JP2019002341A - Engine control device - Google Patents

Abstract

Kind Code: A1 An engine control device prevents or suppresses the timing of changes in the operation of an engine in accordance with the operation of a gas compressor. An engine control device (100) adjusts a voltage applied to an electromagnetic coil (393) of a compressor (300) having an electromagnetic clutch (390) that switches between connection by energizing the electromagnetic coil (393) and disconnection by stopping energization of the electromagnetic coil (393). A compressor control unit 130 that performs control to control the compressor 300, a torque estimation unit 120 that estimates the driving torque of the compressor 300, and an engine 200 that is a power source that drives the compressor 300 according to the driving torque estimated by the driving torque estimation unit 120. The compressor control unit 130 and the engine control unit 110 are connected without a network such as CAN. [Selection drawing] Fig. 1

Description

  The present invention relates to an engine control device.

  A gas compressor of an air conditioning system (hereinafter referred to as an air conditioning system) mounted on a vehicle or the like operates by receiving power from an engine that is a power source of the vehicle or the like. In this case, an electromagnetic clutch is used to connect / disconnect the power supply from the engine. The electromagnetic clutch includes a rotor, an electromagnetic coil, and an armature. The rotor always rotates under the power of the engine, and the armature is connected to the rotating shaft of the gas compressor.

  The armature does not rotate because it is separated from the rotating rotor by a certain gap, but when the electromagnetic coil generates a magnetic force by energization, the armature is attracted to the rotor by the magnetic force and connected. Thereby, the armature rotates integrally with the rotor, and the rotating shaft connected to the armature rotates. Note that an elastic force of a spring member or the like acts on the armature, and when the electromagnetic coil is de-energized, there is no magnetic force for attracting the armature, and the armature is returned to a state separated from the rotor by this elastic force.

  As described above, the electromagnetic clutch is connected to and disconnected from the power source depending on whether or not a voltage is applied to the electromagnetic coil. However, when the armature is connected in contact with the rotor, the engine has a load of the gas compressor ( Torque) is applied suddenly. Since the engine is a drive source for driving the vehicle or the like, when a sudden load from the gas compressor is applied, the driving force of the vehicle is rapidly reduced, which may adversely affect the riding comfort.

  Here, a technique for reducing the torque at the time of starting the gas compressor by operating the cooling fan before starting the gas compressor has been proposed (for example, see Patent Document 1). According to this technique, since the torque at the time of starting of a gas compressor falls, the load which acts on a motive power source can be reduced.

  In addition, a technique has also been proposed in which an engine control device that controls the operation of the engine includes a torque estimation device that estimates the torque of the gas compressor when the gas compressor is started before the start (see, for example, Patent Document 2). ). The engine control device performs control to increase the engine driving force so as to compensate for the estimated torque in order to prevent the engine driving force from decreasing when the torque estimated by the torque estimating device acts on the engine. Do.

JP 2002-307938 A Japanese Patent No. 3912430

  The technique proposed in the above-mentioned prior art document 1 is not a technique that deals with a single gas compressor. That is, the technology of Prior Art Document 1 is a countermeasure in the cooling system, but if such a countermeasure is not taken in the cooling system, the countermeasure is to be taken on the electromagnetic clutch side of the gas compressor. Is desired. In this case, in order to control the electromagnetic clutch, a dedicated control device (hereinafter referred to as a gas compressor control device) is provided in the gas compressor.

  By the way, various control devices are mounted on a vehicle on which the above-described engine and gas compressor are mounted, and each control device is connected by a CAN (Controller Area Network). Since the CAN gives priority to the information that flows so that data (information) does not collide, there will be a delay depending on the status and priority of the information flow, and there will be a time lag in the control of both. There is.

  Therefore, the timing of the command to increase the output of the engine for compensating the torque of the gas compressor from the engine control device is from the timing of the command to start the gas compressor that reaches the gas compressor control device from the engine control device through CAN. May be too early. If the output of the engine increases prior to the generation of the load torque of the gas compressor, the vehicle may be accelerated instantaneously and affect the riding comfort. In particular, when the engine control device has a torque estimation device, the engine operation is caused by the above-described timing shift in spite of improving the accuracy of adjustment of the engine output corresponding to the torque of the gas compressor. There arises a problem that proper coordination between the gas compressor and the operation of the gas compressor is not possible.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an engine control device capable of preventing or suppressing the timing of change in the operation of the engine in accordance with the operation of the gas compressor. To do.

