Fuel property detection method in engine drive type work machine and arrangement structure for fuel property detection sensor

Abstract

To early determine wrong fuel supply when a different type of fuel from fuel that has been already supplied is wrongly supplied into the fuel tank of an engine drive type work machine.SOLUTION: A sampling chamber 14 with a small volume is provided in the fuel tank 10 of an engine drive type work machine, and in the sampling chamber 14, part of fuel that has already been supplied into the fuel tank 10 is sampled. At start of fuel supply into the fuel tank 10, fuel of which supply has been started is introduced into the sampling chamber 14 and is mixed with the relatively small amount of sampled fuel, and a change of properties of the fuel in the sampling chamber is detected by a sensor 30 and monitored. Due to this, when wrong fuel supply occurs, even if wrongly supplied fuel is a relatively small amount, the fuel properties in the sampling chamber 14 are largely changed, so as to enable early determination of the wrong fuel supply.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fuel characteristics detection method for an engine-driven working machine, and a fuel characteristics detection sensor arrangement structure for executing the fuel characteristics detection method, and more specifically, to a fuel characteristics detection method suitable for monitoring changes in fuel characteristics that occur when an engine-driven working machine is erroneously refueled with a fuel type different from the fuel already being refueled, and a fuel characteristics detection sensor arrangement structure capable of implementing the fuel characteristics detection method. [Background technology]

[0002] As society becomes more concerned about environmental issues, the demand for decarbonization is also growing in the civil engineering and construction industries, and there is a demand to reduce carbon dioxide emissions from engine-driven work machines such as engine-driven generators and engine-driven compressors, which are often used in the civil engineering and construction industries.

[0003] In response to these demands, there is a social demand for the fuel used in engine-driven work machinery to be switched from diesel to alternative fuels that emit less carbon dioxide than diesel, such as B5 diesel, which is diesel with 5% or less biodiesel fuel added, B100 fuel, which is 100% biodiesel fuel, and GTL fuel, which is fuel refined from natural gas.

[0004] On the other hand, B100 fuel and GTL fuel are expensive and can be difficult to obtain in some areas, so there are still many situations in which diesel has to be used.As a result, it is not always the case that the same type of fuel is used for a single engine-driven work machine. Rather, any one type of fuel selected from diesel or diesel alternative fuels may be used for refueling, taking into consideration various factors such as economic efficiency, the difficulty of obtaining biofuels and other fuels at the site where the engine-driven work machine is installed, and the owner's requests.

[0005] Here, under the Local Tax Act, B5 diesel, which is treated as diesel or light oil, is subject to diesel transaction tax, but B100 fuel and GTL fuel are not subject to taxation.

[0006] On the other hand, mixed fuels produced by mixing diesel or B5 diesel with B100 fuel or GTL fuel are also subject to diesel transaction tax if they fall under the category of "diesel" under the Local Tax Act.

[0007] Therefore, for example, if B100 fuel or GTL fuel is mistakenly filled with diesel or B5 diesel remaining in the fuel tank, or if diesel or B5 diesel is mistakenly filled with B100 fuel or GTL fuel remaining in the fuel tank, causing these fuels to mix in the fuel tank and produce a mixed fuel that corresponds to "diesel" under the Local Tax Act, the "consumption" of the mixed fuel produced in this way is subject to the diesel transaction tax stipulated in the Local Tax Act (Article 144-3, item 5 of the Local Tax Act), and therefore the "consumption" of the aforementioned mixed fuel that is carried out without paying the diesel transaction tax is illegal.

[0008] Therefore, when refueling an engine-driven work machine that has been fueled with diesel or B5 diesel with B100 fuel or GTL fuel, or when refueling an engine-driven work machine that has been fueled with B100 fuel or GTL fuel with diesel or B5 diesel, it is necessary to drain all of the fuel already in the engine-driven work machine before filling it with new fuel.

[0009] In addition to diesel alternative fuels such as B100 fuel and GTL fuel, there are also cases where fuel tanks of engine-driven work machines that are filled with diesel are mistakenly or intentionally filled with fuels such as kerosene, which are not subject to diesel transaction tax, and the use of the mixed fuel produced in this way also constitutes tax evasion of the diesel transaction tax mentioned above and is illegal.

[0010] In addition to the local tax law issues mentioned above, there is also the possibility of accidentally filling engine-driven work machinery equipped with diesel engines with gasoline.

[0011] For these reasons, if a fuel of a different type from the fuel already being fueled into an engine-driven work machine is mistakenly filled with fuel and mixed in the fuel tank to produce a mixed fuel, the mixed fuel that is produced must be disposed of without being used. Furthermore, depending on the type of fuel that was mistakenly filled, extremely complicated post-processing will be required, such as maintenance work such as disassembling and cleaning the fuel injection pump and fuel injection nozzle installed in the engine.

[0012] Therefore, in the event of erroneous refueling in which a type of fuel different from that in use is supplied to an engine-driven work machine, it is desirable to determine the occurrence of such erroneous refueling and immediately stop the refueling operation by issuing a warning to the refueling worker, and, in some cases, take measures such as making it impossible to start the engine or bringing the engine to an emergency stop.

[0013] Here, since the characteristics of fuel differ depending on the type of oil, if fuel of a different type is mistakenly added to the fuel already present in the fuel tank and mixed with it, the characteristics of the fuel in the fuel tank will change to approach the characteristics of the mis-added fuel as the amount of mis-added fuel increases.

[0014] Therefore, whether or not the above-mentioned mis-fueling has occurred in an engine-driven work machine can be determined by placing a sensor that detects the characteristics of the fuel (referred to in this application as a "fuel characteristics detection sensor") in the fuel supply system of the engine-driven work machine and monitoring changes in the fuel characteristics detected by this fuel characteristics detection sensor.As an example, it can be determined that mis-fueling has occurred if the fuel characteristics detected by the fuel characteristics detection sensor change beyond a predetermined threshold value.

[0015] When detecting such fuel characteristics as the ultrasonic propagation speed, capacitance, thermal conductivity, etc., the sensors used to detect these characteristics are those that use sensors with the detection part submerged in the fuel (hereinafter, such sensors will be referred to as "liquid-submerged type"), and if the detection part of the sensor is exposed above the fuel liquid surface, the fuel characteristics cannot be detected.

[0016] On the other hand, since refueling of engine-driven work machines is usually performed when the amount of fuel remaining in the fuel tank becomes low, if a submerged fuel characteristics detection sensor is used to determine whether erroneous refueling has occurred, it is necessary to position the fuel characteristics detection sensor so that its detection section remains submerged in the fuel even when the amount of fuel remaining in the fuel tank becomes low. Therefore, as an example of the positioning of such a fuel characteristics detection sensor, it is advantageous to adopt a configuration in which detection section 130a of fuel characteristics detection sensor 130 is positioned near the bottom of fuel tank 110, as shown in Figure 7.

[0017] Although not related to the placement of a sensor for monitoring changes in fuel characteristics due to incorrect refueling, Patent Document 1 listed below proposes a configuration for the placement of a sensor 230 for detecting the ingress of seawater into a fuel tank 210 of a ship sailing at sea, in which a detection portion 230a of the sensor 230 is placed in a recess 210c provided in the bottom of the fuel tank 210 as shown in Figure 8. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] JP 2022-170644 A Summary of the Invention [Problem to be solved by the invention]

[0019] In the arrangement structure of the fuel characteristic detection sensor 130 illustrated in FIG. 7, the detection portion 130a of the sensor 130 is arranged near the bottom of the fuel tank 110, so that as long as there is approximately 1 / 4 of the upper limit FLmax of the fuel remaining in the fuel tank 110 (dashed line "1 / 4FL" in FIG. 7), the detection portion 130a of the fuel characteristic detection sensor 130 can be submerged in the fuel.

