naturally aspirated engine; on the other hand, the compression ratio is appropriately reduced under the high boost and high load condition. In other words, the compression ratio is continuously adjusted as the load changes, so that the thermal efficiency can be improved from low load to high operating conditions.

The compression ratio of a general engine cannot be changed, because the volume of the combustion chamber and the working volume of the cylinder are fixed parameters, which have been determined in the design. However, in order to make modern engines more efficient in various changing working conditions, designers add some mechanical components to make the engine change the compression ratio of the engine through the control of the ECU during operation.

However, there are several problems with current variable compression ratio engine technology. It mainly includes a large number of complex changes to the cylinder head, which greatly increases the manufacturing cost, and the addition of a large number of complex mechanical components reduces the reliability and increases the cost. In addition, the realization of the variable compression ratio technology must have two The components move relative to each other, so the sealing problem is the key issue that leads to the realization of variable compression. The above problems lead to the limitation of variable compression ratio technology.

Contents of the invention

The technical problem to be solved by the present invention is to provide a variable compression ratio piston for the above problems, which can change the engine compression ratio by changing the relative position between the piston top and the connecting rod so that the engine has good performance under different load conditions. power and fuel economy.

In order to solve the problems of the technologies described above, the present invention is achieved by adopting the following technical solutions:

A piston with a variable compression ratio, comprising a piston upper body, a piston lower body, a locking pin, a spring, a reed and a motor drive device, is characterized in that:

The stator of the motor is fixed on the motor seat in the center of the inner sleeve, the inner sleeve is fixed on the lower body of the piston through a snap ring, and the spring is installed between the groove of the locking pin and the pin hole of the inner sleeve, and the inner sleeve is connected with the lower body of the piston. The upper end of the rotor has a fixed round wheel structure, and there is a connecting device around the round wheel structure to connect the tail end of the reed. The head end of the reed pulls the pin tail of the locking pin, and the inner sleeve is connected with the lower body of the piston and is restrained by the snap ring. Fixed, the upper body of the piston is connected with the lower body of the piston through a guide plate.

The outer periphery of the inner sleeve is another circle of cylindrical pin seat. There are four evenly distributed pin holes on the upper part of the pin seat. Locking groove cooperates, and the pin tail of locking pin is that the head end of rod-shaped structure is connected with the reed by connecting hole, and the seat bottom of inner cover has four evenly distributed bosses.

There are four evenly distributed guide holes on the subsection of the upper body of the piston, and there are two upper and lower locking grooves with trapezoidal cross-sections on the inner wall of the upper body of the piston.

The section of the lower body of the piston is cast with four evenly distributed guide plates inserted into the four evenly distributed guide holes corresponding to the upper body of the piston, and there are four frustum-shaped concave holes on the bottom surface of the lower body of the piston.

The reed is an elastic metal structure with connecting devices at the head and tail.

Compared with prior art, the beneficial effects of the present invention are:

1. The use of motor drive makes the mechanical movement more reliable.

2. The inertial force of the piston and the pressure of the working fluid in the cylinder are used to promote the separation and combination of the pistons, which greatly reduces the driving power of the motor, making it possible to install a control strategy of a motor device inside the piston.

3. Since the change is only carried out in the piston body, and does not involve changes to the cylinder head or even the whole engine, the invention has good manufacturability.

4. The cost of the invention is low because the number of additional mechanical parts is small, and some parts belong to standard parts and mature matching parts in the market.

5. Since the rotor of the motor is connected with the locking pin by the reed, the reed acts as a buffer, so that the present invention does not require too high precision of the motor.

The relative disadvantage of the present invention is that it can only be used for a two-stage variable compression ratio and cannot be used for an infinitely variable compression ratio engine.

Description of drawings

Accompanying drawing 1 is the main sectional view of piston assembly.

Accompanying drawing 2 is the oblique view of piston interior.

Accompanying drawing 3 is the main sectional view of motor seat parts.

Accompanying drawing 4 is the A-A projection view of the main section of motor seat parts.

Accompanying drawing 5 is the front view of locking pin.

Accompanying drawing 6 is the top view of locking pin.

Among the figure: piston upper body 1, locking pin 2, inner sleeve 3, snap ring 4, reed 5, spring 6, motor (motor rotor 7, motor stator 8), piston lower body 9.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figures 1 and 2, the entire piston is divided into two parts: the upper piston body 1 and the lower piston body 9. There are four fan-shaped guide holes around the bottom surface of the piston upper body 1, and there are two trapezoidal locking grooves on the inner wall. There are four fan-shaped guide plates on the top surface corresponding to the guide holes of the piston upper body 1, and the base is cast with four conical concave holes.

As shown in Figures 5 and 6, the locking pin 2 is a cylindrical part, and the front is cast with a trapezoidal cross-section arc-shaped pin head that matches the inner wall of the piston upper body 1 with two trapezoidal locking grooves. The stick-shaped pin tail is used to connect the reed 5.

As shown in Figures 3 and 4, the bottom of the inner sleeve 3 has four conical bosses that cooperate with the four conical concave holes of the lower piston body 9 to limit the rotation of the inner sleeve 3 around the axis. The center of the inner sleeve 3 is a cylinder The shaped motor seat is used to fix the motor stator 8, and the outer periphery of the inner sleeve 3 is another cylindrical pin seat, and there are four pin holes on the upper part of the pin seat to install the locking pin 2 and the spring 6.

