JP2016109123A - Control device for free piston generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a free piston generator capable of controlling behavior of a piston with higher accuracy.SOLUTION: A control device 18 controls a power generation amount so that a speed of a piston 14 reaches a first speed command value (expansion stroke) and a second speed command value (compression stroke) by electric braking during power generation of a free piston generator 10. A power transmission amount is controlled by exciting a coil 26 so that the speed of the piston 14 reaches the first and the second speed command values during motoring. The control device 18 sets the first and the second speed command values in a next reciprocating period based on a top dead center position and a bottom dead center position of the piston 14 in a prescribed reciprocating period in setting the first and the second speed command values.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a control device for a free piston generator, in which a piston incorporating a magnet generates power by reciprocating in a cylinder provided with a coil.

  2. Description of the Related Art Conventionally, a free piston generator that generates electricity by reciprocating a piston in a cylinder is known. The piston can reciprocate in the cylinder without being mechanically constrained.

  Inside the cylinder, a combustion chamber is provided at one end along the reciprocating direction of the piston (longitudinal direction of the cylinder), and an air spring chamber is provided at the other end. When the fuel / air mixture is burned in the combustion chamber, the piston is pushed out of the combustion chamber toward the air spring chamber by the combustion pressure. As the piston moves, the volume of the air spring chamber is compressed. Then, a repulsive force against this compression is generated, and the piston is returned to the combustion chamber again.

  A permanent magnet is provided on the outer peripheral surface of the piston, and a coil is provided on the inner peripheral surface of the cylinder. As the piston reciprocates, the permanent magnet and the coil move relative to each other. Electric power is generated by the induced electromotive force generated at this time.

  Non-Patent Document 1 describes a method of controlling the behavior of a piston in a free piston generator. According to this, there is a mathematical formula for calculating, as energy generated by power generation, energy that is applied to the piston by combustion, energy that is stored in the air by compression of the air spring, and energy obtained by subtracting the friction energy of the piston from the sum of the friction energy of the cylinder and the piston. Have been described.

Florian Kock et al., “The Free Piston Linear Generator-Development of an Innovative, Compact, Highly Efficient Range -Extender Module), SAE International, SAE Transaction, April 8, 2013, 2013-01-1727

  By the way, in the control method based on the energy balance, there are many disturbance elements, and it is not easy to specify parameters accurately. For example, combustion variations occur in the combustion chamber, and it is difficult to accurately specify the energy applied to the piston by combustion among the above parameters. Since it becomes difficult to specify parameters, the accuracy of piston control is lowered. Accordingly, an object of the present invention is to provide a control device for a free piston generator that can control the behavior of a piston more accurately than in the past.

  The present invention relates to a control device for a free piston generator, in which power is generated by reciprocating a piston in which a magnet is incorporated in a cylinder provided with a coil. A combustion chamber is provided in the cylinder. The control device sets a first speed command value in an expansion stroke in which the piston is moved to the opposite side of the combustion chamber, and a second speed command value in a compression stroke in which the piston is moved to the combustion chamber side. Then, during power generation, the amount of power generation is controlled so that the speed of the piston reaches the first and second speed command values by electric braking, or the speed of the piston is controlled by exciting the coil during motoring. And the amount of power transmission so as to reach the second speed command value, and in setting the first and second speed command values, the top dead center position where the piston is closest to the combustion chamber in a predetermined reciprocating cycle; Based on the bottom dead center position where the piston is farthest from the combustion chamber, first and second speed command values in the next reciprocating cycle are set.

  In the above invention, it is preferable that the piston reciprocates between a combustion chamber and an air spring chamber provided in the cylinder.

  Further, in the above invention, the control device includes a difference between the actual top dead center position and the top dead center target position and a difference between the actual bottom dead center position and the bottom dead center target position in a predetermined reciprocating cycle. It is preferable to obtain the amplitude of the speed command wave having the first speed command value and the second speed command value as the peak value and the offset amount from the speed 0 of the speed command wave in the next reciprocating cycle. is there.