  The present invention relates to a gas compressor that performs control for adjusting power supplied to the electromagnetic coil of a gas compressor having an electromagnetic clutch that is switched between connection by energization of the electromagnetic coil and disconnection by stopping energization of the electromagnetic coil. A control unit, a torque estimation unit that estimates a driving torque of the gas compressor, and an output of an engine that is a power source that drives the gas compressor according to the driving torque estimated by the driving torque estimation unit. An engine control unit for controlling, and the gas compressor control unit and the engine control unit are engine control devices connected without a network.

  According to the engine control device of the present invention, it is possible to prevent or suppress the shift of the timing of the change in engine operation corresponding to the operation of the gas compressor.

1 is a block diagram illustrating a system that controls an engine including an engine control device (ECU) that is an embodiment of an engine control device according to the present invention and controls a compressor (gas compressor). It is sectional drawing which shows the compressor controlled by the compressor control part with which ECU of FIG. 1 was equipped. When the first control is performed by the compressor control unit, the voltage V applied to the electromagnetic coil with respect to the passage of time and the current I flowing through the electromagnetic coil by the application of the voltage are shown, and the clutch at the corresponding passage of time It is a diagram which shows a friction torque (torque of a rotor) and a compressor torque (torque of an armature). When the second control is performed by the compressor control unit, the voltage V applied to the electromagnetic coil with respect to the passage of time and the current I flowing through the electromagnetic coil by the application of the voltage are shown, and the clutch at the corresponding passage of time It is a diagram which shows a friction torque (torque of a rotor) and a compressor torque (torque of an armature).

  Hereinafter, an embodiment of an engine control device according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a system for controlling an engine 200 including an engine control unit (ECU) 100 that is an embodiment of an engine control unit according to the present invention, and controlling a compressor (gas compressor) 300. FIG. 2 is a sectional view showing a compressor 300 controlled by a compressor control unit 130 provided in the ECU 100 of FIG. The compressor 300 is of a vane rotary type as an example.

<ECU>
The ECU 100 includes an engine control unit 110, a torque estimation unit, and a compressor control unit 130 (gas compressor control unit). The engine control unit 110 controls the operation of the engine 200 that is a power source of the compressor 300.

  Torque estimation unit 120 estimates the drive torque of compressor 300. As this driving torque, for example, the torque of the compressor 300 corresponding to the combination of the rotation speed of the compressor 300 or the rotation speed of the engine and the refrigerant pressure on the high pressure (discharge) side of the compressor 300 is experimentally obtained in advance. The torque corresponding to the rotation speed and the refrigerant pressure is stored in the torque estimation unit 120 as a reference torque characteristic. Then, when a command to start the compressor 300 is input from the engine control unit 110, the torque estimation unit 120 refers to the reference torque characteristics with respect to the torque corresponding to the rotation speed of the compressor 300 and the refrigerant pressure at that time. The obtained torque is estimated as the driving torque of the compressor 300.

  It should be noted that since the compressor 300 has not been started when the command for starting the compressor 300 is input, the rotation speed of the compressor 300 becomes zero. However, the compressor 300 is connected to the engine via a pulley and is started. After that, the engine speed is multiplied by the pulley ratio. Therefore, when the start command is input, the compressor 300 does not actually rotate, but the torque estimation unit 120 calculates the rotation speed of the engine 200 when the command is input by multiplying the pulley ratio. The obtained rotation speed is regarded as the rotation speed of the compressor 300, and the drive torque is obtained based on the rotation speed, the refrigerant pressure, and the reference torque characteristics. The method for estimating the driving torque in the present invention is not limited to the above-described example.

  The engine control unit 110 outputs the output of the engine 200 when the compressor 300 is started in response to the driving torque of the compressor 300 estimated by the torque estimation unit 120 so that the driving force of the vehicle does not decrease due to the driving of the compressor 300. Increase. That is, when the compressor 300 is started, a load for driving the compressor 300 acts on the engine 200.

  The load of the compressor 300 is a driving torque of the compressor 300. And the driving torque of the compressor 300 is estimated by the torque estimation part 120 before starting. Therefore, engine control unit 110 controls the operation of engine 200 so that the output of engine 200 is increased by the amount of driving torque estimated by torque estimating unit 120 and the driving force of the vehicle does not decrease.

