JP2008232105A - Free piston engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a free piston engine in which pistons rotate. <P>SOLUTION: Two pistons of a first piston 41A (41B) and second piston 42A (42B) at the cylinder center as a center are arranged in a round cylinder K1 (K2) formed in a casing 30 in a normal and reverse-rotational state, and a combustion chamber 61A (61B) sandwiched by tow pistons 41A and 42A (41B and 42B) is formed in the periphery direction of the cylinder. A first output shaft 51 integrated together with the first piston 41A is retained in the casing 30 at the center of the cylinder as its center in a normal and reverse-rotational state, and a second output shaft 52 integrated together with the second piston 42A is also retained in the casing 30 in a normal and reverse-rotational state. Rotary generators 81 and 91 are driven by the first output shaft 51 and second output shaft 52. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a free piston engine.

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 that reciprocates linearly moves to generate power by reciprocating in a magnetic field of a linear generator. In Patent Document 2, one combustion chamber is formed between two pistons fitted in a cylinder and reciprocally moved linearly, and the two pistons are driven in the separation direction by the combustion pressure in the combustion chamber. A free piston engine has been proposed.
JP 2003-343202 A JP 2005-155345 A

  As described in the above-mentioned patent documents, when generating power in a free piston engine, a linear generator is used as the generator in response to the reciprocating linear movement of the piston. The power generation efficiency is lower than that of the generator of the type, and some measures are desired in this respect. More specifically, when the length of the power generating coil and the permanent magnet (the length of the permanent magnet in the reciprocating direction) is set to be the same, the power generating coil corresponding to the permanent magnet is near the end of the reciprocating stroke of the permanent magnet. A state that does not exist is formed, and thus the power generation efficiency is poor. In addition, when the power generation coil is disposed long over the entire length of the reciprocating linear motion trajectory of the permanent magnet, the power generation coil has a portion that does not participate in power generation for a considerable length, and the total length of the generator is extremely long. There is also the problem of becoming larger. After all, such a problem is caused by the reciprocating linear motion of the piston in the conventional free piston engine.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a free piston engine in which a piston rotates.

In order to achieve the above object, the following solution is adopted in the present invention. That is, as described in claim 1 in the claims,
Two pistons, a first piston and a second piston, are arranged in a circular cylinder formed in the casing so as to be able to rotate forward and backward around the center of the cylinder, and are sandwiched between the two pistons in the circumferential direction of the cylinder. Combustion chamber is configured,
A first output shaft that is rotated forward and backward integrally with the first piston about the center of the cylinder is rotatably held in the casing, and is rotated forward and backward integrally with the second piston about the center of the cylinder. The second output shaft is rotatably held,
A rotary generator that generates power by forward and reverse rotation of at least one of the first output shaft and the second output shaft;
It is like that.

  According to the above solution, each piston, that is, each output shaft, is driven to rotate forward and backward as a rotational motion around the cylinder center in accordance with combustion. Therefore, when the generator is driven by the output shaft, it is possible to use a rotary generator with good power generation efficiency. In addition, since the driving force due to combustion is directly taken out as the forward / reverse rotational motion of each output shaft, for example, a rotary generator can be installed without using a special mechanism for changing the reciprocating motion into the forward / reverse rotational motion. It can be used.

A preferred mode based on the above solution is as described in claim 2 and the following claims. That is,
In the cylinder, a scavenging pump chamber is formed that is separated from the combustion chamber by the two pistons and is sandwiched by the two pistons in the circumferential direction of the cylinder. 2 correspondence). In this case, a scavenging pump chamber can be formed in one cylinder in addition to the combustion chamber by effectively using the two pistons. In other words, the free piston engine itself also functions as a scavenging pump, and it becomes unnecessary to provide a separate scavenging pump.

  The generator is a rotary first generator that generates power by forward and reverse rotation of the first output shaft, and a rotary second generator that generates power by forward and reverse rotation of the second output shaft. (Claim 3). In this case, a rotary generator is individually provided for each output shaft, which is preferable in terms of increasing the degree of freedom in arranging the generators and reducing the size of each generator.

