Fuel injection device for hand-held power tool

Abstract

A hand-held construction device (100) comprising a crankcase-scavenged internal combustion engine (110) arranged to drive a working tool (120), where a first mass (170) of the device (100) comprises the internal combustion engine (110), where a second mass (180) of the device (100) is vibrationally disengaged from the first mass (170) by one or more resilient members (160), where the second mass (180) is vibrationally disengaged from the first mass (170) by one or more resilient members (160). A fuel injector (230) is configured to provide a controlled amount of fuel to an air and fuel intake flow (210) of the internal combustion engine (110), the fuel injector being disposed in the second mass (180) and separated from the first mass (170) by one or more resilient members (160).

Description

Technical Field

[0001] The present disclosure relates to improved fuel injection devices and controls therefor for hand-held power tools such as power cutters, chain saws, and other power tools. Background Art

[0002] A power cutter is a hand-held construction device designed for cutting hard materials such as concrete and stone by means of a rotatable abrasive cutting disc. A power cutter is typically driven by a crankcase scavenged two-stroke internal combustion engine.

[0003] Chain saws are also typically driven by a crankcase scavenged two-stroke internal combustion engine. Depending on the type of saw chain, chain saws can be used to cut both wood and concrete.

[0004] Traditional carburettor designs are common in these types of implements. However, fuel injection systems, which include fuel injectors fed by a fuel pump, are becoming more and more common in power cutters and chain saws, as well as other types of hand-held power tools.

[0005] EP2602470 discloses an exemplary crankcase scavenged two-stroke engine in which fuel is injected directly into the crankcase.

[0006] EP2414665 describes another exemplary crankcase scavenged two-stroke engine in which fuel is injected directly into the combustion chamber.

[0007] Despite the progress made to date, there remains a desire for further improvements in power tools such as construction equipment for machining concrete and stone, as well as further improvements in power tools for machining softer materials like wood. Summary of the invention

[0008] An object of the present disclosure is to provide an improved fuel system for hand-held power tools, such as power cutters, chain saws and other power tools. This object is achieved at least in part by the features set out in the appended claims.

[0009] This object can be achieved at least in part by a power tool such as a handheld construction device, which includes a crankcase scavenged internal combustion engine arranged to drive a working tool. The first mass of the device includes the internal combustion engine, and the second mass of the device is vibrationally decoupled from the first mass by one or more elastic members. A fuel injector supplied by a fuel pump is configured to provide a controlled amount of fuel to the air and fuel intake flow of the internal combustion engine. The fuel injector is arranged in the second mass and is therefore separated from the first mass by one or more elastic members. This means that the fuel injector is away from the high-temperature internal combustion engine, which is an advantage. The fuel injector is also subject to a reduced amount of vibration compared to, for example, the case where the fuel injector is directly mounted on the crankcase of the internal combustion engine. The fuel injector can be separated from the internal combustion engine by several centimeters or more, such as greater than 3cm or even greater than 5cm.

[0010] The second mass of the device may include at least one handle by which an operator guides the device during use. This is a common division between the vibrating and non-vibrating parts of a power cutter. By arranging the fuel injector in the handle portion of the machine, the fuel injector is subjected to lower temperatures and less vibration. The fuel injector device may also be arranged in a smaller second mass, which substantially only includes the fuel injector subsystem. In this case, the device optionally also includes a third mass, which is vibrationally decoupled from at least one of the first and second masses, wherein the third mass includes at least one handle by which an operator guides the device during use.

[0011] The air and fuel intake flow of the internal combustion engine is optionally transferred from the second mass to the first mass through a non-rigid tubular passage. The non-rigid passage does not transfer a lot of vibration from the first mass to the second mass, and the non-rigid passage also makes it easier to assemble the fuel system connections between the first mass and the second mass. The non-rigid tubular passage is also less sensitive to vibrations that might otherwise cause material fatigue in rigid passage connections and the like. An integrally formed fuel system module including the injector and other related parts can be assembled separately and installed in a handheld power tool by attaching the non-rigid tubular passage in a convenient manner.

