JP2015151838A - Construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction machine capable of reducing fluctuation in workability of a hydraulic actuator even when a different type of fuel is supplied to a diesel engine.SOLUTION: A hybrid hydraulic shovel 1 comprises: a diesel engine 6 which drives a hydraulic pump 8; and an assist power generation motor 7 which assists the diesel engine 6. The assist power generation motor 7 is supplied with electric power from a power storage device 16 through an electric power conversion device 17. A controller 22 controls performance of the electric power conversion device 17. When non-diesel fuel is selected through a fuel selection device 24, the controller 22; compares an actual rotation speed N and actual torque T of the diesel engine 6 with a rotation speed N0 and torque T0 indicated by an engine control dial 23; and supplies the assist power generation motor 7 with electric power to compensate a divergence value ΔT.

Description

  The present invention relates to a construction machine such as a hydraulic excavator equipped with, for example, a diesel engine.

  In general, construction machines such as a hydraulic excavator that drives a hydraulic pump by a diesel engine are known (see, for example, Patent Document 1). In such a construction machine, a diesel engine is driven by light oil, and pressure oil from a hydraulic pump is supplied to a hydraulic actuator such as a hydraulic cylinder or a hydraulic motor to perform excavation work or the like by a work device.

JP 2010-37855 A

  By the way, in recent years, in order to mitigate the progress of global warming, reduction of carbon dioxide emissions is desired. The main cause of carbon dioxide emissions into the atmosphere is a large consumption of fossil fuels such as light oil. Therefore, there is an increasing need for non-fossil fuels that do not rely on fossil fuels. However, since non-fossil fuels have fuel properties different from those of fossil fuels, there are cases where there are considerations in use.

  For example, as a non-fossil fuel as an alternative fuel for light oil, biodiesel fuel mainly composed of fatty acid methyl ester has emerged, but the heat quantity of this fuel is about 10% lower than that of light oil. Therefore, when biodiesel fuel is burned by a diesel engine, the work of the engine is reduced compared to light oil.

  When a diesel engine burns fuel that has a lower calorific value than light oil, the work of the engine is reduced, and the flow rate and pressure of the pressure oil supplied from the hydraulic pump are reduced, causing a decrease in workability by the hydraulic actuator. there is a possibility. In addition, in order to generate a predetermined amount of heat, a larger amount of fuel than light oil is required, and fuel consumption is deteriorated. Not only that, the diesel engine is tuned for light oil combustion, so for other fuels with different fuel properties, the diesel engine cannot be controlled to the output desired by the operator and the fuel injection amount is excessive. There is also a possibility that it becomes unstable due to repeated shortage and shortage.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is a construction machine that can reduce fluctuations in workability due to a hydraulic actuator even when different types of fuel are supplied to a diesel engine. Is to provide.

  In order to solve the above-mentioned problems, the invention of claim 1 is directed to a diesel engine supplied with a plurality of types of fuels having different calorific values, a hydraulic pump driven by the diesel engine, and an assist generator motor driven to rotate by the diesel engine. And a power storage device electrically connected to the assist power generation motor, and a controller for controlling the assist power generation motor, further comprising a fuel selection device that selects a type of fuel to be supplied to the diesel engine The controller controls electric power supplied from the power storage device to the assist power generation motor according to the type of fuel selected by the fuel selection device, and when a low heat amount fuel is selected, a high heat amount The output torque of the diesel engine that is insufficient compared to the fuel of the It is characterized in that compensate by the generator motor.

  In the invention of claim 2, the diesel engine is driven by non-light oil fuel other than light oil including light oil or biodiesel fuel, and the controller selects light oil when the non-light oil fuel is selected by the fuel selection device. Compared to the case, the electric power supplied to the assist generator motor is increased.

