JP2009008069A - Free-piston engine and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent or suppress formation of level difference in the inner surface of a cylinder bore. <P>SOLUTION: A pair of pistons 33A, 34A (33B, 34B) arranged in series to each other are slidably fitted in a cylinder housing 31, and a combustion chamber 35A (35B) is formed between the pair of pistons. This free-piston engine includes a position changing means which changes the relative positions of the pair of pistons 33A, 34A (33B, 34B) in an axis direction with respect to the cylinder housing 31 while constantly maintaining a distance between the pair of pistons 33A, 34A (33B, 34B). The relative positions thereof are changed in a manner that the position of a piston holding housing 41 slidably holding the pair of pistons is changed with respect to the cylinder housing 31 by a motor 71, or a power generation mode between the pair of pistons is changed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a free piston engine and a control method thereof.

Recently, a free piston engine has attracted attention from the viewpoint of efficiently extracting thermal energy of combustion gas. Patent Document 1 discloses a technique in which a permanent magnet provided on a piston of a free piston engine generates power by reciprocating in a magnetic field of a linear generator. Patent Document 1 discloses a structure in which a pair of pistons are slidably fitted in series with each other in one cylinder (cylinder bore), and a combustion chamber is formed between the pair of pistons. . That is, it is disclosed that when a combustion pressure in the combustion chamber is received, the pair of pistons are driven in directions away from each other.
JP 2005-155345 A

  By the way, the free piston engine has a feature that the compression ratio is variable because there is no crankshaft (the top dead center position and the bottom dead center position are not always constant). There is a case where the compression ratio is automatically changed in response to a positive change of the compression ratio or a change in operating state such as a load change such as a fuel injection amount, an ignition timing, and a power generation amount. Thus, when the compression ratio is changed, the relative positional relationship of the piston with respect to the cylinder is changed (the top dead center position or the bottom dead center position is changed).

  On the other hand, if the operation state with a constant compression ratio continues for a long time, the sliding range of the piston ring attached to the piston becomes constant, but this piston ring causes the cylinder bore inner surface to remain within a certain sliding range. Not a little, it will be worn out, and a level difference will be produced with the other part of the cylinder bore inner surface, and sludge will be easy to accumulate near this level difference. As described above, if a step is formed on the inner surface of the cylinder bore, when the compression ratio is changed, the piston ring may be caught when it exceeds the step or sludge accumulated in the vicinity thereof, or a seal leakage may occur. Cause. In particular, free piston engines are often used for applications that are operated continuously for a long time in a certain operating state, such as for driving a generator in a cogeneration system, a hybrid vehicle, etc. It is easy.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a free piston engine capable of preventing or suppressing the formation of a step on the inner surface of a cylinder bore and a control method thereof. is there.

In order to achieve the above object, the following solution is adopted in the free piston engine of the present invention. That is, as described in claim 1 in the claims,
In a free piston engine in which a pair of pistons are slidably fitted in series with each other in a cylinder bore formed in a cylinder housing, and a combustion chamber is formed between the pair of pistons.
Position change means for changing the relative positional relationship of the pair of pistons in the cylinder axial direction with respect to the cylinder housing while maintaining a constant distance between the pair of pistons when configuring the combustion chamber;
It is like that. According to the above solution, the position changing means changes the relative position of the pair of pistons in the cylinder axial direction with respect to the cylinder housing, so that the piston (piston ring) can be operated with respect to the inner surface of the cylinder bore even in the state of operation with the same compression ratio. The sliding range will be changed. As a result, even if the engine is operated with the same compression ratio for a long time, a situation in which a step is formed on the inner surface of the cylinder bore is prevented or suppressed by performing position change by the position changing means as needed.

Preferred embodiments based on the above solution are as described in claims 2 to 4 in the claims. That is,
A piston holding housing for holding the piston independently of the cylinder housing;
The position changing means is configured to change the distance between the cylinder housing and the piston holding housing in the cylinder axial direction.
(Corresponding to claim 2). In this case, the piston is not held only in the cylinder housing, but separately held in the piston holding housing, and the distance between the cylinder housing and the piston holding housing is changed to change the cylinder axis between the pair of pistons and the cylinder housing. The relative position of the direction can be changed.

