JP2017120028A - Engine and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine and a method for controlling the same which can avoid abnormal noise or abrasion caused by slippage of a belt for driving an auxiliary machine and can surely restrain deterioration of the belt when rotational power from the engine is transmitted to the auxiliary machine through a power transmission mechanism so as to drive the auxiliary machine.SOLUTION: An engine includes a control device 30 which inputs and outputs a signal among a crank angle sensor 31, an accelerator opening sensor 35, and a generator 14. The control device 30 monitors an operation state of an engine 10 based on an engine speed Ne and an accelerator opening Ap, and controls to decrease a power generation amount Pm of the generator 14 when it is determined that the operation sate is in a slip increase region A1 in which occurrence or increase of slippage of a belt 23 is predicted.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an engine and a control method thereof, and more particularly, to an engine and a control method thereof that suppress deterioration of a belt by reducing abnormal noise and wear caused by slipping of a belt that drives an auxiliary machine.

  In the engine, the rotational power of the engine is transmitted from the driving pulley fixed to the crankshaft to the driven pulley fixed to the output shaft of the auxiliary machine via the endless belt, thereby driving the auxiliary machine. . Examples of the auxiliary machine include a generator (alternator), a water pump, an air compressor, a coupling fan, and a hydraulic pump.

  When driving these auxiliary machines, there is a problem that the belt slips when the rotational fluctuation of the engine is large or when the load applied to the belt is large. As described above, when the belt slips, the belt slip noise increases or the belt wears, and the belt progresses further.

  In this regard, there have been proposed a device that reduces the output of the auxiliary machine when the crank angular speed increases rapidly, and a device that reduces the output of the auxiliary machine when a belt slip is detected (see, for example, Patent Documents 1 and 2). In these devices, by reducing the output of the auxiliary machine, an increase in the slip of the belt is avoided and the deterioration of the belt is suppressed.

  However, since the device described in Patent Document 1 detects the sudden increase of the crank angle, and the device described in Patent Document 2 detects the slip of the belt, the output of the auxiliary machine is reduced. Response delay occurs until the output of the auxiliary machine decreases. For this reason, there is a problem that belt slippage occurs, and belt slippage cannot be completely avoided.

JP 59-1119028 JP 2005-185066 A

  The object of the present invention is to prevent the occurrence of noise and wear caused by slipping of the belt driving the auxiliary machine in advance with simpler control, and to reliably suppress belt deterioration. An engine and a control method thereof are provided.

An engine of the present invention that achieves the above object includes a driving pulley that is fixed to a crankshaft, a driven pulley that is fixed to a drive shaft of an auxiliary machine whose output value is adjustable, and these driving pulley and driven In an engine having a power transmission mechanism comprising an endless belt wound around a pulley, a rotation speed detection device for detecting an engine rotation speed, which is the rotation speed of the crankshaft, and an accelerator opening degree of an accelerator pedal are detected. An opening degree detection device, and a rotation number detection device, an opening degree detection device, and a control device that inputs and outputs signals between the auxiliary devices, the control device, the engine rotation speed and the The operation state of the engine is audited based on the accelerator opening, and the operation state is in a slip increase region where the belt slip is predicted to occur and increase in advance. If it is determined, it is characterized in that it is configured to perform control to decrease the output value of the accessory.

  In addition, the engine control method of the present invention that achieves the above-described object provides a drive shaft of an auxiliary machine that is configured such that an output value can be adjusted via an endless belt from a driving pulley fixed to a crankshaft. In a method for controlling an engine that transmits rotational power to a driven pulley that is fixed and drives an auxiliary machine thereof, the step of acquiring the operating state of the engine, and the acquired operating state of the engine in advance indicate that the belt slips. Determining whether it is in a slip increase region predicted to occur and increase, and decreasing the output value of the accessory when it is determined that the operating state of the engine is in the slip increase region; The method characterized by including.