[0020] However, since the fuel in the fuel tank 110 is sucked in through the intake port 122 of the fuel supply pipe 121 and supplied to the engine, the fuel level drops to a lower limit position FLmin determined by the opening position of the intake port 122 of the fuel supply pipe 121 at a minimum.

[0021] Therefore, if this lower limit position FLmin is located lower than the detection section 130a of the fuel characteristic detection sensor 130, when the fuel is consumed up to the lower limit position FLmin, the detection section 130a of the fuel characteristic detection sensor 130 will be exposed above the fuel liquid surface and will not be able to detect the characteristics.

[0022] From this point of view, when attempting to monitor changes in fuel characteristics resulting from improper refueling based on the detection signal of fuel characteristics detection sensor 130 in the configuration shown in Figure 7, it is necessary to start refueling when detection section 130a of fuel characteristics detection sensor 130 is submerged in fuel (when approximately 1 / 4 of the fuel tank capacity remains).

[0023] Here, although there are identifiable differences in the characteristics of diesel and diesel alternative fuels (e.g., B5 diesel, B100 fuel, GTL fuel, etc.) that can be used in diesel engines that are commonly installed in engine-driven work machines, these characteristics are relatively similar, so the mixing of a small amount of another type of fuel into one of the fuels does not result in a significant change in the characteristics that exceeds the threshold required to determine whether mis-fueling has occurred, and the occurrence of mis-fueling cannot be determined until the mis-fueled fuel is mixed in a high ratio with the fuel stored in the fuel tank 110.

[0024] As a result, the more fuel remaining in the fuel tank 110, the more a large amount of fuel must be dispensed before it is possible to determine that a fuel mis-filling has occurred. When a fuel mis-filling is determined to have occurred, a large amount of mixed fuel will be produced that must be disposed of, and it will take a long time from the start of the fuel mis-filling until it is determined that a fuel mis-filling has occurred.

[0025] In this way, if it takes a long time for a determination to be made that a fuel error has occurred, there is a possibility that the mis-fueled fuel will be introduced into the engine before the determination is made, for example, if the mis-fueling occurs while the engine is running.

[0026] In contrast, the sensor arrangement structure described in the above-mentioned Patent Document 1 adopts a configuration in which a recess 210c is provided at the bottom of the fuel tank 210 and the detection unit 230a of the sensor 230 is arranged within this recess 210c. Therefore, if this sensor 230 arrangement structure is adopted for the fuel tank of an engine-driven work machine and the lower limit position FLmin of the fuel in the fuel tank 210 is set to a position higher than the recess 210c as shown in Figure 8, then even if the fuel in the fuel tank 210 is consumed down to the lower limit position FLmin, the detection unit 230a of the sensor 230 can be maintained submerged in the fuel accumulated in the recess 210c.

[0027] As a result, when the capacity of the recess 210c is made sufficiently small, it becomes possible for the sensor 230 to operate normally even when refueling is started with a small amount of fuel remaining in the fuel tank 210, as compared to the configuration described with reference to Figure 7.

[0028] However, in Patent Document 1, by providing a recess 210c at the bottom of the fuel tank 210, seawater, which has a higher specific gravity than fuel, is preferentially introduced into the recess 210c, making it possible to detect the presence of seawater early even when the amount of seawater mixed in is relatively small.However, diesel and B5 diesel have similar specific gravities to B100 fuel and GTL fuel, and even if one of these is mixed with the other, the two will mix without separating. Therefore, the early detection of the presence of small amounts of different fluids by utilizing the difference in specific gravity, which is a feature of Patent Document 1, is not useful in determining whether mis-fueling has occurred.

[0029] Therefore, even if a configuration is adopted in which a recess 210c is provided at the bottom of the fuel tank of an engine-driven work machine as shown in Figure 8, mis-fueling cannot be determined until the mis-fueled fuel is mixed in a high ratio with the total fuel remaining in the fuel tank 210.Therefore, even if there is an improvement in comparison with the configuration shown in Figure 7, a large amount of mixed fuel is still produced when mis-fueling occurs, and it takes a relatively long time from the start of mis-fueling until the mis-fueling is determined.Furthermore, if mis-fueling occurs while the engine is running, the mis-fueled fuel may be supplied to the engine before the mis-fueling is determined.

[0030] Therefore, the present invention has been made to eliminate the drawbacks of the above-mentioned conventional technology, and aims to provide a fuel characteristics detection method for engine-driven working machines and an arrangement structure of a fuel characteristics detection sensor that, in the event of erroneous refueling in which a different type of fuel than the fuel already contained in the fuel tank is refueled, can extract and detect changes in the fuel characteristics required to determine the occurrence of erroneous refueling, such as a significant change in characteristics that exceeds a predetermined threshold, at the time when a relatively small amount of fuel is erroneously refueled, and therefore early after the occurrence of the erroneous refueling. [Means for solving the problem]

[0031] The means for solving the problems are described below together with the reference numerals used in the description of the embodiment of the invention. These reference numerals are described in order to clarify the correspondence between the description of the claims and the description of the embodiment of the invention, and needless to say, are not used to restrict the interpretation of the technical scope of the present invention.

[0032] In order to achieve the above object, the fuel characteristic detection method for an engine-driven working machine of the present invention includes the steps of: In an engine-driven working machine having an engine (not shown) and a fuel tank 10 for supplying fuel to the engine through a fuel supply pipe 21, The fuel tank 10, A fuel storage chamber 13 in which the suction port 22 of the fuel supply pipe 21 is open, A sampling chamber 14 formed as a small-capacity space is provided with respect to the fuel storage chamber 13, A part of the fuel already supplied to the fuel tank 10 is sampled in the sampling chamber 14 by leaving it therein up to a residual height HL, which is a predetermined height above the opening position (Fmin) of the suction port 22 of the fuel supply pipe 21 (see FIG. 2(B)). When refueling of the fuel tank 10 is started, the fuel that has started to be refueled in the fuel tank 10 is introduced into the sampling chamber 14 and mixed with the fuel sampled in the sampling chamber 14, and then the fuel that has overflowed from the sampling chamber 14 is introduced into the fuel storage chamber 13 (see FIG. 2(C)). It is characterized in that a predetermined characteristic of the fuel is detected in the sampling chamber 14 (claim 1).

[0033] The detection portion 30a of the submerged fuel characteristic detection sensor 30 is accommodated in the sampling chamber 14 at a position lower than the residual height HL, The fuel characteristic detection sensor 30 can detect the characteristics of the fuel in the sampling chamber 14 (claim 2).

[0034] The residual height HL may be set to the same height as the upper limit height HH of the fuel that can be stored in the sampling chamber 14 (claim 3; see FIG. 1).

[0035] In addition, the residual height HL is set to a predetermined lower height than the upper limit height HH of the fuel that can be stored in the sampling chamber 14, When fuel is not being refueled into the fuel tank 10, the sampling is performed by leaving fuel at the residual height HL in the sampling chamber 14, It is also possible to configure the fuel storage height in the sampling chamber 14 to be raised to the upper limit height HH when fuel supply to the fuel tank 10 begins, and to store the fuel that has begun to be supplied to the fuel tank 10 in the sampling chamber 14 until it reaches the upper limit height HH (Claim 4; see Figure 3 and the modified examples in Figures 5 and 6).