[0012] The fuel injector is preferably integrated in the valve housing part together with the throttle valve of the handheld power tool. Thus, a fuel and air subsystem can be formed which can be assembled separately from the rest of the machine and efficiently installed in a single piece. The integrated valve housing part can also be designed in a space-efficient manner, which is an advantage in handheld power tools and construction equipment where space is often limited.

[0013] At least one gas head channel (i.e. a passage for pure air to enter the internal combustion engine) optionally extends from the second mass to the first mass, wherein a fuel injector is arranged in connection with at least one gas head channel. The first gas head channel and the second gas head channel preferably extend from the second mass to the first mass, and the fuel injector is advantageously arranged between the first gas head channel and the second gas head channel, wherein the fuel injector is cooled and arranged in a compact, space-efficient manner. The integrated valve housing may optionally further comprise one or more gas head channels. The one or more gas head channels may optionally be controlled by the same throttle valve as the air and fuel intake flow, thereby providing a particularly compact design.

[0014] The fuel injector can be mounted on the upper side or the lower side of the fuel intake flow path. In the case where the fuel injector is mounted on the upward side of the air and fuel intake flow of the internal combustion engine, a controlled amount of fuel is injected in a downward direction when the device is maintained in the normal operating position. This means that gravity provides an auxiliary effect when the fuel enters the air and fuel intake flow of the internal combustion engine from the nozzle of the fuel injector. In the case where the fuel injector is mounted on the downward side of the air and fuel intake flow of the internal combustion engine, a controlled amount of fuel is injected in a direction having a component in the upward direction when the device is maintained in the normal operating position. This mounting of the fuel injector may be suitable due to the overall machine geometry. The advantage is that the arrangement of the fuel injector in the second mass can be chosen relatively freely.

[0015] An electronic control unit (ECU) is configured to control the fuel injectors and is also preferably arranged in the second mass, where cooling requirements are lower and where the ECU is also subject to less vibrations which could be harmful to electrical connectors and circuitry of the ECU.

[0016] At least one fuel line extends from a fuel pump of the power tool to a fuel injector and may also be enclosed in the second mass where it is protected from strong vibrations.

[0017] The present disclosure also relates to an idle air passage, which is arranged to be connected to the air and fuel intake flow of an internal combustion engine downstream of a throttle valve, and is arranged to be connected to a fuel injector. The idle air passage provides a constant airflow when the machine is running, and the airflow not only inhales fuel from the fuel injector toward the internal combustion engine, but also cools the fuel injector. In order to improve the cooling effect, the idle air passage can be guided along a portion of the fuel injector and then connected to the air and fuel intake flow of the internal combustion engine. This prolongs the contact time between the idle air and the fuel injector, thereby improving the heat transfer between the fuel injector and the idle airflow. In order to further improve the cooling effect, the fuel injector optionally includes a cooling flange portion, and the idle air passage is guided along the cooling flange portion and then connected to the air and fuel intake flow of the internal combustion engine. The cooling flange portion preferably forms a portion of the idle passage wall so that the idle airflow passes through the cooling flange of the fuel injector.

[0018] The control valve can also be arranged in the idle air passage to adjust the air flow of the idle air passage. The control valve can of course be operated manually. However, if the control valve is arranged to be adjusted based on a control signal from the ECU of the device, additional advantages can be obtained. In this way, automatic optimization of the idle operation of the internal combustion engine can be achieved. The control valve can also be used to open the idle air passage to prepare for the start of the internal combustion engine, when increasing the amount of air can be beneficial. Once the internal combustion engine has been started and is running normally, the idle air passage returns to the rated idle air flow state. The handheld power tool can, for example, include an electronically controlled idle screw, which is arranged to control the air flow in the idle air flow passage based on a control signal from a control unit (such as the above-mentioned ECU). The control unit can then increase the air flow in the idle air flow passage by the electronically controlled idle screw during the starting operation to improve the starting performance of the internal combustion engine.