Two cylinders each having the two pistons, one combustion chamber, and one pump chamber are arranged in series as a first cylinder and a second cylinder,
The first output shaft and the second output shaft are disposed across the first cylinder and the second cylinder, respectively;
One piston in the first cylinder and one piston in the second cylinder are integrated via the first output shaft, and the other piston in the first cylinder and the other piston in the second cylinder Are integrated via the second output shaft,
The combustion stroke in the first cylinder and the combustion stroke in the second cylinder are set to be different so that the combustion chamber in the second cylinder is compressed by the combustion pressure in the combustion chamber in the first cylinder. And the integration relationship of each piston with respect to each output shaft is set,
(Corresponding to claim 4). In this case, the first output shaft and the second output shaft can be used for two cylinders. Moreover, it becomes a multi-cylinder free piston engine, which is preferable for reducing vibration. Furthermore, there are various effects such that it is not necessary to separately provide a return spring for returning each piston in the compression direction.

The generator is a rotary first generator that generates power by forward and reverse rotation of the first output shaft, and a rotary second generator that generates power by forward and reverse rotation of the second output shaft;
The first output shaft is hollow;
The second output shaft is fitted in the first output shaft so as to be relatively rotatable;
The first generator is disposed at an intermediate position between the first cylinder and the second cylinder;
The second generator is disposed on the opposite side of the first generator across one cylinder in the cylinder arrangement direction;
(Corresponding to claim 5). In this case, a total of four large functional parts of two cylinders and two generators can be arranged in series with each other.

Two combustion chambers separated from each other by the two pistons are formed in the cylinder,
The combustion strokes of the two combustion chambers are different from each other so that the other combustion chamber is compressed by the combustion pressure in one of the two combustion chambers.
(Corresponding to claim 6). In this case, it is preferable to form two combustion chambers in one cylinder and increase the output per forward / reverse rotation of one piston. Further, the two pistons can be returned in the compression direction without using a separate return spring.

  According to the present invention, it is possible to provide a free piston engine in which a piston is rotationally moved.

  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 (running) motor, which is an AC motor in the embodiment. Reference numerals 2R and 2L denote left and right driving wheels (front wheels or rear wheels). The driving wheels 2R and 2L are driven by the motor 1 via the differential gear 3.

  Reference numeral 10 denotes a free piston engine. The free piston engine 10 is configured as a unit body including an engine body 11 including a piston and a cylinder and a generator 81.91 described later. The engine body 11 drives the generators 81 and 91, and the electric power (alternating current) generated by the generators 81 and 91 is converted into direct current by the rectifier 20, and then the motor via the DC-AC converter 21. 1, 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, the generators 81 and 91 do not generate power (the free piston engine 10, that is, the engine main body 11 is stopped), and power is supplied only from the battery 22 to the motor 1.
(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 generators 81 and 91 (the free piston engine 10 is operated), and electric power is supplied exclusively from the generators 81 and 91 to the motor 1 (a little surplus power is generated to generate power). The surplus power may be stored in the battery 22).
(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 generators 81 and 91 generate sufficient electric power more than necessary for traveling (the free piston engine 10 is operated), and the electric power is supplied from the generators 81 and 91 to the motor 1. Excess electric power is stored in the battery 22.
(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 10 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 free piston engine 10 will be described with reference to FIG. In FIG. 2, the engine body 11 has a casing 30, and a first cylinder K <b> 1 and a second cylinder K <b> 2 are configured in the casing 30. The cylinders K1 and K2 are arranged in series with an interval in the direction of a predetermined axis L that is the center of the cylinder. Between the cylinders K1 and K2, the first generator 81 described above which is a rotary type is disposed. Further, in the predetermined axis L direction, a rotary second generator 91 is disposed on the opposite side of the second cylinder K2 from the first generator 81.