  The position changing means includes a motor for changing the distance between the cylinder housing and the piston holding housing (corresponding to claim 3). In this case, since the position change itself does not involve a change in the distance between the pair of pistons, a small force is required. Therefore, the position change can be easily and accurately performed by the motor.

  The position changing means is operated when the compression ratio remains unchanged for a predetermined period (corresponding to claim 4). In this case, since the position is changed when the state where the compression ratio is unchanged continues for a predetermined period, a state where the step is formed in consideration of a state in which a step may be formed on the inner surface of the cylinder bore. Prevention or suppression can be performed easily and reliably.

In order to achieve the above object, the following solution is adopted in the control method of the free piston engine in the present invention. That is, as described in claim 5 in the claims,
In a control method of a free piston engine in which a pair of pistons are slidably fitted in series with each other in a cylinder bore formed in a cylinder housing, and a combustion chamber is formed between the pair of pistons.
A first step of performing operation while maintaining a constant distance between the pair of pistons when the combustion chamber is configured;
A second step of changing a relative positional relationship of the pair of pistons in the cylinder axial direction with respect to the cylinder housing during the first step;
It is supposed to be equipped with. According to the said solution technique, the control method of the free piston engine of Claim 1 is provided.

Preferred embodiments based on the above solution are as described in claims 6 and below in the scope of claims. That is,
Each of the pair of pistons generates power,
In the first step, the total power generation amount by the pair of pistons is made equal to each other.
(Corresponding to claim 6). In this case, a specific operation mode in the first step is provided in relation to power generation.

  In the second step, power generation modes by the pair of pistons are different from each other (corresponding to claim 7). In this case, a specific operation mode in the second step is provided in relation to power generation. Further, the position can be changed by changing the power generation mode, which is preferable in terms of simplification of the structure and cost reduction.

  In the second step, the timing for generating power in one cycle is different between the pair of pistons (corresponding to claim 8). In this case, a more specific power generation mode in the second step is provided.

  In the second step, the power generation load in one cycle is made different between the pair of pistons (corresponding to claim 9). In this case, a specific operation mode in the second step is provided in relation to the power generation load. Further, the position can be changed by changing the power generation load, which is preferable in terms of simplification of the structure and cost reduction.

  According to the present invention, a situation where a step is formed on the inner surface of the cylinder bore can be prevented or suppressed.

  FIG. 1 shows an embodiment in which a free piston engine is used for supplying power to a motor that drives an automobile as a vehicle. In FIG. 1, reference numeral 1 denotes a driving (traveling) motor, which is an AC motor in the embodiment. Reference numerals 2R and 2L denote left and right drive wheels (front wheels or rear wheels). The drive wheels 2R and 2L are driven by the motor 1 via the differential gear 3.

  Reference numeral 10 denotes a power generation unit, and the power generation unit 10 is configured as a unit body including a free piston engine 11 including a piston and a cylinder and a generator 12. The free piston engine 11 drives the generator 12, and the electric power (alternating current) generated by the generator 12 is converted into direct current by the rectifier 20 and then supplied to the motor 1 via the DC-AC converter 21. On the other hand, surplus power is supplied to the battery 22. In addition, power from the battery 22 is supplied to the motor 1 via the DC-AC converter 21. In order to recover regenerative energy during braking, the electric power generated by the motor 1 is converted into direct current by the rectifier 23 and then boosted by the DC-DC converter 24 and supplied to the battery 22 during braking.