  In the above invention, it is preferable that the control device reduces the absolute value difference between the first and second speed command values by changing the bottom dead center target position.

  Further, in the above invention, when the generated power integrated amount being controlled with the first speed command value is larger than the generated power integrated amount being controlled with the second speed command value, the control device sets the bottom dead center target of the piston. When the position is changed so as to be separated from the stroke center position of the piston, and the generated power integrated amount controlled by the second speed command value is larger than the generated power integrated amount controlled by the first speed command value, It is preferable to change the bottom dead center target position of the piston closer to the stroke center position of the piston.

  In the above invention, it is preferable that the control device increases the air pressure of the air spring chamber as the combustion pressure in the combustion chamber increases.

  In the above invention, the control device controls the excitation current to the coil so that the piston is biased to the opposite side of the piston stop position when viewed from the stroke center position at the start of motoring. Is preferred.

  Further, in the above invention, it is preferable that the control device controls the dispatch power timing so as to pause the dispatch power while the piston is passing through the top dead center position and the bottom dead center position.

  In the above invention, it is preferable that the control device sets an area from a half value of a top dead center target position to a half value of a bottom dead center target position as an excitation area of the coil during the motoring.

  Another aspect of the present invention is a free-piston power generation in which power generation is performed by reciprocating a piston incorporating a magnet between a combustion chamber and an air spring chamber in a cylinder provided with a coil. The present invention relates to a machine control device. The control device sets a first speed command value in an expansion stroke in which the piston is moved toward the air spring chamber and a second speed command value in a compression stroke in which the piston is moved toward the combustion chamber. At the time of power generation, the amount of power generation is controlled so that the speed of the piston reaches the first and second speed command values by electric braking, or the speed of the piston is controlled by exciting the coil during motoring. The amount of power transmission is controlled to reach the two-speed command value, and the piston passes through a top dead center position where the piston is closest to the combustion chamber and a bottom dead center position where the piston is closest to the air spring chamber. In the meantime, the power transmission timing is controlled so as to stop the power transmission.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the control apparatus of the free piston type generator which can control the behavior of a piston more correctly than before.

It is a figure explaining the outline | summary of the free piston type electric power generation system which concerns on this embodiment. It is an expanded sectional view around a slit row. It is a figure explaining speed control concerning this embodiment. It is a figure which illustrates the starting method of the piston which concerns on this embodiment. It is a figure explaining the setting method of a speed command value. It is a figure explaining the change method of a speed command value.

<Overall configuration>
In FIG. 1, the outline | summary of the free piston type electric power generation system which concerns on this embodiment is shown. The free piston type power generation system includes a free piston type power generator 10 and its control device 18. The free piston generator 10 includes a cylinder 12, a piston 14, and a detector 16.

  A combustion chamber 20 is provided at one end of the cylinder 12 in the longitudinal direction, and an air spring chamber 22 is provided at the other end. The piston 14 is disposed in the cylinder 12 and reciprocates between the combustion chamber 20 and the air spring chamber 22 by the combustion pressure generated in the combustion chamber 20 and the repulsive force accompanying compression of the air spring chamber 22.

  A permanent magnet 24 is provided on the outer peripheral surface of the piston 14, and a coil 26 is wound around the inner peripheral surface of the cylinder 12 along the circumferential direction. As the piston 14 reciprocates, the permanent magnet 24 and the coil 26 move relative to each other. As a result, an induced electromotive force is generated to generate power.

  The free piston generator 10 is used as an electric motor when the free piston generator 10 is started, that is, in order to change the piston 14 from a stopped state to a reciprocating motion state. In this embodiment, the operation used as the electric motor includes initialization and motoring. The initialization is an operation of searching for an absolute value by moving the piston 14 when the absolute position of the piston 14 is unknown. Motoring refers to moving the piston 14 by applying an exciting current to the coil 26 after initialization, and the driving method of the piston 14 is a firing that moves the piston 14 by combustion pressure (explosion energy). There is a pair relationship.