[0019] The handheld power tool optionally includes an electronically controlled throttle valve arranged to control the air and fuel intake flow into the internal combustion engine based on a control signal from a control unit (such as the above-mentioned ECU). The electronically controlled throttle valve can be used to optimize various operations of the power tool, as described in WO 20200027708A1 and other prior art.

[0020] The ECU may be arranged to restrict the air and fuel intake flow into the engine by electronically controlling the throttle valve if the engine speed does not meet the engine speed acceptance criteria (such as if the engine speed exceeds a predetermined maximum engine speed threshold). This function is often referred to as a cut-off function and may be conveniently implemented in this manner.

[0021] The ECU may also be arranged to increase air and fuel intake flow into the internal combustion engine above idle air flow levels via the electronically controlled throttle valve during start-up of the internal combustion engine.

[0022] The electronically controlled throttle valve is advantageously arranged in series with the manually controlled throttle valve to control the air and fuel intake flow into the internal combustion engine. By arranging the two throttle valves in series, a redundant scheme is achieved that increases the safety of the power tool. The operator can, for example, use a trigger 145 connected to the manually controlled throttle valve to control the internal combustion engine (as in conventional products), and the electronically controlled throttle valve can add automatic control functions to the power tool. The manually controlled throttle valve can be arranged as a mechanically controlled throttle valve that is connected to the trigger 145, or as a second electronically controlled throttle valve that is arranged to be controlled at least in part based on the state of the trigger 145.

[0023] The manual control throttle valve may include a starting boost hole configured to allow starting boost air flow through the manual control throttle valve in the closed position. In this way, the electronically controlled throttle valve can increase air flow during the starting process of the internal combustion engine, which is an advantage.

[0024] According to some aspects, the manually controlled throttle valve and the electronically controlled throttle valve are mechanically coupled to each other so that the position of the electronically controlled throttle valve at least partially determines the position of the manually controlled throttle valve. This mechanical linkage can be used to increase the airflow into the internal combustion engine during the starting operation, which is an advantage. The mechanical coupling can, for example, be based on cooperating cams arranged on the respective valve axes of the throttle valves, or on some other form of mechanical coupling structure.

[0025] Generally, unless otherwise clearly defined herein, all terms used in the claims will be interpreted according to their common meanings in the technical field. Unless otherwise clearly stated, all references to "one / a kind of / the element, device, part, device, step, etc." will be openly interpreted as referring to at least one instance of the element, device, part, device, step, etc. Unless clearly stated, the steps of any method disclosed herein do not have to be performed in the exact order disclosed. When studying the attached claims and the following description, further features and advantages of the present invention will become apparent. The technician will recognize that, without departing from the scope of the present invention, the different features of the present invention can be combined to produce embodiments other than the embodiments described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present disclosure will now be described in more detail with reference to the accompanying drawings, in which:

[0027] Figure 1A to Figure 1BTwo exemplary power cutter designs are shown;

[0028] Figure 2 An exemplary fuel system for a handheld power tool is shown;

[0029] FIG. 3A to FIG. 3B An exemplary fuel system for a handheld power tool is shown;

[0030] FIG. 4A to FIG. 4B An exemplary fuel system for a handheld power tool is shown;

[0031] Figure 5 A fuel / air supply system for an internal combustion engine is schematically shown;

[0032] Figure 6 An example of supplying idle air to an internal combustion engine is shown;

[0033] FIG. 7A to FIG. 7B An exemplary fuel system for a handheld power tool is shown;

[0034] FIG. 8A to FIG. 8B The valve status during the start-up and idling of the internal combustion engine is shown;