The flow of power supply according to the driving state of the automobile is performed, for example, as follows, and the maximum power generation amount by the free piston engine 10 is sufficiently large to ensure the maximum output by the motor 1. .
(1) When the required power generation amount is very small At the time of starting or at an extremely light load, and when the storage amount of the battery 22 is large. At this time, power generation by the generator 12 is not performed (the free piston engine 11 is stopped), and power is supplied to the motor 1 only from the battery 22.
(2) When the required power generation amount is small It is when the battery 22 has a large amount of stored power during light load to medium load. At this time, power is generated by the generator 12 (the free piston engine 11 is operated), and electric power is supplied exclusively from the generator 12 to the motor 1 (a small amount of surplus power is generated to generate surplus power. The battery 22 may be charged).
(3) When the required power generation amount is medium to large When the power storage amount of the battery 22 is small during light load to high load. At this time, the generator 12 generates sufficient electric power more than necessary for traveling (the free piston engine 11 is operated), and the electric power is supplied from the generator 12 to the motor 1 and sufficient surplus power is generated. The battery 22 is charged.
(4) Regenerative braking When the motor 1 functions as a generator driven by the drive wheels 2R, 2L. At this time, the electric power generated by the motor 1 is stored in the battery 22. In addition, although the free piston engine 11 may be stopped, the operation can be continued at an extremely low speed in preparation for the next power generation.

  Next, an example of the power generation unit 10 will be described with reference to FIG. First, focusing on the portion of the free piston engine 11, the free piston engine 11 is substantially composed of two sets of the first engine 30A and the second engine 30B. A cylinder housing 31 is formed with two first cylinder bores 32A and second cylinder bores 32B that are parallel to each other. A pair (two) of pistons 33A and 34A are slidably fitted in the first cylinder bore 32A, and one combustion chamber 35A is formed between the pair of pistons 33A and 34A. Similarly, in the second cylinder bore 32B, a pair (two) of pistons 33B and 34B are slidably fitted, and one combustion chamber 35B is formed between the pair of pistons 33B and 34B. ing.

  A scavenging port 36A and an exhaust port 37A are opened in the combustion chamber 35A with an interval in the cylinder axis direction. Similarly, a scavenging port 36B and an exhaust port 37B are also opened in the combustion chamber 35B with an interval in the cylinder axis direction. Each engine 30A, 30B is a two-cycle self-ignition type, and when the intake air supplied from the scavenging port 36A (36B) is combusted in the combustion chamber 35A (35B), a pair of pistons 33A and 34A (33B 34B) are driven away from each other, and the exhaust gas in the combustion chamber 35A (35B) is discharged to the outside from the exhaust port 37A (37B). As will be described later, when the pistons of the two engines 30A and 30B are connected to each other and, for example, the pistons 33A and 34A of the first engine 30A are separated from each other, the pistons 33B and 34B of the second engine 30B are They are linked so as to approach each other, and the other engine is compressed by the combustion pressure of one engine. This eliminates the need for a separate return spring for urging the piston in the return direction for compression.

  Next, a description will be given focusing on the generator 12 portion. First, reference numeral 41 denotes a piston holding housing. The piston holding housing 41 is disposed with respect to the cylinder housing 31 with a gap in the cylinder axial direction. The piston holding housing 41 includes a total of four sets of linear generators 43A, 44A, 43B, and 44B that are spaced apart in a direction perpendicular to the cylinder axial direction. That is, each of the generators 43A, 44A, 43B, and 44B includes a fixed cylindrical power generation coil 45 and a magnet (permanent magnet or electromagnet) 46 slidably fitted in the power generation coil 45. The moving direction of each magnet 46 is the cylinder axis direction.

  The magnet 46 of the generator 43A is connected to the piston 33A via a connecting member 53A. The magnet 46 of the generator 44A is connected to the piston 34A via a connecting member 54A. The magnet 46 of the generator 43B is coupled to the piston 33B via a coupling member 53B. The magnet 46 of the generator 44B is connected to the piston 34B via a connecting member 54B. Furthermore, the magnet 46 (that is, the piston 33A) of the generator 43A and the magnet 46 (that is, the piston 34B) of the generator 44B are connected by the connecting member 55, and the magnet 46 (that is, the piston 34A) of the generator 44A and the generator 43B. The magnet 46 (that is, the piston 33 </ b> B) is connected by a connecting member 56. For example, when the pistons 33A and 34A of the first engine 30A are separated from each other by such connection, the pistons 33B and 34B of the second engine 30B are linked so as to approach each other (the pistons 33B and 34B are connected to each other). When separating, the pistons 33A and 34A approach each other), and the other engine is compressed by the combustion pressure of one engine. This eliminates the need for a separate return spring for urging the piston in the return direction for compression.