  Auxiliary machines with adjustable output values here include variable voltage generators (alternators), inverter controlled generators, variable capacity (for example, swash plate type) water pumps, variable capacity, etc. Air clutches, fan clutch type coupling fans made of viscous or fluid couplings, variable capacity type hydraulic pumps, and the like.

  Therefore, the control (step) for reducing the output value of the auxiliary machine is exemplified by the control for reducing the power generation amount by the inverter when the auxiliary machine is a generator. Moreover, when an auxiliary machine is a water pump, control which reduces the discharge flow volume of the cooling water discharged from a water pump is illustrated. Moreover, when an auxiliary machine is an air compressor, control which reduces the discharge flow rate of the compressed fluid discharged from an air compressor is illustrated. Moreover, when an auxiliary machine is a coupling fan, control which reduces the air volume of a coupling fan is illustrated. When the auxiliary machine is a hydraulic pump, control for reducing the discharge flow rate of oil discharged to the hydraulic pump is exemplified.

  The operating state of the engine means the engine speed and the accelerator opening (or output torque or fuel injection amount based on the accelerator opening). That is, the operating state of the engine can be determined using a performance characteristic diagram based on the engine speed and the accelerator opening.

  Further, the slip increase region is a region where belt slip is predicted to occur and increase when the output value of the auxiliary machine is kept at the set value. This slip increase region is preferably set in advance on the performance characteristic diagram through experiments and tests. This slip increase region will be described more specifically. The region existing along the performance characteristic curve on the low rotation side where the engine speed is low in the performance characteristic diagram, and the high opening side where the accelerator opening is high in the performance characteristic diagram. A region existing along the performance characteristic curve is preferably exemplified. In other words, the region existing along the performance characteristic curve on the low rotation side in the performance characteristic diagram is a region where the engine rotational fluctuation is large. Further, the region existing along the performance characteristic curve on the high opening degree side in the performance characteristic diagram is a region where the engine load is large and the load applied to the belt is large.

  Note that the belt slip here does not occur constantly throughout the engine operating range due to belt tension reduction or wear and other deterioration, but when the engine rotational fluctuation is large or the load applied to the belt. This occurs when is large.

  According to this engine and its control method, paying attention to the fact that a belt slip occurs and increases according to the engine operating state, the engine operating state is predicted to generate and increase a belt slip in advance. When it is in the area, the output value of the auxiliary machine is reduced in advance.

More specifically, before the belt slip occurs and increases according to the operating state of the engine, the output value of the auxiliary machine is reduced in advance, thereby reducing the load on the auxiliary machine. As a result, in the low speed region where the engine rotational fluctuation is large, the load on the auxiliary machine is reduced, so that the auxiliary machine can follow the rotational fluctuation, thereby preventing the occurrence and increase of the belt slip. . Similarly, even in a high opening region where an excessive load is applied to the belt, an excessive load applied to the belt is reduced by reducing the load on the auxiliary machine, so that the occurrence and increase of the belt slip can be avoided.

  In other words, by avoiding the occurrence of abnormal noise and wear due to belt slip in advance, response delay until the load on the auxiliary machine actually decreases is avoided, so belt degradation is ensured. Can be suppressed.

  Further, by avoiding the occurrence and increase of belt slip, the auxiliary machine can be reliably driven by the rotational power transmitted from the crankshaft, so that the output value of the auxiliary machine can be brought close to the target value. In other words, fuel efficiency deteriorates due to a decrease in the amount of power generated by the generator due to belt slip, malfunction of the electric auxiliary machinery, insufficient cooling of the engine due to a decrease in the discharge flow rate of the water pump and a decrease in the air volume of the coupling fan, Insufficient pressure accumulation in the air tank due to a decrease in the discharge flow rate of the compressor, an increase in discomfort due to the inability to control the cabin temperature due to a decrease in the discharge flow rate of the air compressor, and a malfunction of hydraulic equipment due to a decrease in the discharge flow rate of the hydraulic pump, etc. Can be avoided.