  According to a third aspect of the present invention, the diesel engine is rotationally driven at a rotational speed designated by an engine control dial, and a rotational speed sensor that measures the actual rotational speed of the diesel engine, and a load that measures the load of the diesel engine. And when the non-light oil fuel is selected by the fuel selection device, the controller selects the non-light oil fuel from the power storage device according to the rotational speed measured by the rotational speed sensor and the load measured by the load sensor. The power supplied to the assist generator motor is adjusted.

  According to a fourth aspect of the present invention, the controller is a deviation value between the rotational speed and load of the diesel engine designated by the engine control dial and the actual rotational speed and load measured by the rotational speed sensor and the load sensor. Power supplied from the power storage device to the assist power generation motor is adjusted.

  In the invention of claim 5, when the remaining amount of electricity stored in the power storage device falls below a predetermined value, the controller is configured until the remaining amount of electricity reaches the predetermined value even when non-light oil fuel is selected. Power is supplied from the assist power generation motor to the power storage device, and power is supplied again to the assist power generation motor after the remaining power storage reaches the predetermined value.

  According to the first aspect of the present invention, when a plurality of types of fuel having different amounts of heat are supplied to the diesel engine, the output torque of the diesel engine changes according to the type of fuel. At this time, the controller controls the power supplied from the power storage device to the assist power generation motor in accordance with the type of fuel selected by the fuel selection device. For this reason, when the low heat quantity fuel is selected, the output torque of the diesel engine that is insufficient compared to the high heat quantity fuel can be compensated by the assist power generation motor. As a result, even when a plurality of types of fuel having different heat amounts are supplied to the diesel engine, the hydraulic pump can be driven with substantially the same output torque as when, for example, a fuel having a high amount of heat is used, regardless of the type of fuel. As a result, regardless of the type of fuel, hydraulic actuators such as hydraulic cylinders and hydraulic motors connected to the hydraulic pump can be driven with substantially constant operability.

  According to the invention of claim 2, when the non-light oil fuel is selected by the fuel selection device, the electric power supplied to the assist power generation motor is increased compared to when the light oil is selected. Thereby, even when the amount of heat of the non-light oil fuel is lower than that of light oil and the output torque of the diesel engine is insufficient, the rotation torque of the assist power generation motor can be increased to compensate for the shortage of the output torque. For this reason, the output torque of the engine that varies depending on the type of fuel can be smoothed based on the output torque of light oil.

  According to the invention of claim 3, in order to smooth the output torque of the engine, the diesel engine measures the actual rotational speed and the load in addition to the recognition of the rotational speed and the load indicated by the engine control dial. Rotation speed sensor and load sensor. For this reason, the electric energy supplied from an assist electric power generation motor can be adjusted according to the measurement result of these sensors.

  According to the fourth aspect of the present invention, the speed and load of the diesel engine instructed by the engine control dial are compared with the actual speed and load of the diesel engine, so that the deviation value is compensated from the power storage device. The power is supplied to the assist generator motor. For this reason, even when a non-light oil fuel having a calorific value different from that of light oil is supplied to the diesel engine, the output torque of the engine is not insufficient, and work performance according to the specifications of the construction machine can be ensured.

  According to the fifth aspect of the present invention, even when the non-light oil fuel is selected, if the remaining amount of power stored in the power storage device falls below a predetermined value, the assist power generation motor automatically charges the power storage device to the predetermined value. For this reason, since the power storage device is controlled so that a remaining amount equal to or greater than a predetermined value is always secured, it is possible to suppress a reduction in the life of the power storage device due to overdischarge that occurs when the remaining power amount is small.

1 is a front view showing a hybrid hydraulic excavator according to an embodiment of the present invention. FIG. 2 is a block diagram showing a hydraulic system and an electric system applied to the hybrid excavator in FIG. 1. It is a block diagram which shows the specific example of the fuel selection apparatus in FIG. It is a characteristic diagram which shows the relationship between the rotation speed and torque of a diesel engine when light oil and non-light oil fuel are used.

  Hereinafter, a hybrid hydraulic excavator will be described as an example of a construction machine according to an embodiment of the present invention with reference to the accompanying drawings.