  An example of each cylinder K1, K2 is shown in FIGS. Since the cylinders K1 and K2 are substantially the same except that the combustion strokes are set to be different from each other, paying attention to the first cylinder K1 and referring to FIG. I will explain.

  In FIG. 3, the first cylinder K1 constitutes a circular space centered on a predetermined axis L, and in this first cylinder K1, there are two pistons, a first piston 41A and a second piston 42A. It is arranged. The casing 30 holds the first output shaft 51 and the second output shaft 52 so as to be rotatable about a predetermined axis L, respectively. The first output shaft 51 is hollow, and the second output shaft 52 is fitted in the first output shaft 51 so as to be relatively rotatable.

  Of the output shafts 51 and 52 that have a relation between the inner and outer dual structures, the center end of the first piston 41A in the radial direction (the radial direction of the first cylinder K1) is integrated with the outer output shaft 51. It has become. Further, a part of the inner second output shaft 52 is exposed in the first cylinder K1, and the radial center side end portion of the second piston 42A is integrated with the second output shaft 52. It has become. Each of the pistons 41A and 42A has an arc shape so as to divide the inside of the cylinder K1 in the cylinder circumferential direction, and the first piston 41 can rotate forward and backward around the first output shaft 51. The two pistons 42 </ b> A can rotate forward and backward about the second output shaft 52.

  In the first cylinder K1, one combustion chamber 61A is formed by the two pistons 41A and 42A described above and sandwiched between the pistons 41A and 42A in the cylinder circumferential direction. Further, one pump chamber 62A sandwiched between the two pistons 41A and 42A in the standing circumferential direction is formed on the side opposite to the combustion chamber 61A in the radial direction of the first cylinder K1. When the two pistons 41A and 42A are displaced in directions away from each other, that is, when they are displaced in a direction in which the combustion chamber 61A is expanded, the pump chamber 62A is compressed.

  In the casing 30, an intake port 63A and an exhaust port 64A are formed so as to open into the first cylinder 30, and a scavenging port 65A is formed. One end of the scavenging port 65A is always opened to the pump chamber 62A, and the other end is opened in the first cylinder K1 at a predetermined position opened in the combustion chamber 61A in the vicinity immediately after the combustion chamber 61A enters the exhaust stroke. Is open. In the embodiment, the first cylinder K1 is a two-cycle self-ignition type.

  The second cylinder K2 is shown in FIG. 4 (corresponding to FIG. 3). The second cylinder K2 is configured in substantially the same manner as the first cylinder K1, and the same constituent elements as those in the first cylinder K1 are replaced with the reference sign “A” used in the first cylinder K1. By using the symbol “B”, detailed description thereof is omitted.

  The aforementioned output shafts 51 and 52 are used in common for the two cylinders K1 and K2. In other words, the output shafts 51 and 52 are disposed across the two cylinders K1 and K2, and the inner second output shaft 52 is used as a drive for the second generator 91. It is longer than one output shaft 51.

  The first piston 41A in the first cylinder K1 and the first piston 41B in the second cylinder K2 are connected (interlocked) via the first output shaft 51. Further, the second piston 42A in the first cylinder K1 and the second piston 42B in the second cylinder K2 are connected (interlocked) via the second output shaft 52. Details of the connection mode of the pistons 41A, 42A, 41B, and 42B via the output shafts 51 or 52 are shown in FIGS. That is, FIG. 8 shows a connection mode through the first output shaft 51, FIG. 9 shows a connection mode through the second output shaft 52, and FIG. 9 shows an assembled state in which 9 is combined.

  Of the two cylinders K1 and K2, it is set so that the combustion pressure in the combustion chamber in one cylinder is compressed in the combustion chamber in the other cylinder. In other words, the combustion strokes are set to be different from each other between the two cylinders K1 and K2. For example, when one cylinder is in the expansion stroke, the other cylinder is set in the compression stroke. In order to satisfy such a relationship, the connection relationship between the cylinder pistons 41A, 42A and 41B, 42B using the output shafts 51, 52 is also selected and performed. More specifically, for example, when the first piston 41A and the second piston 42A in the first cylinder K1 are separated from each other in the cylinder circumferential direction (when the combustion chamber 61A is expanded, corresponding to FIG. 3), The connection relationship is set so that the first piston 41B and the second piston 42B in the two cylinders K2 approach each other in the cylinder circumferential direction (when the combustion chamber 61B is compressed, corresponding to FIG. 4).