It is a block diagram which illustrates the engine of embodiment of this invention. It is a flowchart which illustrates the control method of the engine of embodiment of this invention. It is a performance characteristic figure of an engine which illustrates a slip increase field. It is a flowchart which illustrates the detail of step S40 of FIG. It is a correlation diagram which illustrates the correlation with the output value of an auxiliary machine, and the rotation speed of a driven pulley. It is a correlation diagram which illustrates the correlation with each parameter and the reduction | decrease amount of the output value of an auxiliary machine. It is a performance characteristic figure of an engine which illustrates an expanded slip increase field.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 illustrates an engine 10 according to an embodiment of the present invention. The engine 10 drives a generator (alternator) 14 by rotational power transmitted from a crankshaft 13 through a power transmission mechanism 20.

  In this embodiment, the generator 14 with an adjustable voltage Vm output by the voltage regulator 36 is exemplified as an auxiliary machine. However, as an auxiliary machine, in addition to the generator 14, a variable capacity type (for example, A water pump of a swash plate type, a variable capacity type air compressor, a fan clutch type coupling fan composed of a viscous or fluid coupling, a variable capacity type hydraulic pump, and the like are exemplified. Further, the number of auxiliary machines is not limited to one, but may be some combinations of the exemplified apparatuses or all of them. Further, the generator 14 may be one capable of applying a driving force to driving wheels such as an inverter-controlled motor generator in a hybrid vehicle.

  In the engine 10, the fuel injected from the fuel injection valve 12 in the cylinder 11 burns to generate thermal energy, and the crankshaft 13 is rotated by the thermal energy. This rotational power drives the drive wheels via a transmission and a propulsion shaft (not shown).

On the other hand, the rotational power is transmitted to the generator 14 via the power transmission mechanism 20. Then, the electric power generated by the generator 14 is charged in the battery 15 or supplied to the electric auxiliary machine 16. Examples of the electric auxiliary machine 16 include an apparatus that is driven by power supply such as a headlamp, a vehicle interior lamp, a brake lamp, an audio device, and an electronically controlled fuel injection valve 12.

  The power transmission mechanism 20 includes a driving pulley 21 fixed to the crankshaft 13, a driven pulley 22 fixed to the drive shaft 17 of the generator 14, and an endless shape wound around the driving pulley 21 and the driven pulley 22. Belt 23.

  In the power transmission mechanism 20, the rotational power of the crankshaft 13 is generated by a reference rotation ratio R1 / R2 determined by the diameter R1 (pitch circle diameter) of the driving pulley 21 and the diameter R2 (pitch circle diameter) of the driven pulley 22. Decelerating or accelerating. The belt 23 is exemplified by a V belt.

  In such an engine 10, a crank angle sensor 31 as a rotational speed detection device, an accelerator opening sensor 35 as an opening detection device, a voltage regulator 36 that varies the voltage of the generator 14, and signals between them. And a control device 30 for inputting and outputting. Then, when the control device 30 audits the operating state of the engine 10 based on the engine speed Ne and the accelerator pedal opening Ap, and determines that the operating state is in the slip increase region A1, the power generation of the generator 14 Control is performed to reduce the amount Pm.

  The control device 30 includes a CPU that performs various processes, a program used to perform the various processes, a processing result, an internal storage device that can read and write map data M3, which will be described later, and various interfaces. In addition to the above sensors, the control device 30 is connected to a current sensor 32 that detects the current value Im of the generator 14 as an output detection device, and a warning light 33 that is arranged on the meter panel 19 as a warning device. The As a program of the control device 30, there are a program for controlling the fuel injection amount of the fuel injection valve 12 according to the detection value of the accelerator opening sensor 35 and a program for reducing the power generation amount Pm that is an output value of the generator 14. Illustrated.

  The crank angle sensor 31 is a sensor that detects an engine rotational speed Ne that is the rotational speed of the crankshaft 13, and an electromagnetic pickup sensor that rotates a disk provided with a protrusion in the circumferential direction and detects the protrusion by an electromagnetic pickup. Is exemplified.

