JP2017077144A - Linear generator and linear power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the weight, cost and loss in a linear generator, while reducing the resilience given to a needle externally.SOLUTION: A linear generator 10 includes a stator 26, and a piston 40, i.e., a needle arranged oppositely to the stator 26. One member out of the stator 26 and piston 40 has an iron core 27 and a winding, and the other member has a permanent magnet 43. Power is generated when the piston 40 moves in the linear direction for the stator 26. The piston 40 is configured to move so that the permanent magnet 43 is deviated, during use, from one end of the iron core 27 in the linear direction to the outside in the linear direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a linear generator and a linear power generation system that generate power by moving a mover in a linear direction with respect to a stator.

  Conventionally, a linear generator is known. The linear generator includes a stator and a mover, and the mover is disposed to face the stator. A permanent magnet is disposed on the mover, and a winding is disposed on the stator. When the mover moves in the linear direction with respect to the stator, the permanent magnet and the winding move relative to each other. The linear generator generates electricity by the induced electromotive force generated at this time.

  In Patent Document 1, a mover is coupled to a rod of a free piston engine (power source) that reciprocally moves in the axial direction, and the mover moves relative to an outer stator, thereby converting mechanical output to electrical power. A linear generator to convert is described. A return spring is coupled to the rod on the side opposite to the combustion chamber.

  Patent Document 2 describes a free piston device in which combustion gas expands in an expansion space in a piston chamber and the piston assembly is displaced in a linear direction by the gas. In this device, compressed gas is introduced into an elastic space in the piston chamber to provide a return force to the piston assembly. As the piston assembly moves, the armature (mover) moves, and electrical energy is generated by the relative movement between the armature and the stator.

  Patent Document 3 describes a configuration including a means for detecting displacement of a piston as a mover in a free piston generator. The means (displacement detection means) includes a plurality of grooves formed on the outer peripheral surface of the piston, a filling member filled in the grooves, and a displacement detector that is disposed on the cylinder member and detects the displacement of the grooves. The filling member is made of a material having a detection characteristic of the displacement detector different from that of the constituent material of the piston.

JP 2010-173630 A Special table 2009-541635 gazette JP2013-256886A

  In the techniques described in Patent Document 1 to Patent Document 3, when the stator is axially larger than the mover, when the stator includes a winding, the mover does not face the stator. Current flows through many winding arrangements. This can increase the copper loss of the winding. Moreover, when a stator contains an iron core, an iron loss may become large. In addition, in the stator, it is not used for the generation of the induced electromotive force in many parts of the windings, and the core and core that becomes the supporting part of the windings are large. It becomes. Furthermore, a dedicated means is required to give a restoring force when the mover is reciprocated. For example, the technique described in Patent Document 1 requires a spring as a dedicated means, which causes a further increase in weight and cost. In addition, the technique described in Patent Document 2 uses a dedicated gas compression mechanism for generating a restoring force, so that the efficiency is poor.

  An object of the present invention is to provide a structure capable of reducing weight, cost, and loss and reducing a restoring force applied to the mover from the outside in a linear generator and a linear power generation system.

  The linear generator according to the present invention includes a stator and a mover disposed to face the stator, and one member of the stator and the mover is disposed on the iron core and the iron core. A linear generator that generates electric power by moving the movable element in a linear direction with respect to the stator, the other member of the stator and the movable element including a permanent magnet. The mover is configured such that, in use, the mover moves so that the permanent magnet is disengaged from one end in the linear direction of the iron core to the outside in the linear direction.

  The linear power generation system according to the present invention includes the linear power generator according to the present invention and a control device that controls the linear power generator, and the mover is disposed in a cylinder having a combustion chamber and an air spring chamber. A free piston that reciprocates in a linear direction, and the control device includes a first speed command value in an expansion stroke in which the free piston moves toward the air spring chamber, and a compression in which the free piston moves toward the combustion chamber. The second speed command value in the stroke is set, and during power generation, the power generation amount is controlled so that the speed of the free piston becomes the first speed command value or the second speed command value by electric braking during power generation. The amount of power transmission is controlled by exciting the winding so that the speed of the free piston becomes the first speed command value or the second speed command value. The top dead center side moving time including when passing the top dead center position close to the combustion chamber, and the bottom dead center side including the time when the free piston passes the bottom dead center position closest to the air spring chamber The power transmission timing is controlled so as to stop the power transmission based on the travel time.

  According to the linear generator and the linear power generation system according to the present invention, the weight, cost, and loss can be reduced, and the restoring force applied from the outside to the mover can be reduced.