  In FIG. 2, reference numeral 61 denotes a base member, and the base member 61 is fixed to the installation surface 62. The installation surface 62 is, for example, a vehicle body (frame) in the case of an automobile, and an installation floor surface in the case of a cogeneration system. On the base member 61, the cylinder housing 31 and the piston holding housing 41 are installed. The cylinder housing 31 is held on the base member 61 via a slider 63 so that the cylinder housing 31 can be displaced within a predetermined range (for example, 20 mm) in the cylinder axial direction. On the other hand, the piston holding housing 41 is fixed on the base member 61. Thereby, the cylinder housing 31 can be displaced relative to the piston holding housing 41 in the cylinder axial direction.

  In order to displace the cylinder housing 31 relative to the piston holding housing 41, a pinion 72 that is rotationally driven by a motor 71 is held in the piston holding housing 41. On the other hand, a rack 73 engaged with the pinion 72 is fixed to the cylinder housing 31. The rack 73 extends in the cylinder axis direction. As a result, when the pinion 72 is rotated forward and backward by the motor 71, the cylinder housing 31 is moved closer to and away from the piston holding housing 41. By controlling the rotational position of the motor 71, the cylinder housing is controlled. The relative distance between the piston 31 and the piston holding housing 41 is changed to a desired size. Of course, the engines 30A and 30B have the same specifications and are operated under the same conditions for the intake air amount, the fuel supply amount, and the like.

  The rotational position of the motor 71 is controlled by a controller (control unit) U configured using a microcomputer. A position signal detected by the position sensor 75 is input to the controller U. The position sensor 75 is, for example, a linear sensor and detects the displacement position of a certain piston, for example, the piston 33A, and particularly detects the stroke end position (the top dead center position or the bottom dead center position). detection). For example, when the top dead center position detected by the position sensor 75, for example, the piston 33A does not change, it indicates that the operation is continued with the same compression ratio, and when the detected top dead center position is changed. Indicates that the compression ratio has been changed.

  In this embodiment, for example, when the position sensor 75 detects that the top dead center position of the piston 33A is the same position for a predetermined period (for example, 10 seconds), the motor 71 moves the cylinder housing 31 to the piston. Relative displacement with respect to the holding housing 41 (by changing the relative positional relationship of the pistons 33A to 34B with respect to the cylinder housing 31) prevents or suppresses the formation of a step on the inner surface of the cylinder bore 32A (32B). It is like that.

  Next, with reference to FIG. 3, focusing on the piston 33A, a situation is shown in which a step is formed on the inner surface of the cylinder bore. In FIG. 3, when the operation is continued for a long time with the same compression ratio, the piston 33A at the top dead center position is indicated by a solid line, and the position of the piston ring 38 at that time is indicated by a symbol P. When the piston 33A is operated with the same compression ratio and the piston 33A, that is, the piston ring 38 is reciprocated within the range of the stroke L1, continues for a long time, the stroke L1 portion of the cylinder bore 32A is compared with the other portions. As the wear progresses, a step is easily formed at the end of the stroke L1. Then, sludge is likely to accumulate in the portion indicated by the reference symbol P that is the top dead center side end of the stroke L1.

  When the operation state at the same compression ratio continues for a predetermined period, the piston moves when the cylinder housing 31 is displaced in the cylinder axial direction as described above to operate at the same compression ratio as before the cylinder housing 31 is displaced. The position of 33A is relatively changed as shown by the one-dot chain line in FIG. By performing such displacement of the cylinder housing 31 in the cylinder axis direction every time the same operation state continues for a predetermined period, a situation in which a step is formed on the inner surface of the cylinder bore or a situation in which sludge accumulates is prevented or Will be suppressed.

  FIG. 4 is a flowchart showing a control example of the present invention. This flowchart will be described below. In the following description, Q indicates a step. First, after the accelerator opening and the vehicle speed are read in Q1, the required power generation amount in the generator 12 is determined based on the accelerator opening and the vehicle speed in Q2. In Q3, a fuel injection amount for satisfying the determined required power generation amount is determined, and fuel injection is executed at a predetermined injection timing.