  The accelerator opening sensor 35 is a sensor that detects an accelerator opening Ap that indicates the amount of depression of the accelerator pedal 18, and is exemplified by a contactless magnetic sensor.

  The voltage regulator 36 is a device that holds the voltage Vm output from the generator 14 at a substantially constant reference voltage V0 (for example, 12V) without being influenced by the engine speed Ne. That is, in other words, the voltage regulator 36 is a device that can vary the voltage Vm output from the generator 14 with respect to the current value Im that is proportional to the rotational speed of the drive shaft 17.

  Hereinafter, a control method of the engine 10 will be described as a function of the control device 30 with reference to the flowchart of FIG. This control method starts after the engine 10 is started, and ends when the engine 10 is stopped.

  First, in step S <b> 10, the control device 30 acquires the engine speed Ne via the crank angle sensor 31. Next, in step S <b> 20, the control device 30 acquires an accelerator opening Ap indicating the depression amount of the accelerator pedal 18 via the accelerator opening sensor 35.

  Next, in step S30, the control device 30 determines whether or not the operating state of the engine 10 based on the acquired engine speed Ne and the accelerator opening Ap is within the range of the slip increase region A1. In step S30, a performance characteristic curve L1 of the engine 10 based on the engine speed Ne and the accelerator opening Ap (or the fuel injection amount and output torque corresponding to the accelerator opening Ap) is set in advance through experiments and tests. The calculated map data M3 is used for calculation.

  FIG. 3 shows map data M3 that is a performance characteristic diagram of the engine 10 based on the engine speed Ne and the accelerator pedal opening Ap. The hatched area in the figure indicates the slip increase area A1.

  The slip increase region A1 is a region where the slip of the belt 23 is predicted to occur and increase in advance. In other words, this slip increase area A1 is measured in advance in experiments and tests to determine whether or not slip occurs and increases due to the rotational fluctuation of the engine 10 and the load applied to the belt 23, and is shown in the performance characteristic diagram of the engine 10 shown in FIG. This is the area to be set. Note that the slip in the slip increase region A1 excludes a belt 23 that constantly occurs in a state where the belt 23 is deteriorated due to a decrease in tension or wear.

  Moreover, this slip increase area | region A1 is comprised from the low rotation area | region A2 and the high opening degree area | region A3. The low rotation region A2 is a partial region on the low rotation side where the engine speed Ne is low in this performance characteristic diagram, and more specifically, a region existing along the performance characteristic curve L1 on the low rotation side. It is. The high opening region A3 is a partial region on the high opening side of the accelerator opening Ap in the performance characteristic diagram, and more specifically, along the performance characteristic curve L1 on the high opening side. It is an existing area.

  Therefore, when the operating state of the engine 10 is in the range of the slip increase region A1, the operating state of the engine 10 is in the range of the low rotation region A2 and the rotation fluctuation is large, or the high This indicates that the belt 23 is in one of the states where the belt 23 is in an opening range A3 and an excessive load is applied to the belt 23.

  If it is determined in step S30 that the operating state of the engine 10 is in the slip increase region A1, that is, if it is predicted that slip of the belt 23 will occur and increase, the process proceeds to step S40. On the other hand, when it determines with it not being in slip increase area | region A1, it returns to a start.

  Next, in step S <b> 40, the control device 30 decreases the voltage Vm by the voltage regulator 36 and decreases the power generation amount Pm output from the generator 14. Note that the control in step S40 does not temporarily reduce the power generation amount Pm output from the generator 14, but if the operating state of the engine 10 is in the slip increase region A1 in step S30, the reduced state. Will continue to be maintained. That is, the amount of power generation from when it is determined in step S30 that the operating state of the engine 10 is in the slip increase region A1, until it is determined again in step S30 that the operating state of the engine 10 is not in the slip increase region A1. It keeps the decrease in Pm.