It is sectional drawing in the case where the piston which is a needle | mover is located in a top dead center in the linear electric power generation system containing the linear generator of embodiment which concerns on this invention. It is the A section enlarged view of FIG. In the linear generator shown in FIG. 1, it is sectional drawing which shows a state when a piston moves in a main operation area | region. In the linear generator shown in FIG. 1, it is sectional drawing in case a piston is located in a bottom dead center. In the linear electric power generation system of the embodiment concerning the present invention, it is a figure showing the dispatch electric field at the time of piston movement, and the speed command wave of a piston. It is a figure which shows the setting method of a speed command in the linear electric power generation system of embodiment which concerns on this invention. It is a mimetic diagram showing the basic composition of the embodiment concerning the present invention. In FIG. 7A, it is a schematic diagram which shows the state which attraction force acts on the permanent magnet of a piston by magnet magnetic flux. In another example of the linear generator of embodiment which concerns on this invention, it is a figure corresponding to FIG. 7A. In the linear generator of embodiment which concerns on this invention, it is a figure which shows the simulation result of the relationship between the protrusion amount e of the permanent magnet of the piston with respect to the iron core of a stator, and the axial direction thrust of the piston by magnet magnetic flux. It is a figure corresponding to FIG. 1 which shows the other example of the linear generator of embodiment which concerns on this invention. In the structure of FIG. 10, it is a schematic diagram which shows the state which the iron core core by the side of a mover moves to a several position with respect to the permanent magnet by the side of a stator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The shapes, materials, and numbers described below are illustrative examples and can be changed as appropriate according to the specifications of the linear generator. In the following, when a plurality of embodiments and modified examples are included, they can be implemented by appropriately combining them. In the following description, identical elements are denoted by the same reference symbols in all drawings. In the description in the text, the symbols described before are used as necessary.

  FIG. 1 is a cross-sectional view when a piston 40 that is a mover and a free piston is located at a top dead center in a linear power generation system including the linear generator 10 of the embodiment. FIG. 2 is an enlarged view of part A in FIG. FIG. 3 is a cross-sectional view showing a state when the piston 40 moves in the main operation region in the linear generator 10. FIG. 4 is a cross-sectional view of the linear generator 10 when the piston 40 is located at the bottom dead center.

<Configuration of power generation system and generator>
The free piston power generation system includes a linear generator 10 and a control device 50 that controls the linear generator 10. The linear generator 10 includes a cylinder member 20, a head member 21, and a piston 40. Hereinafter, the linear generator 10 is referred to as a generator 10.

  The cylinder member 20 is formed in a block shape having a cylinder 22 inside. The cylinder member 20 is formed of a nonmagnetic metal material such as aluminum or a nonmagnetic stainless alloy. One end (right end in FIG. 1) of the cylinder 22 in the axial direction (direction along the central axis O) which is the first linear direction opens to one end surface (right end surface in FIG. 1) of the cylinder member 20. The cylinder 22 has a small-diameter cylindrical surface S1 on the opening end side and a large-diameter cylindrical surface S2 on the bottom side. A piston 40 described later is fitted inside the cylinder 22 so as to be movable in the axial direction.

  A head member 21 is coupled and fixed to one end of the cylinder member 20. A combustion chamber 23 is formed in a space surrounded by one end of the piston 40 and the head member 21 in the inner space of the small-diameter cylindrical surface S1 of the cylinder member 20. In the cylinder member 20, an air spring chamber 24 is provided on the bottom side (the left side in FIG. 1) of the cylinder 22.

  An exhaust port 21 a is formed in the head member 21. The exhaust port 21 a communicates with the combustion chamber 23. By driving the exhaust valve 25 attached to the cylinder member 20, the combustion chamber 23 and the exhaust port 21a are closed or communicated. Other detailed structures of the cylinder member 20 will be described later.

  The piston 40 includes a columnar large-diameter portion 41 and a columnar small-diameter portion 42 connected to one end surface (the right end surface in FIG. 1) of the large-diameter portion 41. A cylindrical permanent magnet 43 is fixed to the outer peripheral surface of the large diameter portion 41. The permanent magnet 43 has an N pole on the air spring chamber 24 side and an S pole on the combustion chamber 23 side on the outer peripheral surface. The arrangement of the N and S poles may be reversed. A plurality of sets may be arranged in the axial direction of the piston 40 with the N pole and the S pole as one set.

  The large diameter portion 41 of the piston 40 is movably disposed inside the large diameter cylindrical surface S <b> 2 of the cylinder 22. The small diameter portion 42 of the piston 40 is movably disposed inside the small diameter cylindrical surface S <b> 1 of the cylinder 22. As a result, the piston 40 is disposed opposite to the inside of the stator 26 described later.

  The piston 40 reciprocates in the axial direction in the cylinder 22 by the combustion pressure generated in the combustion chamber 23 and the repulsive force accompanying the compression of the air spring chamber 24. A slight gap is provided between the piston 40 and the cylinder 22 to suppress the gas from flowing between the combustion chamber 23 and the air spring chamber 24, and the piston 40 in the cylinder 22 Allows movement. Since the piston 40 has the large diameter portion 41 and the small diameter portion 42 as described above, the pressure receiving area on the air spring chamber 24 side of the piston 40 is larger than the pressure receiving area on the combustion chamber 23 side. Thereby, even when the pressure of the air spring chamber 24 is relatively small, a repulsive force that pushes the piston 40 back toward the combustion chamber 23 is likely to occur.