[0036] In addition, the arrangement structure of the fuel characteristic detection sensor in the engine-driven working machine of the present invention is as follows: In an engine-driven working machine having an engine (not shown) and a fuel tank 10 for supplying fuel to the engine through a fuel supply pipe 21, The fuel tank 10, A fuel storage chamber 13 in which the suction port 22 of the fuel supply pipe 21 is open, A sampling chamber 14 formed as a small-capacity space is provided with respect to the fuel storage chamber 13, The sampling chamber 14 is formed as a bottomed container-like space provided below a fuel filler port 16 provided in the fuel tank 10 and at a position where the fuel filled through the fuel filler port 16 flows down, and is configured so that a portion of the fuel already filled in the fuel tank 10 is sampled by remaining therein up to a residual height HL, which is a predetermined height equal to or higher than the opening position (Fmin) of the suction port 22 of the fuel supply pipe 21; The sampling chamber 14 and the fuel storage chamber 13 are communicated with each other so that the fuel introduced into the sampling chamber 14 through the fuel filler port 16 can be overflowed from the sampling chamber 14 and introduced into the fuel storage chamber 13, A detection portion 30a of a fuel characteristic detection sensor 30 for detecting a predetermined characteristic of the fuel is accommodated in the sampling chamber 14 (claim 5).

[0037] When the fuel characteristic detection sensor 30 is a submerged sensor, It is desirable to accommodate the detection portion 30a of the fuel property detection sensor 30 within the sampling chamber 14 at a position lower than the residual height HL (claim 6).

[0038] The residual height HL can be set to the same height as the upper limit height HH of the fuel that can be stored in the sampling chamber 14 (claim 7; see FIG. 1).

[0039] Also, the residual height HL is set to a predetermined lower height than the upper limit height HH of the fuel that can be stored in the sampling chamber 14, It is also possible to provide a variable storage height mechanism 40 which allows fuel to remain at the residual height HL in the sampling chamber 14 when the fuel tank 10 is not being refueled, and which raises the storage height of fuel in the sampling chamber 14 to the upper limit height HH when refueling of the fuel tank 10 begins (Claim 8; see the modified examples in Figures 3 and 5 and 6).

[0040] Both the sampling chamber 14 and the fuel storage chamber 13 can be provided within a single fuel tank 10, and the sampling chamber 14 can be provided on the bottom side within the fuel tank 10 (claim 9; see Figures 1 to 4).

[0041] In this case, a guide plate 17 for guiding the fuel supplied through the fuel supply port 16 toward the sampling chamber 14 may be provided inside the fuel tank 10 (claim 10; see FIG. 4).

[0042] In a configuration in which both the sampling chamber 14 and the fuel storage chamber 13 are provided within a single fuel tank 10, the sampling chamber 14 may be provided at the upper side within the fuel tank 10 (claim 11; see Figure 5).

[0043] Furthermore, the fuel tank 10 is formed by combining a main tank 11 which serves as the fuel storage chamber 13 and a sub-tank 12 which serves as the sampling chamber 14, The sub-tank 12 is provided with the fuel supply port 16, It is also possible to adopt a configuration in which an outlet 12a provided at the upper end of the side wall of the sub-tank 12 and an inlet 11a provided at the upper end of the side wall of the main tank 11 are connected to each other (claim 12; see FIG. 6). Effect of the Invention

[0044] With the configuration of the present invention described above, the present invention can provide the following significant effects.

[0045] A sampling chamber 14 is provided in the fuel tank 10 of an engine-driven work machine, which is formed as a small-capacity space compared to the fuel storage chamber 13, and a portion of the fuel already supplied to the fuel tank 10 is sampled in this sampling chamber 14 while remaining there in the sampling chamber 14 up to a predetermined residual height HL.When refueling of the fuel tank 10 begins, the fuel supplied to the fuel tank 10 is introduced directly into the sampling chamber 14 and mixed with the fuel sampled in the sampling chamber 14, and fuel overflowing from the sampling chamber 14 is introduced into the fuel storage chamber 13.In this manner, in the event of erroneous refueling in which a type of fuel different from the fuel stored in the fuel tank 10 is supplied, the fuel from which refueling has begun mixes with the relatively small amount of fuel sampled in the sampling chamber 14, and the characteristics of the fuel in the sampling chamber 14 will show a significant change even if only a relatively small amount of fuel was erroneously supplied.

[0046] As a result, by placing a fuel property detection sensor 30 in the sampling chamber 14 and monitoring changes in the properties of the fuel in the sampling chamber 14, it is possible to detect changes in the fuel properties (e.g., changes in properties exceeding a predetermined threshold value) required to determine whether or not refueling has occurred in an extremely short time after refueling has begun.By making it possible to determine whether or not refueling has occurred at an early stage, the refueling worker can be made to stop refueling at an early stage and the amount of mixed fuel that must be disposed of, etc., can be reduced.

[0047] When the fuel characteristics detection sensor 30 is of a submerged type, in a configuration in which the detection section 30a of the fuel characteristics detection sensor 30 is accommodated at a position lower than the residual height HL in the sampling chamber 14, the detection section 30a of the fuel characteristics detection sensor 30 can be kept submerged in the fuel at all times, and the fuel characteristics detection sensor 30 can operate normally to detect changes in the fuel characteristics regardless of the fuel consumption status in the fuel storage chamber 13.

[0048] In a configuration in which the aforementioned residual height HL, which is the height of the fuel remaining in the sampling chamber 14, and the upper limit height HH of the fuel that can be stored in the sampling chamber 14 are the same height, the arrangement structure of the fuel characteristic detection sensor can be simplified.

[0049] On the other hand, in a configuration in which the residual height HL is set to a predetermined lower height than the upper limit height HH, fuel of the residual height HL is left in the sampling chamber 14 when refueling is not being performed, and a variable storage height mechanism 40 is provided which raises the fuel storage height in the sampling chamber 14 to the upper limit height HH when refueling of the fuel tank 10 begins, the storage height in the sampling chamber 14 rises during refueling, so that even in the event of erroneous refueling, the erroneously-refueled fuel can be stored in the sampling chamber 14 until it reaches the upper limit height HH, and by determining that erroneous refueling has occurred during this time and taking measures such as stopping the refueling operation, the erroneously-refueled fuel can be prevented from exceeding the sampling chamber 14 and being introduced into the fuel storage chamber 13.

[0050] As a result, even if incorrect refueling occurs, the fuel stored in the fuel storage chamber 13 can be used as is without being discarded, etc., so only the fuel in the sampling chamber 14 needs to be discarded, making it possible to significantly reduce the amount of fuel that needs to be discarded, etc.

[0051] Furthermore, by being able to prevent mis-fueled fuel from flowing into the fuel storage chamber 13, even if mis-fueling occurs while the engine is operating, the mis-fueled fuel will not be introduced into the engine.

[0052] In a configuration in which the sampling chamber 14 and the fuel storage chamber 13 are provided within a single fuel tank 10, and the sampling chamber 14 is provided on the bottom side of the fuel tank 10, by providing an induction plate 17 within the fuel tank 10 that guides fuel supplied through a fuel filler port 16 into the sampling chamber 14, it is possible to reliably guide fuel to the sampling chamber 14.