  1 to 3 show an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a hybrid hydraulic excavator (hereinafter referred to as a hydraulic excavator 1) that uses a diesel engine 6 and an assist generator motor 7 in combination. The hydraulic excavator 1 includes a self-propelled crawler-type lower traveling body 2, a turning device 3 provided on the lower traveling body 2 and driven to turn by a turning motor 12 described later, and a turning device 3 on the lower traveling body 2. The upper turning body 4 is mounted so as to be able to turn through the work, and the working device 5 is provided on the front side of the upper turning body 4 and performs excavation work or the like.

  Further, the work device 5 includes, for example, a boom 5A, an arm 5B, and a bucket 5C, and a boom cylinder 5D, an arm cylinder 5E, and a bucket cylinder 5F as hydraulic actuators for driving them. The boom 5A, the arm 5B, and the bucket 5C are pin-coupled to each other and move up and down by extending or contracting the cylinders 5D to 5F.

  Reference numeral 6 denotes a diesel engine mounted on the upper swing body 4, and an assist power generation motor 7 and a hydraulic pump 8 are connected to the diesel engine 6. Further, the diesel engine 6 is connected to a fuel tank 9, and a plurality of types of fuels having different heat amounts are supplied from the fuel tank 9. Specifically, the diesel engine 6 is supplied with light oil or non-light oil fuel from the fuel tank 9, and is driven by these fuels. At this time, the non-light oil fuel is a fuel other than light oil including, for example, biodiesel fuel.

  The diesel engine 6 is provided with a rotation speed sensor 10 for measuring the rotation speed N of the output shaft and a torque sensor 11 as a load sensor for measuring the rotation torque (output torque T) of the diesel engine 6. ing. The torque sensor 11 may directly measure the output torque T of the diesel engine 6 or may indirectly measure the output torque T of the hydraulic pump 8 based on the discharge pressure or the discharge flow rate of the hydraulic pump 8.

  In addition, the assist power generation motor 7 is rotationally driven by the diesel engine 6 during power generation to supply generated power to a power storage device 16 described later. On the other hand, the assist power generation motor 7 assists the diesel engine 6 by being rotationally driven by power supply from the power storage device 16 during assist driving. Further, the hydraulic pump 8 is driven by the diesel engine 6 and discharges pressure oil toward the cylinders 5D to 5F of the work device 5.

  Reference numeral 12 denotes a turning motor for driving the turning device 3, and the turning motor 12 is constituted by, for example, an electric motor 13 and a hydraulic motor 14 as a hydraulic actuator. Here, the rotating shafts of the electric motor 13 and the hydraulic motor 14 are connected to each other. The turning motor 12 drives the turning device 3 via a speed reduction mechanism (not shown). When the upper swing body 4 is driven to turn, the electric motor 13 is driven to rotate by power supply from the power storage device 16 and assists the turning drive by the hydraulic motor 14. On the other hand, when the turning of the upper swing body 4 is stopped, the electric motor 13 performs a regenerative operation and outputs regenerative power to the power storage device 16. Thereby, the power storage device 16 is charged. For example, the swing motor 12 may be configured by using only the electric motor 13 without the hydraulic motor 14.

  The hydraulic motor 14 of the turning motor 12 and the cylinders 5D to 5F of the work device 5 are connected to the hydraulic pump 8 via the control valve 15. The control valve 15 is formed by a plurality of hydraulic control valves that control the swing motor 12 and the work device 5. The control valve 15 switches the supply and discharge of the pressure oil supplied from the hydraulic pump 8 in accordance with the operation of an operation means such as an operation lever, an operation pedal, etc. (both not shown). Thereby, the control valve 15 controls the turning operation of the upper turning body 4 and the up-and-down movement of the work device 5.