[0035] FIG. 9A to FIG. 9B shows exemplary valve states during operation of an internal combustion engine;

[0036] FIG. 10A to FIG. 10B The electronically adjustable idle air passage is shown;

[0037] Fig.11 A system of mechanically coupled throttle valves is shown;

[0038] FIG. 12A to FIG. 12B shows exemplary valve operation during the start-up process of the engine;

[0039] FIG. 13A to FIG. 13B Other exemplary valve operations during engine startup are shown; and

[0040] FIG. 14A to FIG. 14C An exemplary fuel system for a handheld power tool is shown. DETAILED DESCRIPTION

[0041] The present invention will now be described more fully below with reference to the accompanying drawings, which illustrate certain aspects of the present invention. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments and aspects set forth herein; rather, these embodiments are provided by way of example so that the present disclosure will be thorough and complete and fully convey the scope of the present invention to those skilled in the art. Throughout the description, the same reference numerals refer to the same elements.

[0042] It is to be understood that the present invention is not limited to the embodiments described herein and shown in the drawings; rather, the skilled person will recognize that many changes and modifications are possible within the scope of the appended claims.

[0043] Figure 1A and Figure 1B Two examples of power cutters are shown, which are examples of handheld power tools 100 for cutting hard material work objects (such as concrete and stone). The techniques and arrangements presented herein are particularly applicable to construction equipment such as power cutters, but can also be applied to chain saws and other handheld power tools. Therefore, although the technology disclosed herein will be primarily exemplified by power cutters, it should be recognized that the technology disclosed herein for providing fuel and air to a crankcase scavenged internal combustion engine can generally be applied to other types of tools, such as chain saws, hedge trimmers and other handheld power tools.

[0044] Figure 1A to Figure 1B The power cutter in the embodiment of the present invention comprises an internal combustion engine 110 which is arranged to drive a working tool 120, here in the form of a rotatable circular abrasive cutting tool, via a drive device included in a power cutter tool arm 125. During use, the operator guides the machine using a front handle 130 and a rear handle 140. The front handle 130 extends transversely to the plane of the rotatable cutting disc and is closer to the tool 120 than the rear handle 140.

[0045] The fuel tank 150 stores fuel for driving the internal combustion engine 110. The internal combustion engine 110 is operated by a mixture of the fuel from the fuel tank 150 and the air from the air intake 240, and the internal combustion engine generally includes an air filter 115, such as Figure 1A and Figure 1B As shown in , the air filter is arranged to filter air to remove particles and other impurities.

[0046] In the exemplary power cutter 100, a first mass 170 of the device 100 includes the internal combustion engine 110, and a second mass 180 of the device 100 is provided by one or more elastic elements (such as Figure 1A The steel spring 160 (shown as an insert in FIG. 1 ) is vibrationally decoupled from the first mass 170. Rubber bushings or other types of vibration-damping elastic elements may also be used to vibrationally isolate the first mass from the second mass. The distance between the first mass and the second mass is generally referred to as the vibration gap and may be of the order of 1 cm or so. The technology for vibrationally isolating two or more masses of a power tool from each other is already known, see for example SE359250, and is therefore not discussed in detail herein.

[0047] exist Figure 1AIn the example of FIG. 1 , the first mass 170 of the power cutter includes the internal combustion engine 110 and the cutting tool 120, and the second mass 180 of the power cutter includes the handle parts 130, 140 (the connection between the front handle 130 and the second mass 180 is Figure 1A In this example, the fuel tank 150 is also part of the second mass 180 .

[0048] exist Figure 1B In the example of , the second mass 180 is smaller and comprises only a portion of the fuel injection system to be discussed below. The handle portions 140, 130 then form part of a third mass 190 which also comprises the fuel tank 150. In this example, the second mass 180 is vibrationally isolated from the first mass 170 by an elastic member in the form of a bushing. The third mass 190 is Figure 1A A steel spring 160 or other vibration-damping element (such as an elastomeric bushing or the like) of the type shown in FIG. 1 is vibrationally isolated from the first mass and, therefore, also from the second mass.