[0053] In addition, in a configuration in which the sampling chamber 14 is provided on the bottom side of the fuel tank 10, if refueling is performed when there is a large amount of fuel remaining in the fuel storage chamber 13, the sampling chamber 14 will be submerged in the fuel stored in the fuel storage chamber 13, and the fuel added through the fuel fill port 16 cannot be directly introduced into the sampling chamber 14, making it impossible to determine whether mis-fueling has occurred until a large amount of the mis-fueled fuel has mixed with the entire fuel in the fuel tank 10.

[0054] In contrast to this, even if a configuration is adopted in which the sampling chamber 14 and the fuel storage chamber 13 are similarly provided within a single fuel tank 10, if a configuration is adopted in which the sampling chamber 14 is provided on the upper side of the fuel tank 10, even if a large amount of fuel remains in the fuel tank 10, the fuel supplied through the fuel filler port 16 can be introduced directly into the sampling chamber 14, and as a result, it becomes possible to quickly determine whether or not there has been erroneous fuel supply regardless of the amount of fuel remaining in the fuel storage chamber.

[0055] Furthermore, in a configuration in which the sampling chamber 14 is provided at the upper side of the fuel tank 10, the fuel introduced through the fuel filler port 16 can be reliably introduced into the sampling chamber 14 without the need for an induction plate 17 as is used in a configuration in which the sampling chamber 14 is provided at the bottom side of the fuel tank 10.

[0056] Furthermore, in a configuration in which the fuel tank 10 is formed by combining a main tank 11 which constitutes the fuel storage chamber 13 and a sub-tank 12 which constitutes the sampling chamber 14, the sub-tank 12 is provided with the fuel fill port 16, and the outlet 12a provided at the upper end of the side wall of the sub-tank 12 is connected to the inlet 11a provided at the upper end of the side wall of the main tank 11, the fuel tank provided in an existing engine-driven working machine is made into the above-mentioned main tank 11, a sub-tank 12 is added to it, and a sampling chamber 14 is provided, the arrangement structure of the fuel characteristic detection sensor of the present invention can be relatively easily adopted by retrofitting the sub-tank 12 without significantly changing the basic structure of the existing engine-driven working machine. [Brief description of the drawings]

[0057] [Figure 1] 1 is an explanatory diagram of a layout structure of a fuel characteristic detection sensor in an engine-driven working machine according to an embodiment of the present invention; [Diagram 2] FIG. 2 is an explanatory diagram of changes in state within the fuel tank in the configuration example of FIG. 1, in which (A) is a state in which a nearly full amount of fuel is stored, (B) is a state in which the fuel has been consumed up to the lower limit position FLmin, and (C) is a state in which refueling (mis-fueling) has begun from the state of (B). [Diagram 3] FIG. 11 is an explanatory diagram showing an arrangement structure of a fuel characteristic detection sensor in an engine-driven working machine according to another embodiment of the present invention. [Figure 4] 4A and 4B are explanatory diagrams showing examples of modifications in which a guide plate is added to the configurations of FIGS. 1 and 3, where (A) is an example of a modification to the configuration of FIG. 1, and (B) is an example of a modification to the configuration shown in FIG. 3. [Diagram 5] 5A and 5B are explanatory diagrams showing the arrangement structure of a fuel characteristic detection sensor in an engine-driven working machine according to another embodiment of the present invention, where (A) is a front view and (B) is a side view. [Figure 6] FIG. 11 is an explanatory diagram showing an arrangement structure of a fuel characteristic detection sensor in an engine-driven working machine according to another embodiment of the present invention. [Figure 7] An assumed diagram of a configuration in which the sensor is placed directly on the bottom side inside the fuel tank. [Figure 8] FIG. 1 is an explanatory diagram of a sensor arrangement structure in Patent Document 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] The layout structure of the fuel property detection sensor in the engine-driven working machine of the present invention will be described below with reference to the attached drawings.

[0059] [Target engine-driven working machines] The arrangement structure of the fuel characteristics detection sensor of the present invention is not limited to any particular engine-driven working machine that has an engine (not shown) and a fuel tank 10 that supplies fuel to the engine via a fuel supply pipe 21, and can be applied to a variety of such machines. As an example, such engine-driven working machines include an engine-driven generator having a generator main body, an engine-driven compressor having a compressor main body, and an engine-driven pump having a pump, as the working machine main body (not shown) driven by the engine, and the arrangement structure of the fuel characteristics detection sensor of the present invention can be adopted for any of these engine-driven working machines.

[0060] In the following embodiments, the explanation will be given assuming that the engine installed in the engine-driven working machine is a diesel engine, but this is not limited to this example, and the configuration of the present invention may also be adopted for engine-driven working machines equipped with a gasoline engine.

[0061] [Fuel property detection sensor arrangement] FIG. 1 shows the layout structure of a fuel property detection sensor for an engine-driven working machine according to one embodiment of the present invention.

[0062] The reference numeral 10 in FIG. 1 denotes a fuel tank which supplies fuel to an engine (not shown) via a fuel supply pipe 21. Within this fuel tank 10 there is provided a fuel storage chamber 13 into which an intake port 22 of the fuel supply pipe 21 opens, and a sampling chamber 14 which is formed as a small-capacity space relative to the fuel storage chamber 13.

[0063] In the embodiment of Figure 1, the fuel supply pipe 21 is inserted downward from the upper side of the fuel storage chamber 13, with the lower end of the fuel supply pipe 21 serving as the suction port 22; however, the arrangement of the fuel supply pipe 21 is not limited to this configuration, and it is also possible to adopt a configuration in which the upper end of the fuel supply pipe 21 inserted upward from the bottom side of the fuel storage chamber 13 serves as the suction port 22, or a configuration in which the end of the fuel supply pipe 21 inserted horizontally from the side wall of the fuel tank 10 serves as the suction port 22, and various other known configurations are possible.

[0064] In the embodiment shown in Figure 1, the aforementioned fuel storage chamber 13 is formed throughout the single fuel tank 10, and the aforementioned sampling chamber 14 is formed within the fuel storage chamber 13 by dividing the fuel storage chamber 13 with a partition wall 15.

[0065] In the embodiment shown in FIG. 1, a partition wall 15 is erected on the bottom wall 10a of the fuel tank 10, and a sampling chamber 14 is formed between the side wall 10b of the fuel tank 10 and the partition wall 15, with the bottom wall 10a of the fuel tank 10 as its bottom surface. The sampling chamber 14 is formed as a bottomed box-shaped space below a fuel filler port 16 provided on the fuel tank 10 and opening upward toward the fuel filler port 16.

[0066] Since the sampling chamber 14 is thus formed as a space that opens upward into the fuel storage chamber 13, in the embodiment of Figure 1, fuel can be stored in the sampling chamber 14 up to an upper limit height HH determined by the upper end position of the partition wall 15, and the fuel storage chamber 13 and the sampling chamber 14 are connected (continuous) at this upper limit height HH (the portion indicated by the dashed line HH in Figure 1).

[0067] Therefore, when the fuel liquid level FL in the fuel storage chamber 13 is at a height below the aforementioned upper limit height HH (the upper end position of the partition wall 15) and fuel exceeding the upper limit height HH (the upper end position of the partition wall 15) is introduced into the sampling chamber 14, the fuel exceeding the upper limit height HH will overflow over the partition wall 15 and into the fuel storage chamber 13 (see Figure 2 (C)).

[0068] On the other hand, even if the fuel liquid level FL in the fuel storage chamber 13 exceeds the upper limit height HH of the sampling chamber 14 (the upper end position of the partition wall 15) and the sampling chamber 14 is submerged in the fuel stored in the fuel storage chamber 13 (see Figure 2 (A)), and the fuel in the fuel storage chamber 13 is consumed and the liquid level FL drops to a height below the upper limit height HH of the sampling chamber 14, the sampling chamber 14 is configured so that fuel can remain in the sampling chamber 14 up to the upper end position of the partition wall 15 (residual height HL).