  During power generation (firing), the control device 18 controls the behavior of the piston 14 by controlling the speed of the piston 14 energized by the combustion pressure or the repulsive force of the air spring chamber 22 by electric braking. To do. Further, at the start (during motoring), the behavior of the piston 14 is controlled by adjusting the excitation current flowing through the coil 26 and controlling the speed.

  The electric braking includes both dynamic braking that causes the generated power to be consumed by the resistor and regenerative braking that distributes the generated power to other electrical devices. In the present embodiment, at least one of power generation braking and regenerative braking may be performed.

<Details of each configuration>
The piston 14 is accommodated in the cylinder 12 and reciprocates in the cylinder 12. A slight clearance is provided between the piston 14 and the cylinder 12, and the piston 14 in the cylinder 12 can be moved while suppressing the gas flow between the combustion chamber 20 and the air spring chamber 22.

  In the example shown in FIG. 1, the piston 14 has a relatively small diameter on the combustion chamber 20 side and a relatively large diameter on the air spring chamber 22 side. By doing so, the pressure receiving area on the air spring chamber 22 side of the piston 14 is larger than the pressure receiving area on the combustion chamber 20 side, and even if the pressure in the air spring chamber 22 is relatively small, the piston 14 is placed in the combustion chamber. Can be pushed back to 20.

  Further, the piston 14 has an annular portion 28 formed on the outermost peripheral portion of the large diameter portion (air spring chamber side) so as to protrude toward the combustion chamber 20 side. The annular portion 28 is formed so as to be inserted into a guide ring groove 30 provided on the combustion chamber 20 side of the cylinder 12. The reciprocating movement (stroke) is stabilized when the piston 14 reciprocates while the annular portion 28 is inserted into the guide ring groove 30.

  In addition, as a further means for stabilizing the reciprocating movement of the piston 14, a blind hole 32 formed in the axial direction is formed on the back side of the small diameter portion of the piston 14, that is, on the air spring chamber 22 side. A guide shaft 34 extending from the air spring chamber 22 of the cylinder 12 is inserted into the blind hole 32.

  A permanent magnet 24 is provided on the outer peripheral surface of the large-diameter portion of the piston 14 including the annular portion 28, that is, the outermost peripheral surface of the piston 14. The permanent magnet 24 is preferably disposed so as to face the coil 26 in the entire stroke of the piston 14.

  By providing the permanent magnet 24 on the outer peripheral surface of the large-diameter portion relatively spaced from the combustion chamber 20, it becomes difficult to transfer heat from the combustion chamber 20 to the permanent magnet 24. As a result, the temperature of the permanent magnet 24 is increased. The accompanying demagnetization can be prevented.

  In addition to the permanent magnet 24, a slit row 35 is cut on the outer peripheral surface of the large-diameter portion of the piston 14 including the annular portion 28. In the example shown in FIG. 1, the slit rows 35 are cut above and below the paper surface of the piston 14, but the slit rows 35 may also be cut on both side surfaces. That is, on the outer peripheral surface of the piston 14, slit rows 35 may be cut around the circumference at intervals of 90 °. Further, these slit rows 35 may be formed so as to shift the phase. For example, you may make it cut the slit row | line | column 35 in each surface for every quarter of the space | interval of adjacent slits 37 and 37 (refer FIG. 2). By doing in this way, it becomes possible to detect the position of piston 14 with high precision.

  FIG. 2 shows an enlarged view of the slit row 35, that is, an enlarged view of a portion surrounded by a one-dot chain line circle in FIG. The slit row 35 is configured by cutting a plurality of slits 37 along the axial direction of the piston 14. Further, in the present embodiment, the feature portion 36 is provided such that the pitch (interval) between the adjacent slits 37 and 37 is different from other pitches. For example, in FIG. 2, a feature portion 36 having a pitch d2 different from the pitch d1 between the slits 37 and 37 is provided in the center portion of the slit row 35. In FIG. 1, the feature portion 36 is provided in the slit row 35 above and below the paper surface. However, the feature portion 36 may be provided in any one of a plurality of slit rows 35 formed around the circumference.