[0049] The at least two masses 170, 180 of the power tool 100 are vibrationally isolated from each other to prevent vibrations generated by the internal combustion engine 110 and / or by the cutting tool 120 from propagating to other parts of the machine, such as the handle portions 130, 140. The exemplary power cutter 100 also includes an electronic control unit (ECU) 220, a fuel injector 230, and passages for directing an air and fuel mixture to the internal combustion engine 110. These components will be discussed in detail below.

[0050] In both examples, the ECU 220 is positioned directly in connection with the air intake 240. Thus, the ECU 220 benefits from some of the cooling effects of the airflow in the air intake. The ECU 220 is also located at a vibration-clearance distance from the internal combustion engine 110 and is therefore less affected by the heat generated by the internal combustion engine 110 during use of the machine.

[0051] Because crankcase scavenged internal combustion engines have a high power-to-weight ratio and low complexity, they are often used for appliances such as power cutters. Such engines traditionally include a carburettor for supplying fuel to the engine. However, fuel injection systems including a fuel pump and a fuel injector are becoming more common. For example, EP2602470 discloses an exemplary crankcase scavenged two-stroke engine in which fuel is injected into the crankcase. It is often desirable to arrange the fuel injector as close to the combustion chamber as possible, as this allows for a faster response to changes in the timing or amount of fuel injection.

[0052] A problem with mounting the fuel injector close to the engine, such as in EP2602470 where the fuel injector is mounted directly on the crankcase, is that high temperatures are typically present at this location and relatively strong vibrations of the internal combustion engine 110 are also generated at this location.

[0053] Vapor lock is a problem caused by the conversion of liquid fuel to a gaseous state in the fuel delivery system of an internal combustion engine. This may disrupt the operation of the internal combustion engine and may also make it more difficult to restart the internal combustion engine. For this and other reasons, it is necessary to maintain low temperatures at the fuel injectors. Reducing the temperature of the fuel injectors can be achieved, for example, by active cooling using airflow and / or by placing the fuel injectors at a location away from heat sources (i.e., high temperature internal combustion engines). Active cooling improves the operating conditions of the fuel injector system during machine operation, but of course this active cooling is ineffective when the machine is shut down, when problems with residual thermal transients occur. Placing the fuel injectors at a location away from heat sources effectively reduces the temperature of the fuel injectors during operation and when the machine is shut down, but traditionally has avoided the problems associated with the increased distance between the injector location and the combustion chamber.

[0054] Fuel injectors typically include electrical components, such as mechanically delicate solenoid valves with electrical wiring connections, which may be sensitive to prolonged exposure to vibration. Therefore, there is also a need to limit the amount of vibration that a fuel injector is subjected to during use.

[0055] Figure 2 Shows the application Figure 1A and Figure 1B 200 for a power cutter in FIG. A fuel injector 230 is arranged in the second mass 180 (i.e., in a non-vibrating portion of the power cutter), which is connected to the main combustion gas flow from the air intake 240. Thus, the fuel injector 230 is separated from the internal combustion engine 110 by a vibration isolation element that bridges the vibration gap between the first mass 170 and the second mass 180. This arrangement of the fuel injector has several benefits. First, the fuel injector is now away from the high-temperature internal combustion engine 110 and is therefore subject to much lower temperatures than, for example, the case where the fuel injector is mounted directly on the crankcase or in the cylinder head of the engine 110. This lower temperature alleviates problems such as vapor lock. In addition, arranging the fuel injector 230 in a non-vibrating portion of the power cutter means that the fuel injector (and in particular its electrical connections) is subject to much less vibration than the case where the fuel injector is mounted in a vibrating portion of the power cutter.