  After Q3, at Q4, it is determined whether or not the piston stroke end position (particularly the top dead center position) detected by the position sensor 75 has changed. When the determination in Q4 is NO, it is determined whether or not a state in which there is no change in the piston position has continued for a predetermined time (for example, 10 seconds). If YES in Q5, the motor 71 is driven in Q6 to displace the cylinder housing 31 relative to the piston holding housing 41 (control for preventing or suppressing the formation of a step on the inner surface of the cylinder bore). If YES in Q4 or if NO in Q5, the process returns without passing through Q6.

  The displacement (one displacement) of the cylinder housing 31 in Q6 can be performed as follows, for example. That is, it is displaced by a predetermined distance (for example, 1 mm) toward one stroke end, and when it is displaced to the one stroke end, it is displaced by a predetermined distance (for example, 1 mm) toward the other stroke end. In a predetermined distance range (for example, 12 mm when the maximum stroke of the piston is 80 mm), the displacement can be made to reciprocate with the same amount of displacement per stroke. In addition, the setting of the displacement amount and the displacement direction can be selected as appropriate, for example, the displacement amount and the displacement direction are set using a random number table so that the cylinder housing 31 is displaced. The cylinder housing 31 is driven by the motor 71 because the distance between the pair of pistons 33A and 34A (33B and 34B) remains constant, that is, it does not have to be performed against the combustion pressure, so the force is small. It will be.

  5 and 6 show a second embodiment of the present invention, and the same components as those in the above-described embodiment are denoted by the same reference numerals, and redundant description thereof will be omitted (this is the following third case). The same applies to the following embodiments). In the present embodiment, the power generation modes by the pair of pistons 33A, 34A (generators 43A, 44A) are made different from each other, so that the distance between the pair of pistons 33A, 34A is kept constant while the pair of pistons 33A, 34A, The relative positional relationship in the cylinder axis direction with respect to the cylinder housing 31 of 34A is changed (the same applies to the power generation mode by 33B and 34B). For this reason, in this embodiment, the cylinder housing 31 and the piston holding housing 41 are integrated, and the motor 71 is not provided.

  In order to make the power generation mode by each piston 33A, 34A, 33B, 34B different, as shown in FIG. 5, between one end of the power generation coil 45 and the input terminal of the rectifier 20 in each generator 43A, 43B, 44A, 44B. A switch 81 is connected between them. The switch 81 is controlled to be opened and closed by the controller U, and is duty controlled in this embodiment. As the switch 81, an appropriate switch such as a relay switch or a switching transistor can be used as long as it can cope with responsiveness by duty control.

  The power generation mode per cycle by the pair of pistons 33A and 34A is equal to each other when it is not necessary to change the relative positions of the pair of pistons 33A and 34A with respect to the cylinder housing 31.

  On the other hand, when changing the relative position, the power generation mode is changed between the pair of pistons 33A and 34A. That is, for example, as shown in FIG. 6, power generation by one piston 33 </ b> A is performed on an average over the entire period of one cycle, as shown in FIG. On the other hand, the power generation by the other piston 34A is concentrated and executed only in the first half of one cycle, as shown in FIG. 6 (b). However, in the embodiment, the total power generation amount per cycle by the pistons 33A and 34A is set to be equal to each other, but the total power generation amount may be different. Thereby, the speed of the piston 34A is rapidly decreased from the initial stage of combustion, while the speed of the piston 33A is slowly decreased. In a state where the pair of pistons 33A and 34A are closest to each other so as to form the combustion chamber 35A, the pistons 33A and 34A are relatively displaced with respect to the cylinder housing 31 toward the one piston 34A. The In addition, since the direction of the power generation of the pistons 33A and 34B (34A and 33B) mechanically connected to each other is controlled to be the same, the deceleration rate of the pistons mechanically connected to each other is equal, This is preferable in reducing the reaction force from the piston applied to the connecting members 53A, 53B, 54A, 54B and 55,56.