  The linear generator 10 may be configured to include a mover displacement detection means (not shown). For example, as described in Patent Document 3, the mover displacement detection means may include a groove portion on the outer peripheral surface of the piston and a displacement detector disposed on the cylinder member. At this time, the groove portion may not be filled with the filling member, and the inside of the groove portion may be a gap.

  The displacement detector is composed of any one of non-contact sensors such as an eddy current sensor, an optical sensor, and a capacitance sensor.

  A stator 26 is fixed to the inner peripheral surface of the cylinder member 20. The stator 26 includes a substantially cylindrical iron core 27 and three-phase windings 28u, 28v, and 28w of U phase, V phase, and W phase disposed on the iron core 27. The iron core 27 is formed of a magnetic material such as iron and has a plurality of annular grooves on the inner peripheral surface. The plurality of grooves are arranged side by side in the axial direction of the iron core 27. The windings 28u, 28v, and 28w are arranged in the groove portion in the order of the U, V, and W phases, and this is repeated and arranged at a plurality of positions in the axial direction of the iron core 27. Each of the windings 28u, 28v, 28w is wound in the groove portion a plurality of times along the circumferential direction. Adjacent in-phase windings 28u, 28v, 28w may be arranged in reverse. Further, the axial length of the iron core 27 is larger than the axial length of the permanent magnet 47.

  The reciprocating movement of the piston 40 causes the piston 40 to move in the axial direction with respect to the stator 26, whereby the permanent magnet 43 moves relative to the windings 28u, 28v, 28w. Thereby, an induced electromotive force is generated and the generator generates power. Hereinafter, the windings 28u, 28v, and 28w may be collectively referred to as the winding 28.

  Furthermore, the piston 40 is configured such that, in use, the piston 40 moves so that the permanent magnet 43 is in a state of being detached from the axial end of the iron core 27 outward in the axial direction. More specifically, the piston 40 includes, in use, a main operation region in which the permanent magnet 43 is the entire axial range of the iron core 27, and one end side region and the other end side that are out of the main operation region on both sides. Configured to move to and from the area. As shown in FIGS. 1 and 2, the “one end side region” is a moving region that deviates from the main operation region to one axial end side (the right end side in FIG. 1). As shown in FIG. 4, the “other end side region” is a moving region that deviates from the main operation region to the other end side in the axial direction (left end side in FIG. 4). FIG. 3 shows a state where the permanent magnet 43 moves in the “main operation area”. In FIG. 1 to FIG. 4, “main operation area”, “one end side area”, and “other end side area” are shown as ranges in which the permanent magnet 43 moves. Since the permanent magnet 43 is configured to move outside the main operating region, the permanent magnet 43 moves from one axial end (right end in FIG. 1) to the axial outer side and the other axial end (see FIG. 1). It is configured to move from the left end) to the outside in the axial direction. Thereby, as will be described later, the weight, cost and loss of the generator 10 can be reduced, and the restoring force applied to the piston 40 from the outside can be reduced.

  Further, when the generator 10 is started, the generator 10 is operated as a motor in order to shift the piston 40 from the stopped state to the reciprocating state. At this time, the operation of the generator 10 as a motor includes an initialization operation and a motoring operation. The “initializing operation” is an operation for searching for an absolute value by moving the piston 40 when the absolute position of the piston 40 is unknown. “Motoring operation” means that the piston 40 is moved by passing an exciting current through the winding 28 after the initialization operation. As a driving method of the piston 40, the “motoring operation” is paired with “firing” in which the piston 40 is moved by combustion pressure (explosion energy).

  The control device 50 controls the behavior of the piston 40 by controlling the speed of the piston 40 energized by the combustion pressure, the repulsive force of the air spring chamber 24, and the like by electric braking during power generation (firing). To do. Further, at the start (during motoring operation), the behavior of the piston 40 is controlled by adjusting the excitation current flowing through the winding 28 and controlling the speed.

  “Electric braking” includes generation braking in which generated power is consumed by a resistor and regenerative braking in which generated power is distributed to other electric devices. In the embodiment, at least one of power generation braking and regenerative braking may be performed as electric braking.

  Further, a scavenging hole 29 (FIG. 4), an injector 30, and an ignition means 31 are provided in the combustion chamber 23 formed at one end of the cylinder member 20 in the axial direction.

  The scavenging holes 29 introduce new air into the combustion chamber 23. When introducing fresh air, the scavenging pump (not shown) may be driven to introduce fresh air into the scavenging holes 29 from the outside. The scavenging holes 29 are opened, for example, on the inner peripheral surface of the cylinder 22. As shown in FIGS. 1 and 2, when the piston 40 is located at the top dead center, the scavenging hole 29 (FIG. 4) is blocked by the piston 40. As shown in FIG. 4, when the piston 40 is located at the bottom dead center, the scavenging holes 29 are opened so as to communicate with the atmosphere.

  The exhaust port 21a discharges the exhaust gas after burning the mixture of fresh air and fuel in the combustion chamber 23 to the outside. A loop flow type in which the exhaust port 21a is omitted and the scavenging and exhausting is performed only by the scavenging holes 29 may be employed.