[0056] Combustion air is directed from the surrounding environment into the air intake 240 through the air filter 115. At least one throttle valve 250 is arranged in the main combustion air flow to adjust the amount of air supplied to the internal combustion engine 110. The throttle valve is usually controlled by the machine trigger 145 on the rear handle 140, but can also be an electronically controlled throttle valve, as will be discussed in detail below. The fuel injector 230 is arranged downstream of the throttle valve 250, where it distributes a controlled amount of fuel into the air and fuel intake flow 210 of the engine. Figure 2 A more detailed view of the fuel injector in Figure 3B The engine's air and fuel intake flow 210 is transferred from the second mass 180 to the first mass 170 in part through a non-rigid passage 260 (i.e., a rubber hose, etc.) that terminates at one or more ports formed in the cylinder wall of the internal combustion engine 110 (not shown in the figure).

[0057] The head passage (also called the air passage for stratified scavenging) is an air passage through which clean air (without fuel) flows intermittently into the combustion chamber. During the intake phase of a crankcase scavenged two-stroke internal combustion engine with stratified scavenging, clean air is supplied through one or more head passages through ports in the cylinder wall. The clean air flow fills the scavenging duct to fill the scavenging duct with fuel-free air. During the same intake phase, the fuel and air mixture is supplied to the crankcase through the air and fuel intake passage. During the scavenging phase of the internal combustion engine, due to stratified scavenging, the initial air flow entering the cylinder from the scavenging duct is mainly clean air. Then, in the later stage of the scavenging phase, the fuel-containing air from the crankcase enters the combustion chamber with the clean air. The late entry of fuel into the combustion chamber limits the scavenging losses of unburned fuel into the exhaust, thereby reducing the emissions of the internal combustion engine. In this example, there are two head passages 310, 320, which form part of the air and fuel intake flow 210. Techniques for stratified scavenging are generally known and therefore not discussed in detail herein.

[0058] In conclusion, Figure 1A to Figure 1B and Figure 2 An example of a handheld power tool 100 is shown, which includes a crankcase scavenged internal combustion engine 110, which is arranged to drive a working tool 120. A first mass 170 of the device 100 includes the internal combustion engine 110, and a second mass 180 of the device 100 is vibrationally decoupled from the first mass 170 by one or more resilient members 160. The second mass 180 may include only some components of the internal combustion engine air / fuel system, such as Figure 1B exemplified in, or only includes a larger part of the equipment, such as Figure 1AThus, it will be appreciated that a power tool may comprise two or more masses, wherein at least a first mass and a second mass are vibrationally isolated from one another.

[0059] A fuel injector 230 is configured to provide a controlled amount of fuel to the air and fuel intake flow 210 of the internal combustion engine 110, and is disposed in the second mass 180 and separated from the first mass 170 by one or more resilient members. The fuel injector 230 is supplied by a fuel pump 280. The air and fuel intake flow 210 of the internal combustion engine 110 is preferably transferred from the second mass 180 to the first mass 170 through a non-rigid tubular passage 260 (such as a rubber hose or the like). This non-rigid passage reduces the amount of vibration transferred between the masses, which is an advantage. The non-rigid tubular passage 260 also simplifies machine assembly because many components can be assembled separately into a single subsystem, such as Figure 2 and then integrated with the rest of the machine.

[0060] The fuel injector is traditionally arranged near the internal combustion engine, that is, directly arranged on the crankcase or connected to the cylinder head of the engine. This arrangement is usually to keep the distance between the fuel injector and the combustion chamber as small as possible. However, the position close to the internal combustion engine is also associated with temperature increase and strong vibration, which is a disadvantage. By arranging the fuel injector 230 in the second mass 180, the fuel injector is away from the internal combustion engine 110 and is vibrated and separated from the internal combustion engine 110, thereby reducing the temperature of the fuel injector and better protecting the fuel injector from strong vibration. Since the larger distance between the fuel injector and the internal combustion engine has been avoided traditionally, this arrangement may seem unintuitive and contrary to good performance. However, in this particular case, it has been found that the performance degradation caused by the distance between the fuel injector and the combustion chamber is acceptable. The length of the non-rigid tubular passage connecting the fuel injector system to the internal combustion engine is a few centimeters to the order of about 20cm. In a preferred embodiment, the distance between the fuel injector and the internal combustion engine is at least 2cm, and preferably greater than 5cm.