  The slit row 35 may be formed so as to face the detector 16 in the entire stroke of the piston 14. For example, when the piston 14 is at the top dead center (the position closest to the combustion chamber 20), the slit 37 on the rightmost side of the slit row 35 faces the detector 16, and the piston 14 is at the bottom dead center (most air). When in the spring chamber 22 side), the slit 37 on the leftmost side of the sheet of the slit row 35 is made to face the detector 16. In addition, it is preferable to form the feature portion 36 on the piston 14 so as to face the detector 16 when the piston 14 is located at the center of the stroke, that is, at the center of the cylinder length.

  Returning to FIG. 1, the cylinder 12 is a hollow substantially cylindrical member. The total length in the longitudinal direction of the hollow region, that is, the cylinder length is the stroke length, and the center position is the stroke center (origin). Further, the end of the stroke length becomes the stroke end. In accordance with the shape of the piston 14, the hollow shape of the cylinder has a relatively small diameter on the combustion chamber 20 side and a relatively large diameter on the air spring chamber 22 side.

  Along the reciprocating direction of the piston 14, in other words, a combustion chamber 20 is formed at one end in the cylinder length direction, and an air spring chamber 22 is formed at the other end. The combustion chamber 20 is provided with a scavenging hole 38, an exhaust port 40, an exhaust valve 42, an injector 44, and ignition means 46.

  The scavenging holes 38 introduce fresh air into the combustion chamber 20. When introducing fresh air, fresh air may be introduced into the scavenging holes 38 from the outside by driving a scavenging pump (not shown). The scavenging hole 38 may be opened, for example, on the inner wall surface of the cylinder 12. When the piston 14 is located at the top dead center, the scavenging hole 38 is blocked by the piston 14 and the piston 14 is located at the bottom dead center. Sometimes, it may be formed in a position where it is opened.

  Further, the exhaust port 40 discharges the exhaust after the mixture of fresh air and fuel is burned in the combustion chamber. Further, there may be a loop flow type in which scavenging / exhausting is performed only by the scavenging hole 38 without the exhaust port 40.

  The injector 44 is an injection unit that injects fuel. The ignition means 46 ignites the air-fuel mixture and generates combustion pressure. Further, the combustion pressure may be generated by a compression self-ignition method without the ignition means 46.

  The air spring chamber 22 has a function of pushing the piston 14 back to the combustion chamber 20 side. When the piston 14 moves from the combustion chamber 20 side to the air spring chamber 22 side, the air spring chamber 22 is compressed. A repulsive force is generated by this compression, and the piston 14 is pushed back to the combustion chamber 20 side by the repulsive force. In order to keep the internal pressure within a certain range, the air spring chamber 22 may be provided with a pressure regulating valve 48. Further, a pressure source such as a compressor may be connected to the air spring chamber 22 instead of the pressure regulating valve 48.

  The coil 26 is provided on the inner peripheral surface of the cylinder 12. The coil 26 is preferably provided at a position facing the permanent magnet 24 over the entire stroke of the piston 14. The coil 26 is connected to a power converter (not shown) such as an inverter provided outside. The AC power generated in the coil 26 is converted into DC power by a power converter and supplied to a DC power source such as a battery. Further, during initialization and motoring, DC power supplied from a DC power source is converted into AC power by a power converter and supplied to the coil 26.

  The detector 16 detects the displacement of the piston 14 by detecting the passage of the opposing slit row 35. Further, the feature portion 36 of the slit row 35 is detected. The detector 16 is provided together with the coil 26 on the inner peripheral surface of the large-diameter portion of the cylinder 12. As described above, the detector 16 is preferably provided at a position facing the slit row 35 over the entire stroke of the piston 14.