  The injector 30 is an injection unit that injects fuel. The ignition means 31 ignites the air-fuel mixture to generate a combustion pressure. The ignition means 31 can be omitted, and the combustion pressure can be generated by the compression auto-ignition method.

  The air spring chamber 24 has a function of pushing the piston 40 back to the combustion chamber 23 side. When the piston 40 moves from the combustion chamber 23 side to the air spring chamber 24 side, the air spring chamber 24 is compressed. A repulsive force is generated by this compression, and the piston 40 is pushed back to the combustion chamber 23 side by the repulsive force. In order to keep the internal pressure within a certain range, a pressure regulating valve may be provided in the air spring chamber 24. Further, a pressure source such as a compressor may be connected to the air spring chamber 24 instead of the pressure regulating valve.

  Winding 28 near the inner peripheral surface of cylinder 22 is connected to a power converter (not shown) such as an inverter provided outside. The AC power generated in the winding 28 during power generation is extracted outside, converted to DC power by a power converter, and supplied to a power storage device such as a battery. Further, during the initialization operation and the motoring operation, the DC power supplied from the power storage device is converted into AC power by the power converter and then supplied to the winding 28.

  The control device 50 controls the behavior of the piston 40 in order to cause the generator 10 to generate power stably. Further, during the initialization operation and the motoring operation, the generator 10 is operated as a motor, and the piston 40 is moved.

  The control device 50 includes a computer. For example, in a computer, a CPU that is an arithmetic circuit, a storage unit such as a memory, and an interface are connected to each other via an internal bus. The storage unit may store a control program for performing speed control and dispatch power suspension control, which will be described later. At this time, the control is performed by the CPU executing the program.

  The control device 50 transmits and receives signals to and from peripheral devices via the interface. Specifically, a detection signal is received from a position detector (not shown), and an activation signal for operating the exhaust valve 25, the injector 30, and the ignition means 31 is transmitted. When electric braking is performed, the power generation amount of the generator 10 is controlled. For example, the supply destination (electric device, power storage device, resistor, etc.) of the generated power is selected. During motoring control, the amount of excitation current supplied to the winding 28 is controlled.

<Speed control and dispatch power suspension control>
FIG. 5 is a diagram illustrating a shipping power region and a speed command wave of the piston 40 when the piston 40 moves in the linear power generation system of the embodiment. The control device 50 controls the behavior of the piston 40 based on the speed control. The control device 50 sets the first speed command value in the expansion stroke in which the piston 40 moves to the air spring chamber 24 side, and sets the second speed command value in the compression process in which the piston 40 moves to the combustion chamber 23 side.

  In the expansion stroke and the compression process, speed control is performed so that the speed of the piston 40 becomes a speed command value set in each. During power generation (firing), speed control is performed by electric braking. Specifically, the control device 50 controls the power generation amount so that the speed of the piston 40 reaches the first speed command value (expansion stroke) and the second speed command value (compression stroke), respectively. At the start (motoring operation), speed control is performed by exciting current control. Specifically, the control device 50 controls the amount of power transmitted to the winding 28 so that the speed of the piston 40 reaches the first speed command value (expansion stroke) and the second speed command value (compression stroke), respectively. To do.

  The speed of the piston 40 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.

  The power generation braking and the excitation of the winding 28 as described above may be performed over the entire stroke of the piston 40, but the control can be executed only in a region where the efficiency of the speed control is relatively high. In general, when the piston 40 is near the top dead center position or the bottom dead center position, the speed of the piston 40 is low, and the power generation efficiency and the propulsion efficiency by the excitation current in this range are relatively low. Therefore, preferably, as shown in FIG. 5, the control device 50 pauses the dispatching power during the top dead center side moving time including the time when the piston 40 passes the top dead center position (range of arrow α in FIG. 5). The power transmission timing is controlled as follows. Furthermore, the control device 50 controls the dispatch power timing so as to pause the dispatch power during the bottom dead center side moving time (in the range of arrow β in FIG. 5) including the time when the piston 40 passes the bottom dead center position. When the dispatching power is stopped, the electric braking and the transmission of the excitation current are stopped to move the piston 40 freely. And the control apparatus 50 can control dispatch electric power timing so that dispatch electric power may be performed in the area | region of the shaded part of FIG. Here, the power change is shown in the lower part of FIG. The power generation amount at the time of firing (power generation) is indicated by a solid line, and the power transmission amount at the time of motoring operation is indicated by a broken line.

  The dispatch power area and the dispatch power suspension area can be arbitrarily determined. For example, the region from the half value of the top dead center target position to the half value of the bottom dead center target position may be set as the excitation region and the power generation region of the winding. Further, an area within 90% of the maximum speed of the piston 40 may be set as an excitation area and a power generation area.

  Moreover, it is preferable to make the dispatch electricity suspension area correspond to when the permanent magnet 43 of the piston 40 moves in the one end side area and when it moves in the other end side area. Specifically, when the entire permanent magnet 43 of the piston 40 is in the main operation area, the dispatch power is sent in the dispatch power area, and when the permanent magnet 43 is in the one end side area or the other end side area, the dispatch power is dispatched. Turn off the power.