  The compressor control unit 130 controls the operation of the compressor 300, details of which will be described later. The compressor control unit 130 is incorporated in the ECU 100 integrally with the engine control unit 110 and the torque estimation unit 120.

<Compressor>
A compressor 300 shown in FIG. 2 is mounted on a vehicle and is configured as a part of an air conditioning system (hereinafter simply referred to as an air conditioning system) that performs cooling using the heat of vaporization of a cooling medium. A condenser, an expansion valve, an evaporator, and the like, which are constituent elements of the above, are provided on the cooling medium circulation path.

  The compressor 300 compresses the refrigerant gas G (gas) as a gaseous cooling medium taken from the evaporator of the air conditioning system, and supplies the compressed refrigerant gas to the condenser of the air conditioning system. The condenser heat-exchanges the compressed refrigerant gas with ambient air or the like to dissipate heat from the refrigerant gas and liquefy it, and sends it to the expansion valve as a high-pressure liquid refrigerant. The high-pressure liquid refrigerant is reduced in pressure by the expansion valve and sent to the evaporator. The low-pressure liquid refrigerant absorbs heat from the surrounding air and vaporizes in the evaporator, and cools the air around the evaporator by heat exchange accompanying the vaporization of the refrigerant. The vaporized low-pressure refrigerant gas G returns to the compressor 300 and is compressed, and the above process is repeated thereafter.

  The compressor 300 sucks the low-pressure refrigerant gas G into the interior, compresses the compressed gas to a high pressure and discharges it, a housing 310 that houses the compression mechanism 360, and a drive for driving the compression mechanism 360. And an electromagnetic clutch 390 for connecting and disconnecting power supply from an external power source.

  A space for accommodating the compression mechanism portion 360 is formed inside the housing 310. The compression mechanism 360 has a rotating shaft 351 lubricated with the refrigerating machine oil R, and the rotating shaft 351 rotates around the axis O to suck in the low-pressure refrigerant gas G and compress it to a high pressure. And discharged to the outside. Here, one end 351 a of the rotating shaft 351 is exposed to the outside of the housing 310.

<Electromagnetic clutch>
The electromagnetic clutch 390 includes a pulley 391, a rotor 392, an electromagnetic coil 393, an armature 394, and a hub 395. As shown in FIG. 2, the pulley 391 has a belt wound around an outer peripheral surface 391a formed with a plurality of grooves each having a V-shaped cross section along the circumferential direction. This belt is supplied with power from the engine 200 of the vehicle on which the compressor 300 is mounted.

  The rotor 392 is fixed to the housing 310 via a radial bearing, and can rotate about the rotation axis O. A cylindrical coil housing space is formed in the rotor 392, and a cylindrical electromagnetic coil 393 is housed in the coil housing space. The rotor 392 is integrated with the pulley 391. Therefore, when the pulley 391 is supplied with power from an engine or the like, the pulley 391 and the rotor 392 rotate around the axis O integrally.

  The electromagnetic coil 393 is fixed to the housing 310 via a yoke, does not rotate around the axis O, generates a magnetic force when energized, and disappears when the energization is stopped. The hub 395 is fastened to the end 351 a of the rotating shaft 351 exposed from the housing 310 by a screw 370. The leaf spring 396 can be elastically deformed along the direction of the axis O, and the armature 394 can be displaced with respect to the hub 395 within the range of this elastic deformation.

  The armature 394 is made of a material having a high coefficient of friction. The armature 394 is connected to the hub 395 via a leaf spring 396. The armature 394 is disposed through a slight gap from the side wall surface of the rotor 392 that is orthogonal to the axis O. When a magnetic force is generated by energizing the electromagnetic coil 393, the elasticity of the leaf spring 396 is generated by the magnetic force. The magnetic coil 393 is attracted against the force. When the armature 394 is displaced by this suction until the gap disappears (suction completion state), the armature 394 comes into contact with the side wall surface of the rotor 392. After the armature 394 and the side wall surface of the rotor 392 come into contact with each other, the armature 394 starts to rotate with the rotating rotor 392 due to an increase in frictional force (dynamic friction torque).

  As the dynamic friction torque between the armature 394 and the side wall surface of the rotor 392 increases, the speed difference (torque difference) between the armature 394 and the rotor 392 becomes smaller, eventually the speed difference becomes zero, and both rotate synchronously. (Consolidated state). Thereby, the compression mechanism part 360 of the compressor 300 in which the rotating shaft 351 is connected to the armature 394 is driven.