  The power generation amount Pm of the generator 14 is a value obtained by multiplying the output current value Im and the voltage Vm. In order to reduce the power generation amount Pm without changing the engine speed Ne, that is, without changing the current value Im, the voltage Vm is reduced. As described above, the voltage regulator 36 adjusts the voltage Vm output from the generator 14 to a substantially constant reference voltage V0. Therefore, in step S40, the voltage regulator 36 adjusts the voltage Vm to a voltage lower than the reference voltage V0.

  Thus, by reducing the voltage Vm, the power generation amount Pm of the generator 14 can be reduced, and the load on the generator 14 is reduced as the power generation amount Pm decreases. As a result, in the low-rotation region A2 where the rotational fluctuation of the engine 10 is large, the load on the generator 14 is reduced, so that the generator 14 can follow the rotational fluctuation, and the slip of the belt 23 is suppressed. The On the other hand, in the high opening degree region A3 where an excessive load is applied to the belt 23, an excessive load applied to the belt 23 is reduced by reducing the load of the generator 14, so that the slip of the belt 23 is suppressed.

  In this step S40, it is desirable that the control device 30 calculates the decrease Pb of the power generation amount Pm based on the output value Pe of the engine 10, the power generation amount Pm, and the slip rate Rs. Step S40 will be described as a function of the control device 30 with reference to FIG.

  First, in step S41, the control device 30 calculates the rotational speed Np of the driven pulley 22 according to the power generation amount Pm. In this step S41, calculation is performed using map data M2 created by acquiring the rotational speed Np based on the power generation amount Pm in advance through experiments and tests.

  FIG. 5 shows map data M2 in which the rotational speed Np of the driven pulley 22 based on the power generation amount Pm is set. As shown in this map data M2, the rotational speed Np of the driven pulley 22 has a positive correlation with the power generation amount Pm.

  Next, in step S43, the control device 30 calculates the slip ratio Rs of the belt 23 based on the engine speed Ne and the calculated rotation speed Np of the driven pulley 22. The slip ratio Rs is a value obtained by dividing the difference between the reference rotation ratio R1 / R2 and the actual rotation ratio Ne / Np by the reference rotation ratio R1 / R2. In other words, the engine rotational speed Ne is the rotational speed of the driving pulley 21. That is, the ratio between the engine speed Ne and the speed Np of the driven pulley 22 is the actual actual speed ratio Ne / Np. The slip ratio Rs can be calculated by directly detecting the speed of the belt 23. However, since a dedicated non-contact sensor for detecting the speed is required, the slip ratio Rs The ratio is preferably used.

  Next, in step S45, the control device 30 calculates the output value Pe of the engine 10. The output value Pe is a value obtained by multiplying the engine speed Ne by the output torque Te obtained from the accelerator opening Ap.

  Next, in step S47, the control device 30 calculates a decrease Pb of the power generation amount Pm of the generator 14 based on the output value Pe of the engine 10, the power generation amount Pm, and the slip rate Rs. In this step S41, the reduction value Pb based on the output value Pe, the power generation amount Pm, and the slip rate Rs of the engine 10 is obtained in advance through experiments and tests, and calculated using map data M4 created.

  FIG. 6 illustrates the map data M4 in which the decrease value Pb based on the output value Pe, the power generation amount Pm, and the slip rate Rs of the engine 10 is set. The map data M4 is 3D map data having three parameters, but here, the correlation between each parameter and the decrease Pb is individually illustrated. As shown in this map data M4, the decrease Pb has a positive correlation with each parameter.

  Next, in step S49, the control device 30 decreases the voltage Vm by the voltage regulator 36 based on the calculated decrease Pb, and decreases the power generation amount Pm output from the generator 14.

  Next, as shown in FIG. 2, in step S50, the control device 30 determines whether or not the slip ratio Rs exceeds the slip threshold Rb. The slip threshold Rb is set in advance by experiments and tests, is set to a positive value, and is set to a value that can determine that the belt 23 has deteriorated due to a decrease in tension or wear. In this step S50, it is only necessary to be able to determine that the deterioration of the belt 23 has progressed, and the step of comparing the slip rate in the previous control method with the current slip rate Rs, or the difference between them and the threshold value are determined. You may make it the step to compare. However, the slip threshold value Rb is preferably set to an upper limit value when the belt 23 is further deteriorated and the slip is constantly generated over the entire operation range of the engine 10.