<Generation of speed command wave>
As described above, in the speed control, the speed of the piston 40 is controlled to the first speed command value in the expansion stroke, and is controlled to the second speed command value in the compression process. Thereby, the speed command wave corresponding to the stroke of the piston 40 becomes a rectangular wave having the first speed command value and the second speed command value as peak values, as shown in FIG. The generation of this speed command wave will be described below.

  FIG. 6 is a diagram illustrating a speed command setting method in the linear power generation system of the embodiment. When setting the first speed command value and the second speed command value, the control device 50 determines the first reciprocating cycle in the next reciprocating cycle based on the top dead center position and the bottom dead center position in the predetermined reciprocating cycle. 1 and the second speed command value are set.

Specifically, as shown in FIG. 6, 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 50 uses these values. Thus, the amplitude A of the speed command wave and the offset amount OS from the speed 0 are obtained.

  The amplitude A of the speed command value can be obtained by the following mathematical formula (1). Moreover, the offset amount OS of the speed command value can be obtained by the following mathematical formula (2). Based on the amplitude A and the offset amount OS obtained by the mathematical formulas (1) and (2), a speed command wave in the k-th cycle (thus, the first speed command value and the second speed command value) are 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.

<Effect>
According to the generator 10 described above, the axial end portions in the axial direction of the iron core and the winding are compared with the configuration in which the arrangement portion of the iron core and the winding is extended to the one end side region and the other end side region in the configuration of FIG. Can be omitted. Thereby, the weight and cost of the generator 10 can be reduced. Further, when the same-phase windings 28 are connected in series, currents of the same magnitude flow through the same-phase windings 28, so that the copper loss can be reduced by reducing the number of windings. Moreover, since the material of the iron core 27 can be reduced, iron loss can also be reduced. Thereby, the loss of the generator 10 can also be reduced. Furthermore, the restoring force given to the piston 40 from the outside can also be reduced. This will be described more specifically with reference to FIGS. 7A and 7B.

  FIG. 7A is a schematic diagram illustrating a basic configuration of the embodiment. FIG. 7B is a schematic diagram illustrating a state in which an attractive force is applied to the permanent magnet 43 of the piston 40 by the magnetic flux in FIG. 7A.

  In the embodiment, as shown in FIG. 7A, the piston 40 is movable so that the permanent magnet 43 fixed to the piston 40 (FIG. 1) jumps to one end region and the other end region on both sides of the main operation region. is there. At this time, as shown in FIG. 7B, the permanent magnet 43 protrudes from the iron core 27 to one end side in the axial direction (right side in FIG. 7B), and in the radial direction perpendicular to the axial direction of the permanent magnet 43, 27 does not oppose. A magnetic flux path is formed so that the magnetic flux emitted from the N pole of the permanent magnet 43 returns from the inner peripheral side of the iron core 27 to the S pole of the permanent magnet 43 through the outer peripheral side. And the permanent magnet 43 is pulled by the iron core 27 so that this magnetic flux path | route may become short. Thereby, an attractive force F in the axial direction toward the core core 27 acts on a portion of the permanent magnet 43 that protrudes from the core core 27. For this reason, since the restoring force is applied to the piston 40 by the magnetic flux, the restoring pressure applied from the outside to the piston 40 such as the combustion pressure in the combustion chamber 23 or electric braking can be reduced.

  In the embodiment, when the piston 40 moves to the air spring chamber 24 side, not only the repulsive force due to the compressed air in the air spring chamber 24 but also the attractive force due to the magnet magnetic flux can be applied to the piston 40. Thereby, since the pressure in the air spring chamber 24 can be lowered, the heat loss of the generator 10 can also be reduced.

  Further, unlike the technique described in Patent Document 1, there is no need to provide a spring for applying a restoring force to the piston 40, so that the weight and cost can be further reduced. Further, unlike the technique described in Patent Document 2, it is not necessary to provide a gas compression mechanism for generating a restoring force, so that the efficiency can be improved.

  In the case of the technique described in Patent Document 1, when a force is suddenly applied to the piston due to misfire or abnormal combustion in the combustion chamber, the control by the control unit cannot cope with the piston. There is a possibility of collision with the head. In the embodiment, even when the piston speed increases rapidly, the attraction force by the magnetic flux can be applied to the piston 40, so that such a collision can be prevented.

  In the configuration shown in FIG. 1 to FIG. 7B, the case where the piston 40 moves so that the permanent magnet 43 fixed to the piston 40 jumps out from the entire axial range of the iron core 27 of the stator 26 to both sides will be described. did. On the other hand, in the embodiment, the configuration is not limited to such a configuration, and the permanent magnet 43 moves to one end side region that is dislocated to one end side from the entire axial range of the iron core 27, but moves to the other end side region. You may comprise so that it may not. On the contrary, the permanent magnet 43 may move to the other end side region deviated from the entire axial range of the iron core 27 to the other end side, but may not be moved to the one end side region. Even in this case, the weight, cost and loss of the generator can be reduced, and the restoring force applied to the piston from the outside can be reduced.