The snap ring 4 is a steel structure formed by circular arcs whose inner and outer circle centers do not overlap, and has a certain degree of elasticity, which is used to prevent the displacement of the inner sleeve 3 and play a role of retention and stability.

As shown in Figure 2, the reed 5 is composed of four elastic steel sheets, which play the role of buffering and pulling the pin tail of the locking pin 2. There are connecting holes at the head and tail of the reed 5, and the first end is connected to the pin tail of the locking pin 2. The tail end is connected with the motor rotor 7.

As shown in Figures 1 and 2, the motor is divided into a motor stator 8 and a motor rotor 7. The motor stator 8 is fixed on the inner sleeve 3, and the motor rotor 7 rotates. The upper end of the motor rotor 7 has a fixed round wheel structure, and there are four round wheel structures around it. The connecting device is used to connect the reed 6.

The spring 6 is installed between the pin hole of the locking pin 2 and the pin hole of the inner sleeve 3, and plays the role of returning the locking pin 2.

If the engine needs a low compression ratio, during the air intake process, the connecting rod pulls the piston so that the piston moves from the top dead center to the bottom dead center, and the pin head of the locking pin 2 is in the lower locking groove of the upper body 1 of the piston. At this time, the gas pressure in the cylinder is very small and close to atmospheric pressure, so it is negligible. When the piston is close to the bottom dead center, the motor rotor 7 rotates at this time, which drives the reed 5 to tighten, and the reed 5 tightens the locking pin 2 and the piston upper body 1. The lower locking groove of the piston is separated and the spring 6 is in a compressed state. At this time, there is no connection between the upper piston body 1 and the lower piston body 9. At the bottom dead center, the lower piston body 9 moves in the opposite direction due to the action of the connecting rod, and the piston The upper body 1 moves in the original direction due to the inertial force, so the relative distance between the piston upper body 1 and the piston lower body 9 decreases. When the upper locking groove of the piston upper body 1 is just aligned with the locking pin 2, the motor stops Work, now the pin head of locking pin 2 is inserted in the upper locking groove under the effect of compression spring 6, and now the engine runs under the low compression ratio working condition.

If the engine needs a high compression ratio, during the exhaust process, the connecting rod pulls the piston so that the piston moves from the bottom dead center to the top dead center, and the pin head of the locking pin 2 is in the upper locking groove of the upper body 1 of the piston. The gas pressure in the cylinder is slightly higher than the atmospheric pressure, so it is negligible. When the piston is close to the top dead center, the motor rotor 7 rotates at this time, which drives the reed 5 to tighten, and the reed 5 tightens the steel wire so that the locking pin 2 and the upper body of the piston 1 The upper locking groove is separated and the spring 6 is in a compressed state. At this time, there is no connection between the upper piston body 1 and the lower piston body 9. At the top dead center, the lower piston body 9 moves in the opposite direction due to the action of the connecting rod. The upper piston body 1 moves in the original direction due to the action of inertial force, so the relative distance between the upper piston body 1 and the lower piston body 9 increases. When the lower locking groove of the upper piston body 1 is just aligned with the locking pin 2, the motor Stop working, and now the pin head of locking pin 2 is inserted in the locking groove under the effect of compression spring 6, and now the engine runs under high compression ratio working conditions.

Claims (5)

1. the invention discloses a kind of variable-compression-ratio piston, comprise piston upper body (1), piston lower body (9), lock pin (2), spring (6), reed (5) and motor drive unit, it is characterized in that: described motor stator (8) is fixed on the motor cabinet at inner sleeve (3) center, inner sleeve (3) is fixed on piston lower body (9) by snap ring (4), spring (6) is arranged on rotor (7) upper end that is connected with piston lower body (9) of inner sleeve (3) between the groove of lock pin (2) and the pin-and-hole of inner sleeve (3) fixing round wheel construction, connection set is had to be used for connecting reed (5) tail end around circle wheel construction, the pin tail of the head end traction lock shotpin (2) of reed (5), inner sleeve (3) is connected with piston lower body (9) and fixes under the constraint of snap ring (4), piston upper body (1) is connected by guide plate with piston lower body (9).

2. variable compression ratio engine according to claim 1, it is characterized in that: the periphery of described inner sleeve (3) is that another encloses columniform key seat, four equally distributed pin-and-holes are arranged at key seat top, the plunger of lock pin (2) is that cross section is trapezoidal arc structure and matches with the lock groove of piston upper body (1) inwall, the pin tail of lock pin (2) is that shaft-like shape structure is connected by attachment hole with the head end of reed (5), has four equally distributed boss at the bottom of the seat of inner sleeve (3).

3. variable compression ratio engine according to claim 1, it is characterized in that: described piston upper body (1) point section part has four equally distributed pilot holes, the inwall place of piston upper body (1) has upper and lower two circle cross sections to be trapezoidal lock groove.

4. variable compression ratio engine according to claim 1, it is characterized in that: described piston lower body (9) point section is cast with four equally distributed guide plates and is inserted in four corresponding equally distributed pilot holes of piston upper body (1), piston lower body (9) bottom surface has four frustoconic shape shrinkage pools.

5. variable compression ratio engine according to claim 1, is characterized in that: described reed (5) is the elastic metallic structure that head and the tail have connection set.