  As described above, in this embodiment, the cylinders of the pair of pistons 33A and 34A (33B and 34B) with respect to the cylinder housing 31 are changed by a simple method of changing the power generation mode by the pair of pistons 33A and 34A (34B and 34B). The relative position in the axial direction can be changed. In addition, the amount of power generation can be changed substantially steplessly by duty control. Needless to say, the cylinder housing 31 and the piston holding housing 41 can be integrally formed, and the motor 71 is unnecessary, which is preferable in terms of simplification of the structure and cost reduction as a whole.

  FIG. 7 shows a third embodiment of the present invention. FIG. 7 corresponds to the second embodiment, and the power generation amount can be changed in stages. That is, the power generation coils (corresponding to 45) of the generators 43A, 44A, 43B, 44B are divided into a plurality (three in the embodiment) of coils 45a to 45c, and a plurality of magnets (corresponding to 46). The divided magnets 46a to 46c are divided. A switch 82a, 82b or 82c (corresponding to the switch 81) controlled by the controller U is interposed between one end of each of the divided coils 45a to 45c and the rectifier 20.

  The mode in which the switches 82a to 82c are turned on is different between the pair of pistons 33A and 34A (33B and 34B), so that the total power generation amount per cycle is equal to each other, and the pair of pistons 33A and 34A The relative position of the cylinder housing 31 in the axial direction can be changed. For example, the switches 82a to 82c corresponding to one piston 34A are all turned on only in the first half of one cycle, while the switches 82a to 82c corresponding to the other piston 33A are, for example, two switches for the entire period of one cycle. By turning on only two switches of the switches 82a and 82b, the relative positions of the pair of pistons 33A and 34A with respect to the cylinder housing 31 are changed.

  FIG. 8 shows a fourth embodiment of the present invention. In the present embodiment, only one power generation coil 45 of the pair of pistons 33A and 34A (the same applies to 33B and 34B) is provided as in the case of FIG. 5, while a rectifier (corresponding to 20) is provided for the piston 33A. The rectifier 20a for the piston and the rectifier 20b for the piston 34A are separately provided. In addition, in order to connect one end of each power generating coil 45 to the rectifier 20a or 20b, it is directly connected to the rectifier 20a or 20b, and in parallel with this, the switch 83a or 83b controlled by the controller U (switch 81a or 83b). Corresponding) and a capacitor 84 as an electrical load are also connected. In the present embodiment, the switch 83a is for one piston 33A, and the switch 83b is for the other piston 34A.

  By turning on one of the switches 83a and 83b and turning off the other, the power generation load of the piston corresponding to the switch on the ON side is increased with respect to the power generation load of the other piston. Will be. Of course, when both switches 83a and 83b are both ON (or both OFF), the power generation loads in the pair of pistons 33A and 34A are equalized. When the relative position of the pair of pistons 33A and 34A with respect to the cylinder housing 31 is changed, it can be performed by the ON / OFF control of the switches 83a and 83b described above. That is, by changing the timing of turning on the switches 83a and 83b per cycle, the total power generation amount per cycle is set to be equal between the pair of pistons 33A and 34A, and the cylinders of the pair of pistons 33A and 34A are set. The relative position with respect to the housing 31 can be changed to a position closer to the piston where the power generation load is initially increased.

  Although the embodiment has been described above, the present invention is not limited to the embodiment, and can be appropriately changed within the scope described in the scope of claims. For example, the invention includes the following cases. . The free piston engine 11 may be only one engine 30A (or only 30B) (single cylinder), or three sets or more (three cylinders or more). When the piston is not adopted as a pair structure as shown in FIG. 2, for example, a force for displacing the piston in the compression direction may be obtained by a separately provided return spring.