  In the embodiment, as shown in another example of the generator shown in FIG. 8, in the stator 26, the cylindrical portion 26 a formed on the outer peripheral side at both axial ends of the iron core 27 is formed on the inner peripheral side of the iron core 27. It is good also as a structure which protrudes to an axial direction outer side from a part.

  FIG. 9 is a diagram illustrating a simulation result of the relationship between the protrusion amount e of the permanent magnet 43 of the piston 40 with respect to the iron core 27 of the stator 26 and the axial thrust of the piston 40 due to the magnetic flux in the generator of the embodiment. is there. As shown in FIG. 9, when the permanent magnet 43 jumps out of the iron core 27, an axial thrust (attraction force) due to magnet magnetic flux is generated in the piston 40 according to the pop-out amount e. This axial thrust pulsates finely due to a change in the positional relationship between the permanent magnet 43 and the stator 26. When the pop-out amount e becomes larger than a certain level, the axial thrust becomes small and becomes almost zero. In FIG. 9, the average value of the axial thrust is indicated by a broken line. Therefore, preferably, the maximum value of the pop-out amount e of the permanent magnet 43 is set to the pop-out amount corresponding to the positive peak of axial thrust pulsation. According to this, a large axial thrust can be applied to the piston 40 when the piston 40 is at the top dead center position or the bottom dead center position. Specifically, an axial thrust as an attractive force applied to the piston 40 by the magnetic flux according to the amount of protrusion of the permanent magnet 43, which is the amount of protrusion of the piston 40 from the main operation region, is considered. Then, a position where the outer end of the movable area of the permanent magnet 43, or the other end or both ends, is projected at a maximum (the amount of protrusion e) to the protruding position corresponding to the peak of the axial thrust pulsation obtained in advance from simulation or experiment. (Position where is the maximum). One or both of the top dead center position and the bottom dead center position of the piston 40 are set according to the outer end position of the movable region.

  In the example of FIG. 9, the maximum peak (portion surrounded by the broken line frame γ1) among the plurality of positive peaks in the axial thrust pulsation is the second largest peak (portion surrounded by the broken line frame γ2). ) On the side where the pop-out amount e is smaller. Therefore, it is determined as appropriate according to the magnitude of the thrust in the axial direction and the magnitude of the pop-out amount e, and either peak of γ1 or γ2 is selected according to the decision. Then, one or both of the top dead center position and the bottom dead center position of the piston 40 can be set according to the selected peak. When it is desired to make the pop-out amount e larger, the peak of the pulsation corresponding to the case where the pop-out amount e is larger, and the top dead center position of the piston 40 according to the third and subsequent large peaks. And one or both of the bottom dead center positions may be set.

  According to such a configuration, even when an abnormally large force is applied to the piston 40 for some reason, the piston 40 is based on the magnetic attractive force of the permanent magnet 43 immediately before the piston 40 collides with another member such as the cylinder member 20. A large deceleration force can be applied to the piston 40. Thereby, the collision of piston 40 can be prevented more effectively.

<Configuration of another example>
FIG. 10 is a diagram corresponding to FIG. 1 illustrating another example of the generator according to the embodiment. FIG. 11 is a schematic diagram showing a state in which the mover-side iron core 70 moves to a plurality of positions with respect to the stator-side permanent magnet 60 in the configuration of FIG. 10. 10 and 11, in the configuration shown in FIGS. 1 to 7B, a permanent magnet 60 is disposed as a stator on the cylinder member 20 side, and an iron core 70 on the piston 40 side. And the winding 71 (FIG. 11) is arranged.

  Specifically, in the cylinder member 20, a cylindrical permanent magnet 60 is fixed to the inner peripheral surface of the large-diameter cylindrical surface S2 of the cylinder 22. As shown in FIG. 11, the permanent magnet 60 has N poles and S poles alternately arranged in the axial direction (left and right direction in FIG. 11) on the inner peripheral surface. Moreover, the iron core 70 is fixed to the outer peripheral surface of the large diameter part 41 of the piston 40 (FIG. 10). The iron core 70 has a substantially cylindrical shape, and has a plurality of grooves arranged in the axial direction on the outer peripheral surface as shown in FIG. Then, the U-phase, V-phase, and W-phase three-phase windings 71 are arranged in order from the groove at one end in the plurality of grooves, and this is repeated. The axial length of the iron core 70 is larger than the axial length of the permanent magnet 60. In FIG. 10, the illustration of the groove portion and the winding 71 in the iron core 70 is omitted.

  The piston 40 is preferably formed of a nonmagnetic metal material such as aluminum. The reciprocating movement of the piston 40 causes the piston 40 to move in the axial direction with respect to the permanent magnet 60, thereby moving the winding 71 with respect to the permanent magnet 60. Thereby, an induced electromotive force is generated and the generator 10 generates power. The electric power obtained by power generation is taken out from the winding 71 of each phase of U, V, and W, and converted into DC power by a power conversion device (not shown) such as an inverter.