  Reference numeral 16 denotes a power storage device provided in the upper swing body 4, and this power storage device 16 is constituted by, for example, an electric double layer capacitor. The power storage device 16 stores electric charges supplied from the assist power generation motor 7 during power generation, and supplies drive power toward the assist power generation motor 7 during assist driving. The power storage device 16 stores the electric charge supplied from the electric motor 13 during the regenerative operation, and supplies drive power toward the electric motor 13 during the turning assist drive. The power storage device 16 may be constituted by a rechargeable battery such as a lithium ion battery.

  Reference numeral 17 denotes a power conversion device provided between the power storage device 16 and the assist power generation motor 7. The power conversion device 17 includes inverters 18 and 19 that can convert DC power and AC power to each other, and a chopper 20 that boosts or lowers the DC voltage. Operation is controlled. The inverter 18 is connected to the assist power generation motor 7, the inverter 19 is connected to the electric motor 13 of the turning motor 12, and the chopper 20 is connected to the power storage device 16. Inverters 18 and 19 and chopper 20 are connected to each other via DC buses 21A and 21B. When the power storage device 16 is configured by a rechargeable battery (secondary battery), the chopper 20 may be omitted and the power storage device 16 may be directly connected to the DC buses 21A and 21B.

  During power generation by the assist power generation motor 7, the power conversion device 17 converts the three-phase AC power supplied from the assist power generation motor 7 into DC power, and steps down the DC power and supplies the DC power to the power storage device 16. 16 is charged. On the other hand, when the assist power generation motor 7 is driven (at the time of assist drive), the power conversion device 17 boosts the DC power supplied from the power storage device 16 and then converts it into three-phase AC power to convert the assist power generation motor 7. To supply.

  Further, during regeneration of the electric motor 13, the power conversion device 17 converts the regenerative power generated by the electric motor 13 into DC power, and steps down the DC power and supplies it to the power storage device 16 to charge the power storage device 16. On the other hand, at the time of turning assist driving by the electric motor 13, the power conversion device 17 converts the DC power from the power storage device 16 into AC driving power and supplies it to the electric motor 13.

  Reference numeral 22 denotes a controller for controlling the power conversion device 17, and the controller 22 is constituted by, for example, a microcomputer. Here, the rotation speed sensor 10 and the torque sensor 11 are connected to the controller 22. In addition to this, the controller 22 is connected to an engine control dial 23 for instructing a desired rotational speed N0 and torque T0 for the diesel engine 6 and a fuel selection for selecting the type of fuel supplied to the diesel engine 6. A device 24 is connected. The controller 22 is also connected to the power storage device 16 and monitors the remaining amount of power storage, and controls the power conversion device 17 according to the remaining amount.

  The engine control dial 23 indicates the rotational speed N0 and the torque T0 based on the relationship between the rotational speed N and the torque T when light oil is used, for example, as shown by the characteristic line 26 in FIG. At this time, the engine control dial 23 switches the instructed rotational speed N0 and torque T0 between two values, a high value and a low value, according to, for example, a heavy load and a light load. The engine control dial 23 may switch the rotation speed N0 and the torque T0 with three or more values or may switch with a continuous value. If the relationship between the rotational speed N0 and the torque T0 is clear in advance, the engine control dial 23 may indicate only the rotational speed N0.

  The fuel selection device 24 includes a plurality of (for example, two) buttons 24A and 24B that can be selected in accordance with, for example, the type of fuel. Specifically, when the button 24A is pressed, the light oil is selected, and when the button 24B is pressed, the non-light oil fuel is selected. FIG. 3 illustrates the case where the fuel selection device 24 includes two buttons 24A and 24B. For example, when a plurality of types of non-light oil fuels having different concentrations of biodiesel fuel are used, the fuel is selected. The selection device 24 may increase the number of buttons according to the types of these fuels. In addition, when only two types of light oil and non-light oil fuel are used, the fuel selection device 24 includes a single button, and whether or not the fuel is non-light oil fuel is determined by whether or not this button is pressed. Good.

  The controller 22 then selects the actual rotational speed N and output torque T measured by the rotational speed sensor 10 and the torque sensor 11, the instruction signal from the engine control dial 23, and the selection from the fuel selection device 24, as will be described later. Based on the signal, the assist drive of the assist generator motor 7 is controlled.