  On the other hand, when the energization to the electromagnetic coil 393 is stopped, the magnetic force generated by the electromagnetic coil 393 disappears. As a result, the armature 394 that is in contact with the side wall surface of the rotor 392 is rotated by the elastic force of the leaf spring 396. It is separated from the side wall surface of 392 and returned to its original position. Thereby, the armature 394 stops and the compression mechanism part 360 of the compressor 300 also stops.

<Compressor control unit>
Next, the compressor controller 130 that controls the operation of the compressor 300 by controlling the power supplied to the electromagnetic coil 393 will be described. The compressor control unit 130 adjusts the power supplied to the electromagnetic coil 393, such as applying a voltage to the electromagnetic coil 393 of the compressor 300, cutting the applied voltage, and adjusting the level of the applied voltage. To control the operation of the compressor 300. The compressor control unit 130 controls the operation of the compressor 300. The compressor control unit 130 is provided in the ECU 100 as described above, and is connected to the engine control unit 110 that is also provided in the ECU 100 via a network such as CAN. Without being connected directly.

  When the compressor control unit 130 receives an instruction for starting the compressor 300 (an instruction signal for applying a voltage to the electromagnetic coil 393) from the engine control unit 110, the compressor control unit 130 controls the voltage applied to the electromagnetic coil 393, thereby controlling the electromagnetic coil 393. A controlled voltage is applied.

  FIG. 3 shows the voltage V applied to the electromagnetic coil 393 over time and the current I flowing in the electromagnetic coil 393 due to the application of the voltage when the compressor control unit 130 performs the first control. FIG. 5 is a diagram showing a clutch friction torque (rotor 392 torque) and a compressor torque (armature 394 torque) in a corresponding time lapse.

  Further, FIG. 4 shows the voltage V applied to the electromagnetic coil 393 with respect to time and the current I flowing through the electromagnetic coil 393 when the second control is performed by the compressor control unit 130. FIG. 4 is a diagram showing a clutch friction torque (rotor 392 torque) and a compressor torque (torque of armature 394) in a corresponding time passage. 3 and 4, the clutch friction torque is indicated by a solid line, and the compressor torque is indicated by a one-dot chain line.

  When the voltage V1 is applied to the electromagnetic coil 393 from the state where the armature 394 is separated from the rotor 392 (the state before starting the compressor 300) (clutch activation in FIGS. 3 and 4), even if the voltage V1 is constant, the electromagnetic coil The current value of the current I <b> 1 flowing through 393 increases with time, and then the current value of the current I <b> 1 flowing through the inductance change of the electromagnetic coil 393 decreases. Then, after the elapse of time t <b> 1 from the start of the electromagnetic clutch 390, the suction is completed when the armature 394 starts to contact the side wall surface of the rotor 392. Note that the state of completion of suction does not reach a state where the connection between the armature 394 and the side wall surface of the rotor 392 has been completed because the slip has occurred.

  Since the current I2 sufficient to connect the armature 394 to the rotor 392 continues to be supplied to the electromagnetic coil 393 from the completion of the suction, the slip between the armature 394 and the side wall surface of the rotor 392 over time t Accordingly, the clutch friction torque (rotor 392 torque) and the compressor torque (armature 394 torque) increase. After the passage of time t2 from the completion of the suction, the slip between the armature 394 and the side wall surface of the rotor 392 is eliminated, and the clutch friction torque and the compressor torque match in a completed connection state in which both rotations coincide (synchronize).

  Even after the connection is completed, by continuing to supply the current I to the electromagnetic coil 393, the connection state of the electromagnetic clutch 390 is maintained. However, the supply of the current I is stopped or the current I is less than a certain value (the armature 394 is turned into the rotor). When the current is reduced to less than a current sufficient to be coupled to 392, the armature 394 is separated from the side wall surface of the rotor 392, and the electromagnetic clutch 390 is disconnected.

  When the load of the compressor 300 at the time of startup estimated by the torque estimation unit 120 is relatively high, the compressor control unit 130 performs the first control shown in FIG. When the load of the compressor 300 at the time of starting is relatively low, the second control shown in FIG.