  Furthermore, when the piston 40 is used, as shown in FIGS. 10 and 11A, the permanent magnet 60 is moved outward from the axial end of the iron core 70 (the left end of FIGS. 10 and 11) in the axial direction. The piston 40 is configured to move so as to be in a detached state. In use, the piston 40 is in a state in which the permanent magnet 60 is disengaged from the other axial end of the iron core 70 (the right end in FIG. 11) outward in the axial direction, as shown in FIG. Thus, the piston 40 is configured to move. More specifically, when the piston 40 is in use, the one axial end T1 of the iron core 70 moves in the main operation region and in one end side region and the other end side region that are out of the main operation region on both sides. Configured. The “one end side region” is a moving region that deviates from the main operation region to one end side (the right end side in FIGS. 10 and 11). The “other end side region” is a moving region that deviates from the main operation region to the other end side (the left end side in FIGS. 10 and 11).

  The main operation area, the one end side area, and the other end side area will be described with reference to FIG. In FIG. 11, the maximum range in which one axial end (left end in FIG. 11) of the iron core 70 can move is defined as “full stroke”. The center range of all strokes is the “main motion area”, one end side area is set on the top dead center side (right side in FIG. 11), and the other end side is set on the bottom dead center side (left side in FIG. 11). An area is set.

  FIG. 11 shows a plurality of positions ((a) to (e)) of the iron core 70 when the piston 40 moves from the top dead center side to the bottom dead center side from (a) to (e). Yes. (C) is a case where the axial center of the permanent magnet 60 and the axial center of the iron core 70 coincide in the axial direction. From this state, when the iron core 70 moves to the top dead center side (the right side in FIG. 11), the axial one end T1 of the iron core 70 is aligned with the one axial end of the permanent magnet 60 (the left end in FIG. 11). It becomes the state (b) which matched in the direction. Further, in (a), one end in the axial direction of the permanent magnet 60 is out of the axial direction so that it protrudes from the one end T <b> 1 in the axial direction of the iron core 70. On the other hand, consider the case where the iron core 70 moves from the state (c) to the bottom dead center side (left side in FIG. 11). In this case, in (d), the other axial end T2 of the iron core 70 coincides with the other axial end (the right end in FIG. 11) of the permanent magnet 60 in the axial direction (d). Then, in (e), the permanent magnet 60 is in a state of being displaced outward in the axial direction so that the maximum protrusion amount e protrudes from the other axial end of the iron core 70.

In the configuration of FIG. 11, (a) shows the case where the permanent magnet 60 is in the one end side region, (b) to (d) show the case where the permanent magnet 60 is in the main operating region, and (e) shows the other end. The case where the permanent magnet 60 exists in the side area is shown. When the permanent magnet 60 is in the main operating region, the core core 70 includes a range that coincides with the entire axial direction of the permanent magnet 60 in the axial direction. When the permanent magnet 60 is in the one end side region, the iron core 70 is in the axial direction with respect to one end (the left end in FIG. 11) of the permanent magnet 60 so that it does not coincide with the entire axial direction of the permanent magnet 60 in the axial direction. It comes off to the other end side (right side in FIG. 11). When the permanent magnet 60 is in the region on the other end side, the iron core 70 is not aligned with the whole axial direction of the permanent magnet 60 in the axial direction with respect to the other end of the permanent magnet 60 (right end in FIG. 11). It comes off to one end side in the axial direction (left side in FIG. 11). Therefore, in use, the piston 40 has a state in which the permanent magnet 43 is disengaged axially outward from the axial end T1 of the iron core 27 and the permanent magnet 43 is axially outward from the axial other end T2 of the iron core 27. It is configured to move so as to be separated from each other.

  In the case of the configuration shown in FIGS. 10 and 11 as well, the weight, cost, and loss of the generator 10 can be reduced, and the restoring force applied to the piston 40 from the outside can be reduced as in the configurations of FIGS. Other configurations and operations are the same as the configurations of FIGS. 1 to 7B in which the iron core 27, the winding 28, and the permanent magnet 43 are arranged oppositely on the cylinder member 20 side and the piston 40 side, respectively. is there. 10 and 11, the iron core 70 moves so that the permanent magnet 60 is disposed in either the main operation region or the one end side region, but the permanent magnet 60 is disposed in the other end side region. You may comprise so that it may not be carried out. Conversely, the iron core 70 moves so that the permanent magnet 60 is disposed in either the main operation region or the other end region, but the permanent magnet 60 may not be disposed in the one end region. .

  10 and 11 may be combined with a configuration using the configuration described with reference to FIG. Specifically, the maximum value of the protrusion amount e of the permanent magnet 60 from the main operation region is set to the protrusion amount corresponding to the positive peak of the pulsation of the axial thrust applied to the piston 40 by the magnetic flux. At this time, the other end T2 or one end T1 or both ends, which are the outer ends of the movable region of the iron core 70, are placed at positions corresponding to the peak pulsation of the axial thrust according to the pop-out amount e of the permanent magnet 60. Position it as the maximum popping position. More specifically, the other end T2 or one end T1 of the iron core 70 is set such that the position at which the permanent magnet 60 protrudes from the iron core 70 at the maximum is the position at which the permanent magnet 60 protrudes with the protrusion amount e corresponding to the pulsation peak. Or position both ends. One or both of the top dead center position and the bottom dead center position of the piston 40 is set according to the outer end position of the movable region. According to this configuration, it is possible to more effectively prevent the piston 40 from colliding with another member.