[0069] Therefore, in the embodiment shown in Figure 1, the upper limit height HH, which is the upper limit position of the fuel that can be stored in the sampling chamber 14, is the residual height HL, which is the height of the fuel that remains in the sampling chamber 14 and is sampled, and both heights (HH, HL) are the same height.

[0070] In the illustrated example, the upper end position of the partition wall 15 is set to the aforementioned residual height HL and upper limit height HH, but it is also possible to adopt a configuration in which the aforementioned residual height HL and upper limit height HH are lowered to the lower end position of the notch or opening relative to the upper end of the partition wall 15 by providing a notch in the upper edge of the partition wall 15 or by providing an opening near the upper end of the partition wall 15.

[0071] As described above, the height of the upper end of the partition wall 15 that defines the sampling chamber 14 is set to be higher than the opening position of the suction port 22 of the fuel supply pipe 21, i.e., the lower limit position FLmin of the fuel liquid level FL in the fuel storage chamber 13. Therefore, even if the fuel in the fuel storage chamber 13 is consumed and the fuel liquid level is consumed to the lower limit position FLmin (the opening position of the suction port of the fuel supply pipe 21), fuel remains in the sampling chamber 14 up to the upper end position (residual height HL) of the partition wall 15 (see Figure 2 (B)). Therefore, by accommodating the detection portion 30a of the fuel characteristic detection sensor 30 in the sampling chamber 14 at a position lower than the upper end position (residual height HL) of the partition wall 15, the detection portion 30a of the fuel characteristic detection sensor 30 can be kept always submerged in fuel.

[0072] The fuel characteristics detected by this fuel characteristic detection sensor 30 are not limited to any particular characteristics as long as they can be used to distinguish between different types of fuel, and it is possible to detect a variety of characteristics.Furthermore, it is also possible to detect not just one characteristic, but a combination of multiple characteristics, in which case the detection sections of the sensors, the number of which corresponds to the characteristics to be combined, may be provided within the sampling chamber 14.

[0073] Examples of such fuel characteristics include the ultrasonic propagation speed, capacitance, thermal conductivity, etc. of the fuel, and the sensors that detect these characteristics (ultrasonic sensors, capacitance sensors, thermal conductivity sensors) are all submerged sensors that are used with the detection section 30a submerged in the fuel to be detected. However, as mentioned above, by storing the detection section 30a of the fuel characteristic detection sensor 30 at a position lower than the residual height HL in the sampling chamber 14, the fuel characteristics can always be detected even if a submerged type fuel characteristic detection sensor 30 is used.

[0074] In addition, reference numeral 33 in FIG. 1 denotes a drain outlet for discharging the fuel in the fuel storage chamber 13 to the outside of the fuel tank 10, and reference numeral 34 denotes a drain outlet for discharging the fuel in the sampling chamber 14 to the outside of the fuel tank 10.

[0075] Furthermore, the symbol 24 in Figure 1 denotes a return pipe for returning fuel that is not injected by a fuel injection pump provided on the engine (not shown) of the engine-driven work machine, which is a diesel engine in this embodiment, to the fuel tank 10. For example, if the engine mounted on the engine-driven work machine is a gasoline engine, there is no need to provide the return pipe 24.

[0076] In an engine-driven working machine equipped with the fuel characteristic detection sensor arrangement structure of the present invention configured as described above, when the fuel tank 10 is filled with fuel (see Figure 2(A)), and the fuel is consumed and the fuel in the fuel storage chamber 13 decreases, the fuel liquid level FL in the fuel storage chamber 13 reaches the upper end position (HL = HH) of the partition wall 15 of the sampling chamber 14, and then, as fuel consumption continues, it drops to a minimum lower limit position FLmin determined by the opening position of the suction port 22 of the fuel supply pipe 21 (see Figure 2(B)).

[0077] In this way, even if the fuel in the fuel storage chamber 13 is consumed down to the lower limit position FLmin, the sampling chamber 14 is configured to retain a storage amount of fuel up to the upper end position (HL = HH) of the partition wall 15 so that it can be sampled, and therefore the detection section 30a of the fuel characteristic detection sensor 30 can always be kept submerged in fuel.

[0078] In this way, when fuel supply is started through the fuel filler port 16 when the fuel liquid level FL in the fuel storage chamber 13 has fallen below the upper end position (HL=HH) of the partition wall 15, or in the illustrated embodiment, has fallen to the lower limit position FLmin, the fuel introduced into the fuel tank 10 through the fuel filler port 16 at the start of refueling is directly introduced into the sampling chamber 14, which is formed as a bottomed box-shaped space that opens upward toward the fuel filler port 16 below the fuel filler port 16, and after mixing with the fuel sampled in the sampling chamber 14, the fuel that overflows from the sampling chamber 14 flows over the partition wall 15 into the fuel storage chamber 13 (see Figure 2(C)).

[0079] If a fuel mis-filling occurs, in which a different type of fuel than the fuel stored in the fuel tank 10 is filled, the mis-filled fuel will mix with the relatively small amount of fuel sampled in the sampling chamber 14, and even just a relatively small amount of mis-filling will result in a significant change in the characteristics of the fuel in the sampling chamber 14.

[0080] Therefore, by detecting the characteristics of the fuel in the sampling chamber 14 and monitoring the changes, it is possible to determine that mis-fueling has occurred relatively quickly after it begins, and this determination result can be used to stop the mis-fueling at an early stage, and in cases where refueling is carried out while the engine is running, measures can be taken such as stopping the engine before the mis-fueled fuel reaches the engine.

[0081] In the embodiment described above with reference to Figures 1 and 2, a configuration has been described in which both the storage height (residual height HL) of the fuel remaining in the sampling chamber 14 and the upper limit height HH, which is the maximum height of fuel that can be stored in the sampling chamber 14, are determined by the upper end position of the partition wall 15, and both are the same height.

[0082] However, in this configuration, when the introduction of fuel into the sampling chamber 14 begins during refueling, the fuel in the sampling chamber 14 immediately passes over the upper end (upper limit height HH) of the partition wall 15 and begins flowing into the fuel storage chamber 13.Therefore, in the event of incorrect refueling, the incorrectly-fueled fuel will not only be mixed into the fuel in the sampling chamber 14, but will also be mixed into the fuel in the fuel storage chamber 13, making it necessary to discard not only the fuel in the sampling chamber 14 but also the fuel in the fuel storage chamber 13.

[0083] Therefore, in the embodiment shown in Figure 3, the residual height HL, which is the storage height of the fuel remaining in the sampling chamber 14 and sampled, is set to a predetermined lower height than the upper limit height HH of the fuel that can be stored in the sampling chamber 14, and a storage height variable mechanism 40 is provided which causes fuel to remain at the residual height HL in the sampling chamber 14 when not refueling, and which raises the storage height of the fuel in the sampling chamber 14 to the upper limit height HH when refueling.

[0084] As an arrangement structure of a fuel characteristic detection sensor equipped with such a variable storage height mechanism 40, in the embodiment shown in Figure 3, a recess 10c is provided in the bottom wall 10a of the fuel tank 10, and a partition wall 15 is provided that is raised from the upper edge of this recess 10c to a predetermined higher position than the opening position (FLmin) of the suction port 22 of the fuel supply pipe 21, and a sampling chamber 14 is formed by combining the space formed between the partition wall 15 and the side wall 10b of the fuel tank 10 and the space formed within the aforementioned recess 10c.