  Next, a specific control operation by the controller 22 will be described for the assist drive of the assist power generation motor 7 according to the type of fuel.

  First, when a predetermined rotational speed N0 and torque T0 are instructed from the engine control dial 23 to the diesel engine 6 by the operator, an amount of fuel (for example, light oil) necessary to satisfy these instruction values is supplied to the fuel tank 9. To be supplied to the diesel engine 6. At this time, the diesel engine 6 is driven according to the amount of light oil supplied, and the hydraulic pump 8 is driven to rotate according to the output torque T of the diesel engine 6 to discharge the pressure oil. Thus, the pressure oil is supplied to the cylinders 5D to 5F and the hydraulic motor 14 which are hydraulic actuators, and the working device 5 moves up and down, and the upper swing body 4 is driven to rotate.

  Here, the rotational speed N0 and the torque T0 instructed by the engine control dial 23 are set on the assumption that light oil is used as the fuel for the diesel engine 6. Specifically, the instructed rotational speed N0 and torque T0 follow, for example, the characteristic line 26 in FIG. 4 based on the relationship between the rotational speed N and the torque T of the diesel engine 6 when light oil is used. Value is set. Therefore, when light oil is used, the rotational speed N0 and torque T0 instructed by the engine control dial 23 are adjusted by adjusting the amount of light oil supplied to the diesel engine 6 based on the actual rotational speed N or the like. Thus, the diesel engine 6 can be driven.

  On the other hand, non-light oil fuel containing biodiesel fuel has a lower calorific value than light oil. For this reason, when non-light oil fuel is used for the fuel of the diesel engine 6, the output torque T of the diesel engine 6 is lower than when light oil is used. Therefore, when non-light oil fuel is used, the actual rotational speed N and torque T are based on the relationship between the rotational speed N and torque T of the diesel engine 6 when non-light oil fuel is used. The rotational speed N1 and the torque T1 according to the characteristic line 27 of FIG. As a result, when non-light oil fuel is used, the difference value ΔN, between the rotational speed N0 and torque T0 instructed by the engine control dial 23 and the actually measured rotational speed N1 and torque T1. ΔT is generated.

  At this time, the hydraulic excavator 1 according to the present embodiment includes the fuel selection device 24, and the fuel supplied to the diesel engine 6 is made to correspond to whether the fuel is light oil or non-light oil fuel including biodiesel fuel. This can be determined by pressing the buttons 24A and 24B. As shown in FIG. 3, when the operator selects the non-light oil fuel by the fuel selection device 24, that is, when the operator presses the button 24B corresponding to the non-light oil fuel, the controller 22 performs the following control operation.

  First, the lamp 25 is lit to inform the operator that the present invention is applied. Subsequently, the controller 22 measures the actual rotational speed N and torque T of the diesel engine 6, and compares these measured values with the rotational speed N0 and torque T0 instructed by the engine control dial 23. When non-light oil fuel is used, the actual rotational speed N and torque T become the rotational speed N1 and torque T1 according to the characteristic line 27 in FIG. The rotation speed N1 and torque T1 thus followed are compared with the rotation speed N0 and torque T0 according to the characteristic line 26 in FIG.

  As a result of the comparison, when a deviation is recognized between each of the rotational speeds N0 and N1 and the torques T0 and T1, the controller 22 calculates the amount of electric power necessary to compensate for the deviation value ΔT of the torque T, for example. The controller 22 controls the power conversion device 17 based on the calculated power amount, and supplies power according to the calculated power amount from the power storage device 16 toward the assist power generation motor 7.

  The assist generator motor 7 generates an output torque corresponding to the supplied power and assists the driving of the hydraulic pump 8 by the diesel engine 6. As a result, the engine output corresponding to the deviation can be supplemented, and the hydraulic pump 8 can be driven with the torque T0 when using light oil even when non-light oil fuel having a heat quantity different from that of light oil is burned. As a result, even if a non-light oil fuel having a heat quantity different from that of light oil is supplied to the diesel engine 6, it is possible to ensure work performance according to specifications preset in the hydraulic excavator 1.