  As shown in FIG. 5, the casing 30 is formed by integrating a plurality of divided casings 30 </ b> A to 30 </ b> F divided in a predetermined axis L direction in the drawing. That is, the divided casing 30A is located at the left end of FIG. 1, closes the end surface of the first cylinder K1, and forms a scavenging port 65A. The divided casing 30B is for the first cylinder K1 configuration. The divided casing 30 </ b> C is for the first generator 81. The divided casing 30D closes the end surface of the second cylinder K2, and forms a scavenging port 65B (not shown in FIG. 5). The divided casing E is for the second cylinder K2. The divided casing 30F is for the second generator 91. FIG. 6 shows a state in which the divided casings 30A, 30C, 30D, and 30F are excluded from the state of FIG.

  FIG. 10 shows the details of the first generator 81 portion which is a rotary type. In FIG. 10, reference numeral 71 denotes a rotor that is integrated with the first output shaft 51 and rotates in the forward and reverse directions. The rotor 71 spans the entire circumferential length of the first output shaft 51 (the entire circumference of 360 degrees). The permanent magnet 72 (see FIG. 1) is held. Reference numeral 73 denotes a stator fixed to the casing 30, and a power generation coil 74 (see FIG. 1) is held by the stator 73 over the entire circumferential length of the first output shaft 51 (360 degrees of the entire circumference). Has been. As described above, since the power generating coil 74 is always positioned at the portion where the permanent magnet 72 is positioned, the power generation is efficiently performed using all the permanent magnets 72 by forward and reverse rotation of the first output shaft 51. It will be.

  FIG. 11 shows details of the rotary second generator 91 portion. Since the second generator 91 is also configured substantially in the same manner as the first generator 81 shown in FIG. 10 except that it is driven by the second output shaft 52, the same reference numerals are given to the same components. Therefore, the duplicate description is omitted.

  Next, the manner in which the combustion stroke in the embodiment changes will be described in detail with particular attention to the first cylinder K1 with reference to FIGS. First, FIG. 12 shows a state in which the first cylinder K1 is in the initial stage of the compression stroke and the second cylinder K2 is in the initial stage of the expansion stroke. The state of FIG. 12 proceeds to the state of FIG. 13, and the compression of the first cylinder K1 proceeds, and accordingly, the intake port 63A starts to open to the pump chamber 65A. However, the combustion chamber 61A is not in communication with the scavenging port 65A.

  When the state shown in FIG. 13 is changed to the state shown in FIG. 14, the combustion chamber 61A reaches the end of the compression stroke, and combustion is performed immediately after this. In the state of FIG. 14, the intake port 63A is completely open to the pump chamber 65A, and a large amount of intake air (air mixture) is supplied to the pump chamber 65A.

  When combustion (ignition) is performed in the combustion chamber 61A immediately after the state of FIG. 14, each piston 41A and 42A starts to rotate in the direction opposite to that of FIGS. Initial expansion).

  When the state of FIG. 15 changes to the state of FIG. 16, the exhaust port 64A starts to open to the combustion chamber 61A and the scavenging port 65A starts to open to the combustion chamber 61A (exhaust and scavenging). Initial state).

  When the state of FIG. 16 is changed to the state of FIG. 17, the exhaust port 64A is greatly opened and the scavenging port 65A is also greatly opened with respect to the combustion chamber 61A.

  After the state of FIG. 17 which is the end of the exhaust stroke (scavenging stroke), the rotation direction of the first cylinder K1 is changed again to the state of FIG. 12, that is, the direction in which the combustion chamber 61A is compressed.