[0085] This allows the detection part 30a of the fuel characteristic detection sensor 30 to be accommodated within the recess 10c, so that the detection part 30a of the fuel characteristic detection sensor 30 can be positioned at a lower position than the lower limit position FLmin of the fuel liquid level in the fuel storage chamber 13 (the opening position of the suction port 22 of the fuel supply pipe 21).

[0086] The aforementioned variable storage height mechanism 40 is composed of a connecting pipe 41 that connects the fuel storage chamber 13 to the sampling chamber 14 at a position lower than the lower limit position FLmin of the liquid level in the fuel storage chamber 13 (the opening position of the suction port 22 of the fuel supply pipe 21), and an opening / closing valve 42 that opens and closes the connecting pipe 41.

[0087] As a result, when fuel is not being refueled, the opening / closing valve 42 of the variable storage height mechanism 40 is opened to connect the fuel storage chamber 13 and the sampling chamber 14 via the connecting pipe 41 at a position lower than the lower limit position FLmin, and when fuel is consumed in this state, the fuel liquid level in the sampling chamber 14 drops to the same height as the fuel liquid level FL in the fuel storage chamber 13, even due to the presence of the partition wall 15.

[0088] Therefore, as shown as "at consumption" in Figure 3, as an example, when the fuel liquid level FL in the fuel storage chamber 13 drops to the lower limit position FLmin, the liquid level of the fuel remaining in the sampling chamber 14 also drops to the same position.

[0089] Therefore, in this example, it is possible to sample the fuel remaining in the sampling chamber 14 at a residual height HL corresponding to the lower limit position FLmin.

[0090] From this state, when fuel supply is started by closing the on-off valve 42 of the variable storage height mechanism 40 to block communication between the fuel storage chamber 13 and the sampling chamber 14 via the connecting pipe 41, fuel can be stored in the sampling chamber 14 up to the upper limit height HH determined by the upper end position of the partition wall 15.

[0091] As a result, even in the event of mis-fueling, a certain amount of mis-fueled fuel (the capacity between HL and HH) can be stored in the sampling chamber 14, and by determining that mis-fueling has occurred while the mis-fueled fuel remains in the sampling chamber 14 and stopping the refueling operation, it is possible to prevent the mis-fueled fuel from being introduced into the fuel storage chamber 13.

[0092] As a result, even if erroneous refueling occurs, the fuel in the fuel storage chamber 13 can be used as is, and only the mixed fuel produced in the sampling chamber 14 needs to be disposed of, etc., which significantly reduces the amount of fuel to be disposed of, and even if erroneous refueling occurs while the engine is running, the erroneously refueled fuel will not be supplied to the engine.

[0093] The aforementioned opening / closing valve 42 provided in the variable storage height mechanism 40 may be operated, for example, so that it is closed every time the refueling worker refuels and opened when refueling is completed, or the opening / closing valve 42 may be configured, for example, as an electromagnetic valve that opens and closes automatically.

[0094] As an example of such a configuration, a soundproof box (not shown) of an engine-driven work machine may be provided with a fuel filler window (not shown) for accessing the fuel filler port 16 of the fuel tank 10, and a fuel filler door (not shown) for opening and closing the fuel filler window, and an opening / closing valve (solenoid valve) 42 may be operated in conjunction with a switch (not shown) that turns ON / OFF in accordance with the opening and closing of the fuel filler door, thereby opening the opening / closing valve 42 when the fuel filler door is closed (when not refueling) and closing the opening / closing valve 42 when the fuel filler door is open (when refueling).

[0095] The above describes the fuel characteristic detection sensor arrangement structure with reference to Figure 3, which is provided with a variable storage height mechanism 40 that enables the storage height of the fuel relative to the sampling chamber 14 to be varied. However, the fuel characteristic detection sensor arrangement structure shown in Figure 3 can also be configured without the variable storage height mechanism 40.

[0096] In this case, as in the embodiment described with reference to Figure 1, the residual height HL of the fuel remaining in the sampling chamber 14 to be sampled and the upper limit height HH of the fuel that can be stored in the sampling chamber 14 are both determined by the upper end position of the partition plate 15, and the two heights (HL, HH) are the same height.

[0097] In addition, in a configuration in which the sampling chamber 14 is provided at the lower side of the fuel tank 10 as described with reference to Figures 1 to 3, a guide plate 17 may be provided in the fuel tank 10 to guide the fuel supplied through the fuel filler port 16 toward the sampling chamber 14, as shown in Figures 4(A) and (B).

[0098] By providing such a guide plate 17, the fuel supplied through the fuel filler port 16 is guided into the sampling chamber 14, thereby preventing fuel from flowing into the fuel storage chamber 13 without passing through the sampling chamber 14.

[0099] In the above, the fuel characteristic detection sensor arrangement structure described with reference to Figures 1 to 4 has been described as a configuration in which the sampling chamber 14 is provided on the lower side within the fuel tank 10. However, instead of this configuration, a configuration in which the sampling chamber 14 is provided on the upper side within the fuel tank 10 as shown in Figures 5(A) and (B) may also be adopted.

[0100] Since refueling of the fuel tank 10 is normally performed when the amount of fuel remaining in the fuel tank 10 is low, even if a configuration is adopted in which the sampling chamber 14 is provided on the bottom side of the fuel tank 10 as described with reference to Figures 1 to 4, by starting refueling when the fuel liquid level FL in the fuel storage chamber 13 is below the upper end (upper limit height HH) of the partition plate 15, the fuel that has been supplied to the fuel tank 10 through the fuel supply port 16 at the start of refueling can be directly introduced into the sampling chamber 14.

[0101] However, in the configuration of Figures 1 to 4, when fuel remains in the fuel storage chamber 13 exceeding the upper end (upper limit height HH) of the partition wall 15, the sampling chamber 14 is submerged in the fuel stored in the fuel storage chamber 13 [see Figure 2 (A)], so if refueling is started in this state, the fuel supplied through the refueling port 16 cannot be directly introduced into the sampling chamber 14.

[0102] In this case, it becomes impossible to detect the occurrence of mis-fueling until a significant amount of the mis-fueled fuel has been mixed into the total fuel in the fuel tank 10, making it impossible to determine whether mis-fueling has occurred at an early stage.

[0103] In contrast, in a configuration in which the sampling chamber 14 is provided at the upper side of the fuel tank 10 as shown in Figure 5, even when a large amount of fuel remains in the fuel storage chamber 13, the fuel liquid level FL in the fuel storage chamber 13 is lower than the upper end position (upper limit height HH) of the side wall 15' of the sampling chamber 14, and the fuel supplied through the fuel filler port 16 can be directly introduced into the sampling chamber 14. This makes it possible to early determine the occurrence of refueling errors regardless of the fuel consumption status in the fuel storage chamber 13.

[0104] Furthermore, in a configuration in which the sampling chamber 14 is provided at the upper part of the fuel tank 10, the sampling chamber 14 can be provided at a position close to the fuel filler port 16, so that fuel can be reliably introduced into the sampling chamber 14 without providing an induction plate 17 or the like as in the embodiment described with reference to Figure 4.

[0105] As a configuration for providing a sampling chamber 14 at the upper part of the fuel tank 10 in this manner, in the embodiment shown in Figure 5, a bottomed box-shaped container that opens upward is attached to the upper end side of the side wall 10b of the fuel tank 10 below the fuel filler port 16, thereby forming the sampling chamber 14 inside this box-shaped container.