  The detector 16 may take two values depending on the unevenness of the slit 37. For example, when the detector 16 is opposed to the bottom surface of the slit 37, the detector 16 outputs a detection signal S1H. Further, when facing the protruding surface between the slits 37, the detector 16 outputs a detection signal S1L.

  A counter for counting the value of the detection signal S1 may be provided in the detector 16. For example, the counter may be configured by a hardware circuit in the detector 16. The counter is configured to increase each time the value (H / L) of the detection signal S1 increases, and the position of the piston 14 can be calculated based on this counter value. The counter value may be set so as to be reset when the feature portion 36 of the slit row 35 is detected. By this reset operation, the absolute position of the piston 14 can be detected. The counter value is transmitted to the control device 18.

  The detector 16 may be composed of any one of non-contact sensors such as an eddy current sensor, an optical sensor, and a capacitance sensor. In the cylinder 12, lubricating oil or the like adheres to the inner surface of the cylinder 12 or the outer surface of the piston 14, and it may be difficult to ensure an optically good detection environment. From such a viewpoint, it is preferable to use an eddy current sensor or a capacitance sensor as the detector 16.

  The control device 18 controls the behavior of the piston 14 in order for the free piston generator 10 to generate stable power. Further, at the time of initialization and motoring, the free piston generator 10 is caused to function as an electric motor, and the piston 14 is moved.

  The control device 18 may be composed of a computer. For example, a CPU that is an arithmetic circuit, a storage unit such as a memory, and a device / sensor interface are connected to each other via an internal bus. The storage unit stores a speed control program described later, and the speed control is performed by the CPU executing the program.

  The control device 18 exchanges signals with peripheral devices via the device / sensor interface. Specifically, the counter value is received from the detector 16, and the operation signal is transmitted to the exhaust valve 42, the injector 44, and the ignition means 46. When electric braking is performed, the power generation amount of the free piston generator 10 is controlled. For example, the supply destination (electric device, battery, resistor, etc.) of the generated power is selected. Further, the amount of exciting current supplied to the coil 26 is controlled during motoring.

<Piston control by speed control>
The control device 18 according to the present embodiment controls the behavior of the piston 14 based on speed control. The control device 18 determines the first speed command value in the expansion stroke in which the piston 14 is moved to the air spring chamber 22 side, and determines the second speed command value in the compression process in which the piston 14 is moved to the combustion chamber 20 side. .

  In the expansion stroke and compression process, speed control is performed so that the speed of the piston 14 becomes a predetermined speed command value. During power generation (firing), speed control is performed by electric braking. That is, the control device 18 controls the power generation amount so that the speed of the piston 14 reaches the first speed command value (expansion stroke) and the second speed command value (compression stroke). At start-up (motoring), speed control is performed by exciting current control. That is, the control device 18 controls the power transmission amount to the coil 26 so that the speed of the piston 14 reaches the first speed command value (expansion stroke) and the second speed command value (compression stroke).

  The speed of the piston 14 takes the lowest speed at the top dead center and the bottom dead center, and takes the highest speed at the center position of the stroke. Power generation braking and excitation are performed in accordance with such behavior.

  Since the relationship between the power generation amount, the braking amount of the piston 14, and the power transmission amount (excitation current amount) and the propulsion amount of the piston 14 is known, it is compared with the conventional piston control based on the energy balance with many disturbance elements. Thus, the speed control according to the present embodiment can control the behavior of the piston 14 with higher accuracy.

  The power generation braking and the excitation of the coil 26 as described above may be performed over the entire stroke of the piston 14, but the control may be executed only in a region where the speed control efficiency is relatively high. In general, when the piston 14 is near the top dead center or the bottom dead center, the speed of the piston 14 is low, and the power generation efficiency in this range and the propulsion efficiency due to the excitation current are relatively low. Therefore, for example, as shown by hatching in FIG. 3, while the piston 14 passes through the top dead center and the bottom dead center, the electric braking and the transmission of the excitation current are stopped (freely moved) and sent in other areas. The power transmission timing may be controlled so as to perform electricity. Here, the power change is shown in the lower part of FIG. The amount of power generation during firing (power generation) is indicated by a solid line, and the amount of power transmission during motoring is indicated by a broken line.