  When the first cylinder K1 shifts from the state shown in FIG. 17 to the state shown in FIG. 12 and the rotation direction of the pistons 41A and 42A is changed, this rotation direction changing force and the subsequent combustion chamber 61A are compressed. This force is ensured by the combustion pressure in the second cylinder K2.

  FIG. 18 shows a second embodiment of the present invention, in which the same reference numerals are given to the same components as those in the above-described embodiment (the reference numerals for the first cylinder K1 in the above-described embodiment are used). . In the present embodiment, only one cylinder K1 is provided. Two combustion chambers 61A and 67A are formed in one cylinder K1. More specifically, the portion configured as the pump chamber 65A in the embodiment is configured as the combustion chamber 67A. For this reason, an intake port 63A and an exhaust port 64A are individually provided in both of the combustion chambers 61A and 67A. The scavenging is performed by supplying the intake air compressed by the scavenging pump from the intake port 63A.

  Also in the embodiment of FIG. 18, two generators (corresponding to 81 and 91, not shown in FIG. 18) are individually driven by the output shafts 51 and 52. That is, the first generator 81 is arranged on one end side in the cylinder center direction (for example, the front side in the drawing in FIG. 18) across one cylinder K1, and on the other end side in the cylinder center direction (for example, on the back side in the drawing in FIG. 18). A second generator 91 is provided.

  In the embodiment shown in FIG. 18, a return spring for returning each piston 41A, 42A for compression of the combustion chamber by using the combustion pressure in one combustion chamber as a force in the direction of compressing the other combustion chamber. Is unnecessary. Further, when focusing on one cylinder, the number of times of combustion can be ensured twice as much as in the above-described embodiment by one forward and reverse rotation of the pistons 41A and 42A, which is advantageous in terms of securing a large output.

  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 number of cylinders can be appropriately selected according to the required power generation capacity, such as arranging a plurality of the structures shown in FIG. 2 or arranging a plurality of the structures shown in FIG. 10 in series, for example. Each permanent magnet 72.74 is not provided integrally with the output shaft 51 or 52, for example, a magnet holding that is linked to each output shaft 51, 52 so as to rotate forward and backward via a gear or the like. A body may be provided so that the permanent magnets 72 and 74 are held by the magnet holder.

  In the embodiment of FIGS. 2 to 4, only one cylinder may be provided. In this case, a force for compressing the combustion chamber may be ensured by using the return spring, and the return spring is disposed at a position corresponding to the pump chamber, for example, or the return spring is provided outside the casing 30. The force of the return spring may be transmitted to the piston via the output shafts 51 and 52.

  You may make it provide one generator common to each output shaft, without providing a generator separately for each output shaft 51,52. In this case, for example, one common output shaft is provided so as to be able to rotate forward and reverse, and the output shafts 51 and 52 may be linked to the common output shaft via gears (for example, rotating By interposing a gear for direction change, the rotation direction of the output from the output shafts 51 and 52 is made to coincide with the common output shaft). Further, the rotary generator may be driven only by one of the first output shaft 51 and the second output shaft 52. The specification range of the free piston engine is not limited, such as being used not only for automobiles but also for stationary power generation. The free piston engine may be a spark ignition type or may adopt an appropriate type such as a four-cycle type. 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. BRIEF DESCRIPTION OF THE DRAWINGS The 1st Embodiment of this invention is shown, The simplified side surface sectional view which shows an example of a free piston engine. FIG. 3 is a simplified cross-sectional view showing a first cylinder shown in FIG. 2. FIG. 3 is a simplified cross-sectional view showing a second cylinder shown in FIG. 2. The perspective view which shows the external appearance of the free piston engine shown in FIG. The perspective view which excludes and shows a part of division | segmentation casing from the state of FIG. The perspective view which shows the connection relation of the piston in two cylinders. The perspective view which shows the connection relation of the piston in two cylinders via the 1st output shaft among FIG. The perspective view which shows the connection relation of the piston in two cylinders via a 2nd output shaft among FIG. The principal part perspective view which shows the part of a 1st generator. The principal part perspective view which shows a 2nd generator part. In the embodiment shown in FIG. 2, the principal part perspective view which shows a mode that a piston position changes with progress of a combustion stroke. In the embodiment shown in FIG. 2, the principal part perspective view which shows a mode that a piston position changes with progress of a combustion stroke. In the embodiment shown in FIG. 2, the principal part perspective view which shows a mode that a piston position changes with progress of a combustion stroke. In the embodiment shown in FIG. 2, the principal part perspective view which shows a mode that a piston position changes with progress of a combustion stroke. In the embodiment shown in FIG. 2, the principal part perspective view which shows a mode that a piston position changes with progress of a combustion stroke. In the embodiment shown in FIG. 2, the principal part perspective view which shows a mode that a piston position changes with progress of a combustion stroke. Sectional drawing which shows the 2nd Embodiment of this invention and respond | corresponds to FIG. 3, FIG.