[0106] With this configuration, the fuel supplied through the fuel filler port 16 is first introduced into the sampling chamber 14, and any fuel that exceeds the upper end position (upper limit height HH) of the side wall 15' of the sampling chamber 14 flows into the fuel storage chamber 13, so that fuel can always remain in the sampling chamber 14 up to the upper end position of the side wall 15' (residual height HL = upper limit height HH) and be sampled.

[0107] Therefore, in the configuration shown in Figure 5, the upper end position of the side wall 15' of the sampling chamber 14 is the residual height HL of the fuel (fuel to be sampled) remaining in the sampling chamber 14, and at the same time, it determines the upper limit height HH of the fuel that can be stored in the sampling chamber 14, and the two heights HL and HH are set to be the same height.

[0108] Thus, even in the embodiment shown in Figure 5, the fuel supplied through the fuel fill port 16 at the start of refueling is introduced into the sampling chamber 14 and mixed with the relatively small amount of fuel sampled in the sampling chamber 14, and the fuel overflowing from the sampling chamber 14 flows into the fuel storage chamber 13.As a result, as in the embodiment described with reference to Figure 1, if mis-fueling occurs, even the mis-fueling of a relatively small amount of fuel can cause a significant change in the characteristics of the fuel in the sampling chamber 14.Therefore, by detecting the characteristics of the fuel in the sampling chamber 14 and monitoring those changes, it is possible to determine that mis-fueling has occurred very early after mis-fueling begins.

[0109] Furthermore, since a portion of the fuel supplied to the fuel tank 10 is always stored in the sampling chamber 14 up to the upper end position (residual height HL) of the side wall 15', as in the embodiment described with reference to Figure 1, by storing the detection portion 30a of the submerged fuel characteristic detection sensor 30 at a position lower than the residual height HL in the sampling chamber 14, the detection portion 30a of the fuel characteristic detection sensor 30 is not exposed above the fuel liquid surface.

[0110] In addition, even in a configuration in which the sampling chamber 14 is provided at the upper part of the fuel tank 10 as shown in Figure 5, a variable storage height mechanism 40 shown as a modified example in Figure 5 (B) may be provided to enable fuel to remain at a residual height HL in the sampling chamber 14 when the fuel tank 10 is not being refueled, and to raise the storage height of fuel in the sampling chamber 14 to an upper limit height HH defined by the upper end of the side wall 15' when refueling of the fuel tank 10 begins.

[0111] In the configuration shown as a modified example in Figure 5 (B), such a variable storage height mechanism 40 is provided, which includes a connecting pipe 41 having one end 41a connected to the sampling chamber 14 at a position higher than the upper end position of the detection section 30a of the fuel characteristic detection sensor 30, and the other end 41b connected to the fuel storage chamber 13 at a position equal to or lower than the one end 41a, and an opening / closing valve 42 for opening and closing this connecting pipe 41.

[0112] As a result, by keeping the opening / closing valve 42 of the variable storage height mechanism 40 open when not refueling, the height of the fuel that can be stored in the sampling chamber 14 is lowered to the opening position of one end 41a of the connecting pipe 41, and this position becomes the residual height HL of the fuel to be sampled in the sampling chamber 14.

[0113] On the other hand, when refueling, by closing the opening / closing valve 42 of the variable storage height mechanism 40, fuel can be stored in the sampling chamber 14 up to the upper end of the side wall 15', and the upper end position of the side wall 14' becomes the upper limit height HH of the fuel that can be stored in the sampling chamber 14.

[0114] As a result, even if mis-fueling occurs, a certain amount (volume between HL and HH) of the mis-fueled fuel can be stored in the sampling chamber 14, making it possible to determine that mis-fueling has occurred before the mis-fueled fuel flows into the fuel storage chamber 13.

[0115] The opening / closing valve 42 provided in the variable storage height mechanism 40 shown as a modified example in Figure 5 (B) may be operated manually to be opened and closed by the refueling worker, similar to the opening / closing valve 42 of the variable storage height mechanism 40 described with reference to Figure 3, or it may be formed by an electromagnetic valve and configured to open and close automatically, in which case it may be configured to open and close automatically in conjunction with the opening and closing operation of a refueling door provided in the soundproof box of the engine-driven work machine.

[0116] In the above, in the arrangement structure of the fuel property detection sensor described with reference to Figs. 1 to 5, the configuration in which the fuel storage chamber 13 and the sampling chamber 14 are provided in a single fuel tank 10 has been described.

[0117] In contrast, in the configuration shown in Figure 6, the fuel tank 10 is formed by combining a main tank 11 and a sub-tank 12, with the aforementioned fuel storage chamber 13 formed in the main tank 11 and the aforementioned sampling chamber 14 formed in the sub-tank 12.

[0118] A fuel fill port 16 is provided in the sub-tank 12 so that fuel supplied through the fuel fill port 16 can be introduced into a sampling chamber 14 formed in the sub-tank 12, and an exhaust port 12a provided at the upper end of the side wall of the sub-tank 12 is connected to an inlet port 11a provided at the upper end of the side wall of the main tank 11 so that the fuel introduced into the sampling chamber 14 can overflow from the sampling chamber 14 and be introduced into the fuel storage chamber 13.

[0119] With this configuration, the sampling chamber 14 formed in the subtank 12 can store fuel up to an upper limit height HH determined by the lower end position of the discharge port 12a, and can sample fuel by leaving it in the sampling chamber 14 up to a residual height HL determined by the lower end position of the discharge port 12a.Therefore, in the embodiment shown in Figure 6, the upper limit height HH of the fuel that can be stored in the sampling chamber 14 and the residual height HL of the fuel that remains in the sampling chamber 14 are the same height.

[0120] In addition, in the configuration shown in Figures 1 to 5, the fuel storage chamber 13 and the sampling chamber 14 are provided within a single fuel tank 10, so that the fuel remaining in the sampling chamber 14 among the fuel in the fuel storage chamber 13 is not supplied to the engine, resulting in a reduction in the amount of fuel that can be supplied to the engine.

[0121] In contrast, in a configuration as shown in Figure 6, in which a sub-tank 12 is provided separately from the main tank 11 and a sampling chamber 14 is formed within this sub-tank 12, the sampling chamber 14 is provided as a space separate from the fuel storage chamber 13, and therefore the provision of the sampling chamber 14 does not reduce the amount of fuel that can be supplied to the engine.

[0122] Furthermore, by forming the sampling chamber 14 within the sub-tank 12, the fuel tank of an existing engine-driven work machine can be used as the main tank 11, and by adding a new sub-tank 12 to it, it is possible to adopt the arrangement structure of the fuel characteristics detection sensor of the present invention, and the arrangement structure of the fuel characteristics detection sensor of the present invention can be easily adopted for existing engine-driven work machines.

[0123] In addition, even in the fuel characteristic detection sensor arrangement structure in which the fuel tank 10 is composed of the main tank 11 and the sub tank 12, a variable storage height mechanism 40 may be provided as shown as a modified example in Figure 6, so that fuel can remain in the sampling chamber 14 at a residual height HL when the fuel tank 10 is not being refueled, and the maximum storage height of fuel in the sampling chamber 14 can be raised to the upper limit height HH when refueling of the fuel tank 10 begins.