The generator 12 (43A to 44B) is not limited to a linear type, but may be a rotary type (for example, a reciprocating motion of a piston is converted into a normal / reverse rotational motion by a rack and pinion mechanism to To generate electricity by rotating forward and backward). The free piston engine may be a spark ignition type or may adopt an appropriate type such as a four-cycle type. While fixing the cylinder housing 31 (for example, fixing the cylinder housing 31 to the base member 61), the pair of pistons 33A and 34A (33B and 34B) are displaced with respect to the cylinder housing 31 so that the relative distance is not changed. You may make it make it. For example, in the structure of FIG. 2, the cylinder housing 31 and the piston holding housing 41 may be fixed to the base member 61, and for example, the connecting members 55 and 56 may be displaced by the same distance in the cylinder axial direction. . The relative distance between the cylinder housing 31 and the piston holding housing 41 may be changed not only by the motor 71 but also by a hydraulic actuator.
The change of the relative distance between the cylinder housing 31 and the piston holding housing 41 is not limited to the control using the position sensor 75. For example, the engine operating state (for example, the same fuel injection amount or the same request) Appropriate conditions can be set, for example, by changing the relative distance when the power generation amount is maintained for a predetermined period. Of course, the object of the present invention is not limited to what is explicitly stated, but also implicitly includes providing what is substantially preferred or expressed as an advantage.

The whole system diagram which shows embodiment at the time of utilizing a free piston engine for the electric power feeding to the motor for driving | running | working a motor vehicle. 1 is a side sectional view showing an example of a free piston engine according to the present invention. The principal part side surface sectional drawing explaining the condition where a level | step difference is formed in a cylinder bore inner surface. The flowchart which shows the example of control of this invention. The circuit diagram of the coil part for electric power generation which shows the 2nd Embodiment of this invention. 6 is a time chart showing a control example of the switch shown in FIG. 5. FIG. 6 is a circuit diagram illustrating a third embodiment of the present invention and corresponding to FIG. 5. FIG. 6 is a circuit diagram illustrating a fourth embodiment of the present invention and corresponding to FIG. 5.

Explanation of symbols

10: Power generation unit 11: Free piston engine 12: Generator 20: Rectifier 20a, 20b: Rectifier (FIG. 8)
30A: first engine 30B: second engine 31: cylinder housing 32A: first cylinder bore 32B: second cylinder bore 33A, 34A: piston 33B, 34B: piston 35A, 35B: combustion chamber 38: piston ring 41: piston holding housing 45: Coil for power generation 46: Permanent magnets 45a to 45c: Split coil (FIG. 7)
61: Base member 63: Slider 71: Motor 72: Pinion 73: Rack 75: Position sensor 81: Switches 82a to 82c: Switches (FIG. 7)
83a, 83b: switches (FIG. 8)
84: Capacitor (Fig. 8)
U: Controller

Claims (9)

In a free piston engine in which a pair of pistons are slidably fitted in series with each other in a cylinder bore formed in a cylinder housing, and a combustion chamber is formed between the pair of pistons.
Position change means for changing the relative positional relationship of the pair of pistons in the cylinder axial direction with respect to the cylinder housing while maintaining a constant distance between the pair of pistons when configuring the combustion chamber;
This is a free piston engine. In claim 1,
A piston holding housing for holding the piston independently of the cylinder housing;
The position changing means is configured to change the distance between the cylinder housing and the piston holding housing in the cylinder axial direction.
This is a free piston engine. In claim 1,
The free piston engine, wherein the position changing means includes a motor for changing a distance between the cylinder housing and the piston holding housing. In any one of Claims 1 thru | or 3,
The free piston engine, wherein the position changing means is operated when the compression ratio remains unchanged for a predetermined period. In a control method of a free piston engine in which a pair of pistons are slidably fitted in series with each other in a cylinder bore formed in a cylinder housing, and a combustion chamber is formed between the pair of pistons.
A first step of performing operation while maintaining a constant distance between the pair of pistons when the combustion chamber is configured;
A second step of changing a relative positional relationship of the pair of pistons in the cylinder axial direction with respect to the cylinder housing during the first step;
A method of controlling a free piston engine, comprising: In claim 5,
Each of the pair of pistons generates power,
In the first step, the total power generation amount by the pair of pistons is made equal to each other.
A control method for a free piston engine. In claim 6,
In the second step, the power generation mode by the pair of pistons is different from each other, and the control method of the free piston engine. In claim 6,
The method of controlling a free piston engine, characterized in that, in the second step, the timing for generating power in one cycle is different between the pair of pistons. In claim 6,
In the second step, the power generation load in one cycle is made different between the pair of pistons, and the control method for a free piston engine.

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