  The dispatch power area (and therefore the dispatch power suspension area) can be arbitrarily determined. For example, the area from the half value of the top dead center target position (middle position between the top dead center target position and the origin) to the half value of the bottom dead center target position (the middle position between the bottom dead center target position and the origin) The power generation area may be set. Further, an area within 90% of the maximum speed of the piston 14 may be set as an excitation area and a power generation area.

  At the start of motoring, when power transmission (excitation) is stopped near the top dead center and the bottom dead center as described above, the stop position of the piston 14 is close to the top dead center or the bottom dead center, and If it is attempted to move the piston 14 to the top dead center side or the bottom dead center side by motoring, the power transmission is suspended within a short period of time, and the bias of the piston 14 becomes insufficient.

  Therefore, as shown in FIG. 4, when the stop position of the piston 14 is known, the coil 26 is energized so as to bias the piston 14 to the side opposite to the stop position of the piston 14 when viewed from the stroke center position. It is preferable to control the excitation current. For example, when the stop position of the piston 14 is closer to the air spring chamber 22 (bottom dead center) when viewed from the stroke center position, the control device 18 moves the piston 14 to the combustion chamber 20 (top dead center) side. An exciting current is supplied to the coil 26 so that the

As another starting method, the moving region of the piston 14 may be limited to the excitation region excluding the vicinity of the top dead center and the bottom dead center as described above. In this case, it is preferable to adjust so that the piston 14 does not move to the top dead center and the bottom dead center by executing the speed control. For example, an amplitude proportional term gain k _pA , an amplitude integral term gain k _iA , an offset proportional term gain k _pO , and an offset integral term gain k _iO in speed control, which will be described later, are set to about 1/10 of a normal value.

<Generation of speed command wave>
As described above, in the speed control, the speed of the piston 14 is controlled to the first speed command value in the expansion stroke, and the second speed command value is controlled in the compression process. Therefore, as shown in FIG. 3, the speed command wave corresponding to the stroke of the piston 14 is a rectangular wave having the first speed command value and the second speed command value as peak values. The generation of this speed command wave will be described below.

  When setting the first and second speed command values, the control device 18 determines the first and second reciprocating cycles in the next reciprocating cycle based on the top dead center position and the bottom dead center position of the piston 14 in a predetermined reciprocating cycle. 2 Set the speed command value.

Specifically, as shown in FIG. 5, the difference between the predetermined top dead center target position and bottom dead center target position and the actual top dead center and bottom dead center in the (k−1) -th cycle is obtained. . When the difference ΔS _TDC between the top dead center target position and the actual top dead center and the difference ΔS _BDC between the bottom dead center target position and the actual bottom dead center are obtained, the controller 18 uses these values. The amplitude A of the speed command wave and the offset amount O from the speed 0 are obtained.

  The amplitude A of the speed command value can be obtained by the following mathematical formula (1). Further, the offset amount O of the speed command value can be obtained by the following mathematical formula (2). Based on the amplitude A and the offset amount O obtained by the mathematical formulas (1) and (2), the k-th cycle speed command wave (and hence the first speed command value and the second speed command value) is generated.

Here, k _pA in Equation (1) represents an amplitude proportional term gain, and k _iA represents an amplitude integral term gain. In addition, k _pO in Equation (2) represents an offset proportional term gain, and k _iO represents an offset integral term gain.

<Balance adjustment of speed command value>
As shown in FIG. 3, when the generated power in the expansion stroke and the compression stroke (transmitted power in motoring) is not uniform, the efficiency generally decreases when more power is generated. In addition, due to power non-uniformity, power transmission occurs during power generation, and conversely, power generation occurs during motoring (power transmission). In this embodiment, the target position of the bottom dead center is changed in order to alleviate the imbalance of power (generated power and transmitted power) in the expansion stroke and the compression stroke and to level the power in both strokes.