  In addition, although the controller 22 gave and demonstrated the structure which supplies the electric power which supplements deviation value (DELTA) T of the torque T to the assist electric power generation motor 7 as an example, this invention is not limited to this. For example, the controller 22 may supply electric power to the assist power generation motor 7 so that the deviation value ΔN of the rotational speed N becomes smaller in addition to the deviation value ΔT of the torque T. That is, the controller 22 supplies the assist power generation motor 7 so that the characteristics of the rotation speed N and the torque T approach the characteristic line 26 in FIG. 4 when using light oil even when non-light oil fuel is used. What is necessary is just to control the electric power to perform.

  Thus, according to the present embodiment, the controller 22 controls the electric power supplied from the power storage device 16 to the assist power generation motor 7 according to the type of fuel selected by the fuel selection device 24. Specifically, when non-light oil fuel is selected by the fuel selection device 24, the electric power supplied to the assist power generation motor 7 is increased compared to when light oil is selected.

  For this reason, when the low heat quantity non-light oil fuel is selected, the output torque T of the diesel engine 6 which is insufficient compared to the high heat quantity light oil can be compensated by the assist power generation motor 7. As a result, the output torque T of the diesel engine 6 that varies depending on the type of fuel can be brought close to the output torque T0 when using light oil. As a result, even when a plurality of types of fuel with different calorific values are supplied to the diesel engine 6, the hydraulic pump 8 can be driven with substantially the same output torque T0 as when using light oil, regardless of the type of fuel, and the cylinders 5D to 5D. 5F, the hydraulic actuator such as the hydraulic motor 14 can be driven with substantially constant operability.

  Further, in order to smooth the output torque T of the diesel engine 6, that is, to approach the output torque T 0 when using light oil, the diesel engine 6 has the rotational speed N 0 and the torque T 0 (load) indicated by the engine control dial 23. In addition to recognition, a rotation speed sensor 10 and a torque sensor 11 for measuring the actual rotation speed N and torque T are provided. In addition to this, the controller 22 compares the rotational speed N0 and the torque T0 instructed by the engine control dial 23 with the actual rotational speed N and the torque T by the diesel engine 6, and stores the electric power so as to compensate for the deviation value ΔT, for example. Electric power is supplied from the device 16 to the assist generator motor 7.

  For this reason, for example, even when a non-light oil fuel having a different concentration of biodiesel fuel and a different amount of heat is used every time fuel is supplied, the assist generator motor 7 is used in accordance with the measurement results of these sensors 10 and 11. The amount of power supplied from can be adjusted. As a result, even when a plurality of types of non-light oil fuels having a calorific value different from that of diesel oil are used as the fuel for the diesel engine 6, the output torque T of the diesel engine 6 is not short, and the specifications of the hydraulic excavator 1 are met. Work performance can be ensured.

  Furthermore, the controller 22 monitors the remaining amount of power stored in the power storage device 16, and if the remaining amount falls below a predetermined value, the remaining amount of stored electricity reaches the predetermined value even when non-light oil fuel is selected. The power is supplied to the power storage device 16 from the assist power generation motor 7 until the power storage device 16 is charged, and the power is supplied to the assist power generation motor 7 again after the remaining power storage reaches a predetermined value. Accordingly, since the power storage device 16 is controlled so as to always ensure a remaining amount equal to or greater than a predetermined value, it is possible to suppress a reduction in the life of the power storage device 16 due to overdischarge that occurs when the remaining power storage amount is small. At the time of charging, the lamp 25 may be switched from a normal lighting state to a blinking state in order to notify that the assist power generation motor 7 does not perform an assist operation even when non-light oil fuel is selected. In this case, when the remaining amount of power stored in the power storage device 16 reaches a predetermined value, the controller 22 supplies power to the assist power generation motor 7 again to perform an assist operation, and the lamp 25 is switched from a blinking state to a lighting state.