  10 and 11, the axial length of the iron core 70 is larger than the axial length of the permanent magnet 60. However, the axial length of the iron core is larger than the axial length of the permanent magnet 60. It is good also as a small structure. In this configuration, the configuration in FIG. 1 is the same as the configuration in which the permanent magnet, the iron core, and the winding are replaced, and the main operation region is when the iron core is in the entire axial range of the permanent magnet. Further, the one end side region and the other end side region are regions that are separated from the main operation region toward the one end side in the axial direction and the other end side, respectively. In this case, a region where the permanent magnet has already deviated from the iron core is included in the main operation region. In this configuration, the amount of protrusion of the permanent magnet from the iron core increases due to the movement of the piston, so that an attractive force acts on the iron core so that the iron core is attracted to the permanent magnet. Thereby, the restoring force given to the piston from the outside can be reduced.

  In the configuration of each example described above, the case where the mover is the piston 40 of the free piston power generation system has been described. However, the mover may be a configuration including a permanent magnet or an iron core and a winding, and the mover may be The power source may be connected to a power source that reciprocates in the linear direction.

  DESCRIPTION OF SYMBOLS 10 Linear generator, 20 Cylinder member, 21 Head member, 21a Exhaust port, 22 Cylinder, 23 Combustion chamber, 24 Air spring chamber, 25 Exhaust valve, 26 Stator, 26a Cylindrical part, 27 Iron core, 28u U-phase winding , 28v V phase winding, 28w W phase winding, 29 scavenging hole, 30 injector, 31 ignition means, 40 piston, 41 large diameter portion, 42 small diameter portion, 43 permanent magnet, 50 control device, 60 permanent magnet, 70 iron core Core, 71 windings.

Claims (8)

A stator, and a mover disposed opposite to the stator,
Of the stator and the mover, one member includes an iron core and a winding disposed on the iron core,
Of the stator and the mover, the other member includes a permanent magnet,
A linear generator that generates electricity by moving the mover in a linear direction relative to the stator;
The mover is configured such that, in use, the mover moves so that the permanent magnet moves away from one end of the iron core in the linear direction to the outside of the linear direction. Machine. The linear generator according to claim 1,
The stator includes the iron core and the windings disposed on the iron core;
The mover includes the permanent magnet;
In use, the mover moves in a main operation area where the permanent magnet is the entire range of the iron core in the linear direction and to one end side area which is disengaged from the main operation area to one end side in the linear direction. Configured as a linear generator. The linear generator according to claim 2,
The movable element is configured such that, in use, the permanent magnet moves to the main operation region and the one end side region, and to the other end side region that is disengaged from the main operation region to the other end in the linear direction. , Linear generator. The linear generator according to claim 1,
The stator includes the permanent magnet;
The mover includes the iron core and the winding disposed on the iron core,
In use, the mover includes a main operation region including a range in which the iron core is coincident with the whole linear direction of the permanent magnet in the linear direction, and the iron core is the whole linear direction of the permanent magnet. Is a linear generator configured to move to one end side region deviating in the linear direction with respect to one end of the permanent magnet so as not to match in the linear direction. The linear generator according to claim 4,
When the mover is in use, the permanent magnet is configured so that the core core does not coincide with the main operation region and the one end side region, and the core core does not coincide with the entire linear direction of the permanent magnet in the linear direction. The linear generator comprised so that it may move to the other end side area | region which remove | deviates from the said linear direction with respect to the other end. The linear generator according to any one of claims 2 to 5,
The attraction force in the linear direction applied to the mover by the magnetic flux of the permanent magnet according to the amount of protrusion of the permanent magnet from the main operation region is set at a position corresponding to the peak of the pulsation of the attraction force. The linear generator in which the outer end of the movable region of the permanent magnet or the iron core is located. The linear generator according to any one of claims 2 to 6,
A linear generator in which the mover is a free piston that reciprocates in the linear direction in a cylinder having a combustion chamber and an air spring chamber. A linear generator according to claim 7;
A control device for controlling the linear generator,
The control device includes:
Setting a first speed command value in an expansion stroke in which the free piston moves toward the air spring chamber and a second speed command value in a compression stroke in which the free piston moves toward the combustion chamber;
During power generation, the amount of power generation is controlled by electric braking so that the speed of the free piston becomes the first speed command value or the second speed command value,
During motoring operation, the amount of power transmission is controlled so that the winding is excited and the speed of the free piston becomes the first speed command value or the second speed command value,
A top dead center side moving time including a time when the free piston passes the top dead center position closest to the combustion chamber, and a time when the free piston passes a bottom dead center position closest to the air spring chamber. A linear power generation system that controls the power transmission timing so as to stop the power transmission based on the bottom dead center side moving time.

Images