  In order to alleviate the electric power imbalance in the expansion stroke and the compression stroke, the bottom dead center target position may be adjusted. In general, the bottom dead center target position has a predetermined adjustment range (note that the top dead center position is related to the compression ratio for combustion control, and it is not possible to give the top dead center target position an adjustment range. Difficult). If the bottom dead center target position is lowered (moved toward the cylinder end), the moving distance of the piston 14 in the expansion stroke becomes relatively long, so that the electric braking force during the expansion stroke becomes relatively small (motor) As a result, the driving force becomes relatively large during the ring), and as a result, the generated power decreases (the transmitted power increases). On the other hand, since the piston 14 reaches the bottom dead center side, the energy stored in the air spring chamber 22 increases. Since this energy is released in the compression stroke, it is necessary to increase the power generation braking force accordingly. As a result, the generated power in the compression stroke increases (transmitted power decreases). That is, the power of the expansion stroke and the compression stroke is balanced.

  The adjustment of the bottom dead center target position is performed based on the following criteria, for example. When the integrated power generation amount controlled with the first speed command value is larger than the integrated power generation amount controlled with the second speed command value, the bottom dead center target position is separated from the stroke center position of the piston 14. Change as follows. In addition, when the integrated power generation amount controlled by the second speed command value is larger than the integrated power generation amount controlled by the first speed command value, the bottom dead center target position is set closer to the stroke center position of the piston 14. change. By making such a change, the absolute value difference between the first speed command value and the second speed command value is reduced, and the power of the expansion stroke and the compression stroke is balanced.

<Air spring chamber pressure cooperative control>
It is conceivable to increase the amount of fuel injected into the combustion chamber 20 with the aim of increasing the output. At this time, the combustion pressure increases and the piston 14 may collide with the end wall of the air spring chamber 22. Therefore, the air pressure (spring coefficient) in the air spring chamber 22 may be increased in accordance with the increase in combustion pressure. For example, a pressure source such as a compressor is connected to the air spring chamber 22. The control device 18 controls the pressurization source so as to increase the air pressure in the air spring chamber 22 so as to follow the increase in the combustion pressure.

<Other embodiments>
In the embodiment described above, the air spring chamber 22 is provided facing the combustion chamber 20, but the present invention is not limited to this configuration. In short, what is necessary is just to generate a repulsive force that pushes the piston 14 back to the combustion chamber 20 against the bias of the piston 14. For example, a spring chamber may be provided instead of the air spring chamber 22. Specifically, an elastic body is provided on the inner wall of the cylinder 12 perpendicular to the stroke direction of the piston 14. The elastic body may be a metal or resin processed into a spring shape (coil spring, disc spring). Further, the space constituting the air spring chamber 22 may be filled with an elastic body such as rubber. Further, a magnet chamber may be provided instead of the air spring chamber 22. For example, a magnet is provided on the mutually opposing surfaces of the piston 14 and the cylinder 12, and the repulsive force is used. The magnet may be a permanent magnet or an electromagnet. However, when it is difficult to provide power supply means for the piston 14, it is preferable to provide a permanent magnet for the piston 14. In addition, the air spring chamber 22 may be combined with at least one of the above-described spring, elastic body, and magnet. Further, a second combustion chamber may be provided instead of the air spring chamber 22.

  In addition, about adjustment of the spring coefficient according to the combustion pressure of the combustion chamber 20 mentioned above, what is necessary is just to provide the moving means which makes the position of the stroke direction of piston 14 variable, for example, if it is a spring or an elastic body. In the case of an electromagnet, the amount of current may be adjusted. Further, when the second combustion chamber is provided instead of the air spring chamber 22, the supply of the fuel to be injected into the second combustion chamber is coordinated with the change in the supply amount of the fuel to be injected into the combustion chamber 20. Adjust the amount.

10 Free Piston Generator, 12 Cylinder, 14 Piston, 16 Detector, 18 Control Device, 20 Combustion Chamber, 22 Air Spring Chamber, 24 Permanent Magnet, 26 Coil.