  In the embodiment, the controller 22 is configured to adjust the power supplied to the assist power generation motor 7 based on the rotation speed N and the torque T measured by the rotation speed sensor 10 and the torque sensor 11. However, the present invention is not limited to this. For example, when the characteristics of the rotational speed and torque when the non-light oil fuel is used are known in advance, the insufficient torque corresponding to the rotational speed can be understood only by selecting the fuel. Therefore, electric power corresponding to this insufficient torque may be supplied to the assist power generation motor 7. In this case, the torque sensor can be omitted.

  In the above embodiment, the fuel selection device 24 selects the type of fuel by the operator manually operating the buttons 24A and 24B. However, the present invention is not limited to this. For example, the fuel selection device may be configured by a fuel discrimination sensor provided in the fuel tank 9. In this case, the fuel discrimination sensor automatically discriminates the type of fuel filled in the fuel tank 9 and outputs a selection signal corresponding to the type of fuel to the controller 22.

  In the above embodiment, the crawler type hybrid hydraulic excavator 1 is described as an example of the construction machine. However, the present invention may be applied to a wheel type hybrid hydraulic excavator or a hybrid wheel loader. The present invention can be applied to various construction machines including an assist generator motor that assists driving.

DESCRIPTION OF SYMBOLS 1 Hybrid type hydraulic excavator 2 Lower traveling body 3 Turning device 4 Upper turning body 5 Working device 6 Diesel engine 7 Assist power generation motor 8 Hydraulic pump 10 Rotational speed sensor 11 Torque sensor 12 Turning motor 13 Electric motor 14 Hydraulic motor 16 Power storage device 17 Electric power Conversion device 22 Controller 23 Engine control dial 24 Fuel selection device 24A, 24B Button

Claims (5)

A diesel engine that is supplied with multiple types of fuel with different calories;
A hydraulic pump driven by the diesel engine;
An assist generator motor that is rotationally driven by the diesel engine;
A power storage device electrically connected to the assist generator motor;
In a construction machine comprising a controller for controlling the assist generator motor,
A fuel selection device for selecting a type of fuel to be supplied to the diesel engine;
The controller controls the power supplied from the power storage device to the assist power generation motor according to the type of fuel selected by the fuel selection device,
A construction machine characterized in that, when a low heat quantity fuel is selected, the output torque of the diesel engine, which is insufficient compared to a high heat quantity fuel, is compensated by the assist power generation motor. The diesel engine is driven by non-light oil fuel other than light oil including light oil or biodiesel fuel,
2. The construction machine according to claim 1, wherein when the non-light oil fuel is selected by the fuel selection device, the controller increases the power supplied to the assist power generation motor as compared to when the light oil is selected. The diesel engine is driven to rotate at a rotational speed designated by an engine control dial,
A rotation speed sensor for measuring an actual rotation speed of the diesel engine; and a load sensor for measuring a load of the diesel engine,
When the non-light oil fuel is selected by the fuel selection device, the controller supplies the assist power generation motor from the power storage device according to the rotational speed measured by the rotational speed sensor and the load measured by the load sensor. The construction machine according to claim 2, wherein the electric power is adjusted.   The controller is configured to compensate for a deviation value between a rotational speed and a load instructed by the engine control dial of the diesel engine and an actual rotational speed and the load measured by the rotational speed sensor and the load sensor. The construction machine according to claim 3, wherein electric power supplied from an apparatus to the assist generator motor is adjusted.   When the remaining amount of power stored in the power storage device falls below a predetermined value, the controller causes the power storage device from the assist power generation motor to reach the predetermined value even when non-light oil fuel is selected. The construction machine according to claim 3, wherein electric power is supplied to the auxiliary power generation motor and the electric power is supplied again to the assist power generation motor after the remaining power amount reaches the predetermined value.

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