The first control described above by the compressor control unit 130 is specifically the control shown in the following (1).
(1) When a start signal is input from the engine control unit 110, a relatively high voltage V1 necessary for flowing a relatively high current I1 to the electromagnetic coil 393 is applied as a voltage to be applied to the electromagnetic coil 393. To do.

  Note that since the rotation speed of the compressor 300 at the moment of start-up is zero, the rotation speed of the engine 200 corresponding to the rotation speed of the compressor 300 is input to the compressor control unit 130 when the electromagnetic clutch 390 is completely connected. Thus, the compressor control unit 130 calculates the rotation speed of the compressor 300 based on the input rotation speed of the engine 200. Hereinafter, the same applies to the second control.

  That is, the first control is a control in which a relatively high constant voltage V1 for flowing a relatively high current I1 is continuously applied to the electromagnetic coil 393 from the start to the end of connection. .

Specifically, the second control described above by the compressor control unit 130 is the control shown in the following (2).
(2) When an activation signal is input from the engine control unit 110, the voltage applied to the electromagnetic coil 393 is a relatively low current to the electromagnetic coil 393, which is sufficient to connect the armature 394 to the rotor 392. A relatively low voltage V2 (V1) necessary for flowing a current I2 is applied.

  Specifically, the second control is a relatively high constant voltage V1 for causing a relatively high current I1 to flow through the electromagnetic coil 393 from the start of the electromagnetic clutch 390 to the completion of suction (when time t1 has elapsed). Apply. This relatively high voltage V1 is the same voltage as the voltage V1 in the first control.

  From the completion of the subsequent suction to the completion of connection (time t2 elapses), a current I2 that is lower than the first high current I1 and sufficient to connect the armature 394 to the rotor 392 is passed through the electromagnetic coil 393. The required relatively low voltage V2 (<V1) is applied. At this time, the current I2 flowing through the electromagnetic coil 393 is lower than the current I2 flowing through the electromagnetic coil 393 in the first control.

  Therefore, the magnetic force generated by the electromagnetic coil 393 in the period from the completion of the suction by the second control to the completion of the connection is lower than the magnetic force generated by the electromagnetic coil 393 in the period from the completion of the suction by the first control to the completion of the connection. It becomes. As a result, as shown in FIGS. 3 and 4, the time t2 from the completion of suction by the second control to the completion of connection becomes longer than the time t2 from the completion of suction by the first control to the completion of connection. This prevents or suppresses the load of the compressor 300 from acting suddenly (within a short time).

  Further, in the second control, after the armature 394 and the rotor 392 are connected to rotate integrally, the voltage V applied to the electromagnetic coil 393 is switched to a relatively high voltage V3. As a result, even if there is some torque fluctuation in the electromagnetic clutch 390 in the connected state, the suction force is increased compared to that before the connected state, so that the unintentional release of the connected state is prevented or suppressed. be able to.

  Here, the voltage V3 is the same as the first relatively high voltage (voltage in the first control) V1. In addition, instead of accurately detecting the connection completion state each time, the time t2 when the connection is completed is obtained experimentally in advance, and the time obtained experimentally in advance by taking into account each error and the like. A time (t2 + Δt) obtained by adding a time Δt that can absorb an error or the like to t2 is stored in the compressor control unit 130, and it is estimated that the connection is completed when the time (t2 + Δt) has elapsed. The applied voltage V is switched from V2 to V3.

  According to the ECU 100 configured as described above, the engine control unit 110 outputs a command for starting the compressor 300 to the torque estimation unit 120 in order to operate the air conditioning system. The torque estimation unit 120 receives this command, estimates the driving torque of the compressor 300, and outputs the estimated driving torque to the engine control unit 110 and the compressor control unit 130.

  The compressor control unit 130 switches between performing the above-described first control or the second control in accordance with the estimated torque input from the torque estimation unit 120. That is, when the estimated torque is higher than the preset torque, the compressor control unit 130 selects the first control that keeps the voltage applied to the electromagnetic coil 393 constant, and the estimated torque is When the torque is equal to or lower than the preset torque, the second control is selected in which the voltage applied to the electromagnetic coil 393 is decreased after completion of the suction and increased again after the completion of the connection. Whether the first control or the second control selected by the compressor control unit 130 is output to the engine control unit 110.