Claims (10)

A control device for a free piston generator, in which power is generated by reciprocating a piston in which a magnet is incorporated in a cylinder provided with a coil,
A combustion chamber is provided in the cylinder,
The controller is
Setting a first speed command value in an expansion stroke in which the piston is moved to the opposite side of the combustion chamber and a second speed command value in a compression stroke in which the piston is moved to the combustion chamber;
At the time of power generation, the amount of power generation is controlled so that the speed of the piston reaches the first and second speed command values by electric braking, or the speed of the piston is controlled by exciting the coil during motoring. 2 Control the amount of power transmission to reach the speed command value,
In setting the first and second speed command values, based on a top dead center position where the piston is closest to the combustion chamber and a bottom dead center position where the piston is farthest from the combustion chamber in a predetermined reciprocating cycle. A control device for a free piston generator, wherein the first and second speed command values in the next reciprocating cycle are set. A control device for a free piston generator according to claim 1,
The control device for a free piston generator, wherein the piston reciprocates between a combustion chamber provided in the cylinder and an air spring chamber. A control device for a free piston generator according to claim 2,
The control device determines the next difference based on the difference between the actual top dead center position and the top dead center target position and the difference between the actual bottom dead center position and the bottom dead center target position in a predetermined reciprocating cycle. A free piston type power generation characterized in that an amplitude of a speed command wave having a peak value of the first speed command value and the second speed command value and an offset amount from the speed 0 of the speed command wave in a reciprocating cycle of Machine control device. A control device for a free piston generator according to claim 2,
The said control apparatus reduces the absolute value difference of a 1st and 2nd speed command value by changing the said bottom dead center target position, The control apparatus of the free piston type generator characterized by the above-mentioned. A control device for a free piston generator according to claim 2 or 3,
The controller is
When the integrated power generation amount controlled with the first speed command value is larger than the integrated power generation amount controlled with the second speed command value, the bottom dead center target position of the piston is separated from the stroke center position of the piston. Change to
When the integrated power generation amount controlled with the second speed command value is larger than the integrated power generation amount controlled with the first speed command value, the bottom dead center target position of the piston is closer to the stroke center position of the piston. A control device for a free piston generator, wherein the control device is changed. A control device for a free piston generator according to any one of claims 2 to 4,
The said control apparatus increases the air pressure of the said air spring chamber with the increase in the combustion pressure in the said combustion chamber, The control apparatus of the free piston type generator characterized by the above-mentioned. A control device for a free piston generator according to any one of claims 2 to 5,
The control device controls the excitation current to the coil so as to bias the piston to the opposite side of the piston stop position when viewed from the stroke center position at the start of motoring. Control device for free piston generator. A control device for a free piston generator according to any one of claims 2 to 6,
The control device of the free piston generator, wherein the control device controls the dispatch power timing so that the dispatch power is stopped while passing through the top dead center position and the bottom dead center position of the piston. . A control device for a free piston generator according to claim 8,
In the motoring, the control device sets a region from a half value of the top dead center target position to a half value of the bottom dead center target position as an excitation region of the coil, and controls the free piston generator apparatus. A control device for a free-piston generator in which power is generated by reciprocating a piston incorporating a magnet between a combustion chamber and an air spring chamber in a cylinder provided with a coil,
The controller is
Setting a first speed command value in an expansion stroke in which the piston is moved to the air spring chamber side and a second speed command value in a compression stroke in which the piston is moved to the combustion chamber side;
At the time of power generation, the amount of power generation is controlled so that the speed of the piston reaches the first and second speed command values by electric braking, or the speed of the piston is controlled by exciting the coil during motoring. 2 Control the amount of power transmission to reach the speed command value,
The dispatch power timing is controlled so that the dispatch power is stopped while the piston passes the top dead center position where the piston is closest to the combustion chamber and the bottom dead center position where the piston is closest to the air spring chamber. A control device for a free piston generator.

Images