  If it is determined in step S50 that the slip ratio Rs exceeds the slip threshold Rb, that is, if it is determined that the deterioration of the belt 23 has progressed, the process proceeds to step S60. On the other hand, when it is determined that the slip ratio Rs is equal to or less than the slip threshold Rb, the process returns to the start.

  Next, in step S60, the control device 30 expands the slip increase region A1. More specifically, the low rotation region A2 is expanded to the higher rotation side, the high opening region A3 is expanded to the lower opening side, and the entire region of the slip increase region A1 is expanded.

  FIG. 7 exemplifies the slip increase area A1 enlarged by this step S60. It should be noted that the enlargement ratio of the slip increase area A1 is preferably increased in accordance with the slip ratio Rs, that is, as the slip ratio Rs increases. When step S60 is completed, the process returns to the start.

  By performing the control in steps S10 to S40 as described above, the power generation amount Pm of the generator 14 is reduced in advance before the slip of the belt 23 occurs and increases according to the operating state of the engine 10. Thus, the load on the generator 14 is reduced. As a result, in the low-rotation region A2 where the rotational fluctuation of the engine 10 is large, the load on the generator 14 decreases, so that the generator 14 can follow the rotational fluctuation. Increase is avoided. Similarly, even in the high opening region A3 where an excessive load is applied to the belt 23, an excessive load applied to the belt 23 is reduced by reducing the load of the generator 14, so that the occurrence and increase of the slip of the belt 23 occur. Is avoided. In general, when the operating state of the engine 10 is in the slip increase region A1, the occurrence and increase of the slip of the belt 23 is avoided.

  That is, by avoiding the occurrence of abnormal noise and wear due to the slip of the belt 23 in advance, a response delay until the load on the generator 14 actually decreases is avoided. Deterioration can be reliably suppressed.

  Further, since the decrease in the power generation amount Pm of the generator 14 is determined in the operating state of the engine 10, the belt 23 can be controlled by simpler control compared to the conventional technique that detects the sudden increase of the crank angular velocity or the slip of the belt 23. The occurrence and increase of slip can be avoided.

  In addition, in the slip increase region A1, the generator 14 can be reliably driven by the rotational power transmitted from the crankshaft 13 without the belt 23 slipping, so that compared with the case where the belt 23 slips, The amount Pm can be brought close to the target value. That is, it is possible to avoid the deterioration of fuel consumption and the malfunction of the electric auxiliary machine 16 due to the decrease in the power generation amount Pm of the generator 14 due to the slip of the belt 23.

  Further, in step S40, the decrease Pb of the power generation amount Pm of the generator 14 is calculated from the output value Pe of the engine 10, the power generation amount Pm, and the slip rate Rs, so that the excessive power generation amount Pm is decreased. The occurrence and increase of the slip of the belt 23 can be avoided.

  In addition, in steps S50 and S60, the slip increase area A1 is expanded in accordance with the progress of deterioration of the belt 23 such as a decrease in tension and wear, so that even if the deterioration of the belt 23 progresses, the slip of the belt 23 increases. Generation and increase can be surely prevented.

  In step S50, the slip threshold value Rb is sequentially increased to set the slip increase region A1 corresponding to the progressive deterioration of the belt 23. Therefore, the occurrence and increase of the slip of the belt 23 can be set. It becomes advantageous for suppression.

  Moreover, it is preferable to set the slip threshold Ra as the upper limit of the slip threshold Rb. The slip threshold Ra is set in advance through experiments and tests, and is set to a value that can be used to determine that the belt 23 has deteriorated and that slip has occurred constantly throughout the operating range of the engine 10. Is done. In other words, the slip threshold Ra is set to a value that can determine a state where the belt 23 needs to be serviced.