  The engine control unit 110 increases the output of the engine 200 based on the estimated driving torque input from the torque estimation unit 120 and the first control or the second control input from the compressor control unit 130. And a start command is output to the compressor control unit 130. The control of the increase in output to the engine 200 at this time is adjusted so as to coincide with the completion timing of the suction after the electromagnetic clutch 390 of the compressor 300 is activated.

  As described above, the ECU 100 of the present embodiment includes the engine control unit 110 and the compressor control unit 130, and inputs and outputs information such as commands between the engine control unit 110 and the compressor control unit 130. Directly without going through a network such as CAN. Therefore, the timing of the control of the engine 200 by the engine control unit 110 and the timing of the control of the compressor 300 by the compressor control unit 130 do not deviate depending on the network conditions. Therefore, it is possible to prevent or suppress the occurrence of a shift between the timing at which the output of engine 200 begins to increase and the timing at which the torque starts rising from zero after the electromagnetic clutch 390 has been sucked.

  Further, according to the ECU 100 of the present embodiment, in the second control of the compressor control unit 130, the rotor 392 is applied to apply the voltage V1 higher than the voltage V2 applied from the completion of the suction to the completion of the connection before the suction is completed. It is possible to generate a suction force sufficient to displace the armature 394 away from the armature 394 in the direction in which the armature 394 is attracted to the rotor 392 against the elastic force of the leaf spring 396.

  The ECU 100 of the present embodiment has a configuration in which the torque estimation unit 120 is independent of the engine control unit 110, but the torque estimation unit 120 may be configured as a part of the engine control unit 110 inside the engine control unit 110. Good. Similarly, the compressor control unit 130 is configured independently of the engine control unit 110, but the compressor control unit 130 may be configured as a part of the engine control unit 110 inside the engine control unit 110.

  The ECU 100 according to the present embodiment switches the voltage applied to the electromagnetic coil 393 by the compressor control unit 130 between two types (high and low) (or switches between three types including the state where no voltage is applied). The compressor control unit may be one that does not switch the voltage applied to the electromagnetic coil (switches it from the state where it is not applied). Moreover, the gas compressor control part of the engine control apparatus which concerns on this invention may switch the voltage applied to an electromagnetic coil into 3 or more types (it switches to 4 or more types including the state which is not applied). Furthermore, the gas compressor control part of the engine control apparatus according to the present invention may be configured such that the voltage applied to the electromagnetic coil can be set to an arbitrary height between high and low.

  Although the compressor 300 of this embodiment is a vane rotary type gas compressor, the gas compressor controlled by the gas compressor control unit of the engine control device according to the present invention is a gas compression provided with an electromagnetic clutch. As long as it is a machine, a gas compressor other than the vane rotary type may be controlled. Therefore, the engine control apparatus according to the present invention is also applied to an engine control apparatus that controls a swash plate type gas compressor other than the vane rotary type, a scroll type gas compressor, or the like.

100 ECU (Engine Control Unit)
110 Engine control unit 120 Torque estimation unit 130 Compressor control unit 200 Engine 300 Compressor (gas compressor)
390 Electromagnetic clutch 392 Rotor 393 Electromagnetic coil 394 Armature O Axis center

Claims (3)

A gas compressor control unit that performs control to adjust power supplied to the electromagnetic coil of a gas compressor having an electromagnetic clutch that is switched between connection by energization to the electromagnetic coil and disconnection by stopping energization of the electromagnetic coil;
A torque estimation unit for estimating a driving torque of the gas compressor;
An engine control unit that controls an output of an engine that is a power source for driving the gas compressor according to the driving torque estimated by the torque estimation unit,
The gas compressor control unit and the engine control unit are engine control devices that are connected without a network. When a command to supply power to the electromagnetic clutch is input, the gas compressor control unit generates a voltage necessary to flow a current sufficient to connect the armature of the electromagnetic clutch to the rotor of the electromagnetic clutch. After supplying to the electromagnetic coil and connecting the armature to the rotor, a voltage higher than a voltage necessary to flow a current sufficient to connect the armature to the rotor is supplied to the electromagnetic coil. The engine control apparatus according to claim 1, which controls the engine. When a command to supply power to the electromagnetic clutch is input, the gas compressor control unit has a current sufficient to connect the armature to the rotor until the armature is attracted to the rotor. The engine control apparatus according to claim 2, wherein control is performed so that a voltage higher than a voltage necessary for flowing the current is supplied to the electromagnetic coil.