[0124] In the configuration shown as a modified example in Figure 6, such a variable storage height mechanism 40 is provided, which includes a connecting pipe 41 having one end 41a connected to the sub-tank 12 (sampling chamber 14) at a position higher than the upper end position of the detection section 30a of the fuel characteristic detection sensor 30 and the other end 41b connected to the main tank 11 (fuel storage chamber 13) at a height equal to or lower than the one end 41a, and an opening / closing valve 42 for opening and closing this connecting pipe 41.

[0125] As a result, by keeping the on-off valve 42 open when not refueling, fuel at a residual height HL determined by the opening position of one end 41a of the communicating pipe 41 remains in the sampling chamber 14 and is sampled, and by keeping the on-off valve 42 closed when refueling begins, the fuel supplied through the fuel supply port 16 can be stored up to an upper limit height HH determined by the lower end position of the outlet 12a of the sub-tank 12.

[0126] As a result, even if erroneous refueling occurs, a certain amount of the erroneously refueled fuel can be stored in the sampling chamber 14 (the volume between HL and HH), and by determining whether erroneous refueling has occurred during this time and stopping the refueling operation, the erroneously refueled fuel can be prevented from being introduced into the main tank 11 (fuel storage chamber 13).

[0127] Even in the modified example shown in Figure 6, the opening / closing valve 42 may be manually opened and closed by the refueling worker, or it may be an electromagnetic valve that opens and closes automatically.In this case, it may be configured to open and close automatically in conjunction with the opening and closing of a refueling door provided in a soundproof box of the engine-driven work machine. [Explanation of symbols]

[0128] 10. Fuel Tank 10a Bottom wall (of fuel tank) 10b Side wall (of fuel tank) 10c Depression (in fuel tank) 11 Main Tank 11a Inlet 12 Subtank 12a Outlet 13 Fuel Storage Room 14 Sampling Room 15 Partition Wall 15' side wall 16 Fuel filler 17 Guidance plate 21 Fuel supply pipe 22 Inlet (of fuel supply pipe) 24 Return pipe 30 Fuel property detection sensor 30a Detector 33 Drain outlet (for fuel storage room) 34 Drain outlet (sampling room) 40 Variable storage height mechanism 41 Communication pipe 41a one end 41b Other end 42 On-off valve 110 Fuel Tank 210c Depression (in fuel tank) 121 Fuel supply pipe 122 Intake (of fuel supply pipe) 130 Fuel property detection sensor 130a Detector 210 Fuel Tank 230 Sensors 230a Detector HL Residual height (of fuel relative to the sampling chamber) HH Upper limit height (of fuel that can be stored in the sampling chamber) FL Fuel level FLmax Upper limit (fuel level) FLmin Lower limit (fuel level)

Claims

1. In an engine-driven working machine having an engine and a fuel tank that supplies fuel to the engine through a fuel supply pipe, The fuel tank is provided with: a fuel storage chamber having an opening at an inlet of the fuel supply pipe; a sampling chamber formed as a small-volume space relative to the fuel storage chamber; A portion of the fuel already supplied to the fuel tank is sampled in the sampling chamber at a residual height that is a predetermined height that is equal to or higher than an opening position of the suction port of the fuel supply pipe; When refueling of the fuel tank is started, the fuel that has started to be refueled into the fuel tank is introduced into the sampling chamber and mixed with the fuel sampled in the sampling chamber, and then the fuel that has overflowed from the sampling chamber is introduced into the fuel storage chamber, A method for detecting fuel characteristics in an engine-driven working machine, comprising detecting predetermined characteristics of the fuel in the sampling chamber.

2. A detection portion of a submerged fuel characteristic detection sensor is accommodated in the sampling chamber at a position lower than the residual height, 2. A method for detecting fuel characteristics in an engine-driven working machine according to claim 1, wherein the characteristics of the fuel in the sampling chamber are detected by the fuel characteristic detection sensor.

3. 3. A method for detecting fuel characteristics in an engine-driven working machine according to claim 1, wherein the residual height is set to the same height as an upper limit height of the fuel that can be stored in the sampling chamber.

4. The residual height is set to a predetermined lower height than an upper limit height of the fuel that can be stored in the sampling chamber; When the fuel tank is not being filled with fuel, the sampling is performed by leaving fuel at the remaining height in the sampling chamber, and A method for detecting fuel characteristics in an engine-driven working machine as described in claim 1 or 2, characterized in that when refueling of the fuel tank begins, the storage height of the fuel in the sampling chamber is raised to the upper limit height, and the fuel that has begun to be supplied to the fuel tank is stored in the sampling chamber until it reaches the upper limit height.

5. An engine-driven working machine having an engine and a fuel tank that supplies fuel to the engine through a fuel supply pipe. The fuel tank is provided with: a fuel storage chamber having an opening at an inlet of the fuel supply pipe; a sampling chamber formed as a small-volume space relative to the fuel storage chamber; the sampling chamber is formed as a bottomed container-like space provided below a fuel filler port provided in the fuel tank and at a position where the fuel filled through the fuel filler port flows down, and is configured so that a portion of the fuel filled into the fuel tank is left inside the sampling chamber up to a residual height that is a predetermined height above the opening position of the suction port of the fuel supply pipe, and is sampled; the sampling chamber and the fuel storage chamber are communicated with each other, so that the fuel introduced into the sampling chamber through the fuel filler port can be overflowed from the sampling chamber and introduced into the fuel storage chamber; 2. A fuel characteristic detection sensor arrangement structure for an engine-driven working machine, wherein a detection portion of a fuel characteristic detection sensor for detecting a predetermined characteristic of fuel is accommodated within the sampling chamber.

6. The fuel characteristic detection sensor is a liquid-immersion type sensor, 6. An arrangement structure of a fuel property detection sensor in an engine-driven working machine according to claim 5, wherein said detection portion of said fuel property detection sensor is accommodated in said sampling chamber at a position lower than said residual height.

7. 7. A fuel characteristic detection sensor arrangement structure for an engine-driven working machine according to claim 5, wherein the residual height is set to the same height as an upper limit height of the fuel that can be stored in the sampling chamber.

8. The residual height is set to a predetermined lower height than an upper limit height of the fuel that can be stored in the sampling chamber; An arrangement structure of a fuel characteristic detection sensor in an engine-driven working machine as described in claim 5 or 6, characterized in that a variable storage height mechanism is provided which allows fuel to remain at the residual height in the sampling chamber when the fuel tank is not being refueled, and which raises the storage height of fuel in the sampling chamber to the upper limit height when refueling of the fuel tank begins.

9. 7. The fuel characteristic detection sensor arrangement structure for an engine-driven working machine according to claim 5 or 6, characterized in that both the sampling chamber and the fuel storage chamber are provided within a single fuel tank, and the sampling chamber is provided on the bottom side within the fuel tank.

10. 10. The fuel characteristic detection sensor arrangement structure for an engine-driven working machine according to claim 9, further comprising an induction plate provided in the fuel tank for guiding fuel supplied through the fuel filler opening toward the sampling chamber.

11. 7. The fuel characteristic detection sensor arrangement structure for an engine-driven working machine according to claim 5 or 6, characterized in that both the sampling chamber and the fuel storage chamber are provided within a single fuel tank, and the sampling chamber is provided on the upper side within the fuel tank.

12. The fuel tank is formed by combining a main tank serving as the fuel storage chamber and a sub-tank serving as the sampling chamber, The sub-tank is provided with the fuel filler port, 7. The fuel characteristic detection sensor arrangement structure in an engine-driven working machine as described in claim 5 or 6, characterized in that an outlet provided at the upper end of the side wall of the sub-tank is connected to an inlet provided at the upper end of the side wall of the main tank.

Images