  As described above, when it is determined that the slip ratio Rs exceeds the slip threshold Ra, that is, when it is determined that the belt 23 needs to be inspected and maintained, the warning lamp 33 is used to warn the driver. This warning prompts the driver to inspect and maintain the belt 23, thereby preventing the malfunction at an early stage.

  When the auxiliary machine is a water pump, if it is of a variable capacity type (for example, a swash plate type), the capacity is varied, or the flow rate of the cooling water flowing in is adjusted and discharged from the water pump. It is preferable to reduce the cooling water discharge flow rate.

  Similarly, when the auxiliary machine is an air compressor, if it is of a variable displacement type (for example, a swash plate type), the capacity is varied, or the flow rate of the inflowing gas is adjusted and discharged from the air compressor. The discharge flow rate of compressed gas may be reduced.

  Similarly, when the auxiliary machine is a hydraulic pump, if it is of a variable displacement type (for example, a swash plate type), its capacity is varied, or the flow rate of the inflowing oil is adjusted and discharged from the hydraulic pump. The oil discharge flow rate should be reduced.

  When the auxiliary machine is a coupling fan, the rotational speed and the air volume may be reduced by a fan clutch made of a viscous or fluid coupling.

10 Engine 13 Crankshaft 14 Generator (auxiliary machine)
17 Drive shaft 20 Power transmission mechanism 21 Driving pulley 22 Driven pulley 23 Belt 30 Control device 31 Crank angle sensor (rotational speed detection device)
35 Accelerator opening sensor (opening detector)
Ap Accelerator opening degree Ne Engine speed A1 Slip increase region Pm Power generation amount (output value)

Claims (7)

A driving pulley fixed to the crankshaft, a driven pulley fixed to a drive shaft of an auxiliary machine whose output value is adjustable, and an endless belt wound around the driving pulley and the driven pulley; In an engine equipped with a power transmission mechanism
A rotational speed detection device that detects an engine rotational speed that is the rotational speed of the crankshaft;
An opening detection device for detecting the accelerator opening of the accelerator pedal;
These rotational speed detection devices, opening detection devices, and a control device that inputs and outputs signals between the auxiliary machine,
The control device audits the operating state of the engine based on the engine speed and the accelerator opening, and determines that the operating state is in a slip increasing region where the belt slip is predicted to occur and increase in advance. In such a case, the engine is configured to perform control to reduce the output value of the auxiliary machine.   2. The engine according to claim 1, wherein the slip increase region exists along a performance characteristic curve on a low rotation side where the engine speed is low in a performance characteristic diagram based on the engine speed and the accelerator opening.   The said slip increase area | region exists along the performance characteristic curve by the side of the high opening degree where the said accelerator opening degree is high in the performance characteristic figure based on the said engine speed and the said accelerator opening degree. engine. An output detection device for detecting the output value of the auxiliary machine,
The control device includes a reference rotation ratio based on the diameter of the driving pulley and the diameter of the driven pulley, and an actual rotation ratio of the rotation speed of the driven pulley calculated according to the engine speed and the output value. Calculate the slip ratio of the belt based on
The engine according to any one of claims 1 to 3, wherein the engine is configured to perform control to expand the slip increase region in accordance with the calculated slip ratio.   The engine according to claim 4, wherein the control device is configured to calculate a decrease in the output value of the auxiliary machine based on the operating state of the engine, the output value, and the slip ratio.   The engine according to any one of claims 1 to 5, wherein the auxiliary machine includes any one, some combination, or all of a generator, a water pump, an air compressor, a coupling fan, and a hydraulic pump. Rotational power is transmitted from the driving pulley fixed to the crankshaft to the driven pulley fixed to the drive shaft of the auxiliary machine that can adjust the output value via an endless belt, and the auxiliary machine is In a control method of a driving engine,
Obtaining an operating state of the engine;
Determining whether or not the acquired operating state of the engine is in a slip increasing region where the slip of the belt is predicted to occur and increase in advance;
And a step of decreasing the output value of the auxiliary machine when it is determined that the operating state of the engine is in the slip increase region.