Explanation of symbols

10: free piston engine 11: engine main body 30: casing 41A, 41B: first piston 42A, 42B: second piston 51: first output shaft 52: second output shaft 61A, 61B: combustion chamber 62A, 62B: pump chamber 63A, 63B: Intake port 64A, 64B: Exhaust port 65A, 65B: Scavenging port 67A: Combustion chamber (FIG. 18)
71: Rotor 72: Permanent magnet 73: Stator 74: Power generation coil 81: First generator 91: Second generator

Claims (6)

Two pistons, a first piston and a second piston, are arranged in a circular cylinder formed in the casing so as to be able to rotate forward and backward around the center of the cylinder, and are sandwiched between the two pistons in the circumferential direction of the cylinder. Combustion chamber is configured,
A first output shaft that is rotated forward and backward integrally with the first piston about the center of the cylinder is rotatably held in the casing, and is rotated forward and backward integrally with the second piston about the center of the cylinder. The second output shaft is rotatably held,
A rotary generator that generates power by forward and reverse rotation of at least one of the first output shaft and the second output shaft;
This is a free piston engine. In claim 1,
A free piston characterized in that a scavenging pump chamber sandwiched by the two pistons in the circumferential direction of the cylinder is formed in the cylinder, with the two pistons being separated from the combustion chamber. engine. In claim 1 or claim 2,
The generator is a rotary first generator that generates power by forward and reverse rotation of the first output shaft, and a rotary second generator that generates power by forward and reverse rotation of the second output shaft. A free piston engine. In claim 1,
Two cylinders each having the two pistons, one combustion chamber, and one pump chamber are arranged in series as a first cylinder and a second cylinder,
The first output shaft and the second output shaft are disposed across the first cylinder and the second cylinder, respectively;
One piston in the first cylinder and one piston in the second cylinder are integrated via the first output shaft, and the other piston in the first cylinder and the other piston in the second cylinder Are integrated via the second output shaft,
The combustion stroke in the first cylinder and the combustion stroke in the second cylinder are set to be different so that the combustion chamber in the second cylinder is compressed by the combustion pressure in the combustion chamber in the first cylinder. And the integration relationship of each piston with respect to each output shaft is set,
This is a free piston engine. In claim 4,
The generator is a rotary first generator that generates power by forward and reverse rotation of the first output shaft, and a rotary second generator that generates power by forward and reverse rotation of the second output shaft;
The first output shaft is hollow;
The second output shaft is fitted in the first output shaft so as to be relatively rotatable;
The first generator is disposed at an intermediate position between the first cylinder and the second cylinder;
The second generator is disposed on the opposite side of the first generator across one cylinder in the cylinder arrangement direction;
This is a free piston engine. In claim 1,
Two combustion chambers separated from each other by the two pistons are formed in the cylinder,
A free piston engine characterized in that the combustion strokes of the two combustion chambers are different from each other so that the other combustion chamber is compressed by the combustion pressure in one of the two combustion chambers. .

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