[0061] An additional advantage of the present fuel injection device is that it enables the apparatus 100 to be constructed in a modular manner. By integrating the fuel injector with the inlet of the throttle valve and the air filter, a compact fuel / air subsystem can be designed that is easy to assemble with the rest of the machine. An electronically controlled throttle valve can also be arranged in series with a manually controlled throttle valve and formed integrally with the fuel / air subsystem. The electronically controlled valve allows for more advanced optimization of the operation of the internal combustion engine, such as the functionality discussed in WO20200027708A1.

[0062] According to one example discussed above, the second mass 180 of the device 100 includes at least one handle 130, 140 by which the operator guides the device 100 during use. In this case, the first mass 170 can be vibrationally decoupled from the second mass 180 by one or more metal springs or rubber bushings that bridge the vibration gap between the two masses. This type of vibration decoupling is common in handheld internal combustion engine-driven construction equipment, where vibrations from the internal combustion engine 110 and / or from the work tool 120, if fully transmitted to the handles 130, 140, may cause discomfort or even injury to the operator of the device 100. The second mass 180 may also include a fuel tank for storing fuel.

[0063] According to another example discussed above, the device 100 also includes a third mass 190 that is vibrationally decoupled from at least one of the first mass 170 and the second mass 180. The third mass 190 includes at least one handle 130, 140 by which an operator guides the device 100 during use. In this case, the second mass 180 can be vibrationally decoupled from the first mass by a rubber bushing or other vibration-damping element that holds the second mass in place relative to the first mass. The non-rigid tubular passage 260 also serves to vibrationally decouple the second mass 180 from the first mass 170. An advantage associated with this manner of assembling the entire machine is that the fuel injection system can be formed as a single subsystem and efficiently assembled with the rest of the machine by means of a resilient mount.

[0064] The ECU 220 is configured to control the fuel injector 230 and is optionally arranged in the second mass 180. This arrangement of the ECU is advantageous because the ECU is protected from strong vibrations, which would otherwise be harmful to the ECU. In addition, the electrical control line extending from the ECU 220 to the fuel injector 230 can now be enclosed in the second mass, or at least the electrical connector of the electrical control line is enclosed at the fuel injector end. Therefore, the electrical connector is protected from strong vibrations, and the electrical control line extending to the fuel injector does not need to pass between the first mass 170 and the second mass 180. It should also be noted that the ECU 220 is arranged to be connected to the air and fuel intake flow 210, where the ECU is partially cooled by air, and the fuel injector 230 and the ECU 220 are also arranged on opposite sides of the air and fuel intake flow 210, thereby making the configuration of the components compact. According to some aspects, the ECU 220 is also arranged to generate a control signal for controlling an electronically controlled throttle valve of a power tool. The electronically controlled throttle valve will be discussed in more detail below.

[0065] Figure 2Some additional components of the fuel injection system 200 are also shown. The stator 270 is optionally arranged to be connected to the rotor fixed to the motor shaft, and thus obtain electrical energy for powering, for example, the ECU 220 and the fuel injector 230 solenoid valve. The ECU 220 controls the fuel injection process (including timing) and sometimes configures the amount of fuel distributed into the air and fuel intake flow 210 based at least in part on data received from the motor sensor 275. The motor sensor can, for example, provide data related to combustion pressure, various temperature readings associated with the internal combustion engine 110, and also related to the motor shaft speed. The motor sensor data can also be used to control the electronically controlled throttle valve.

[0066] The fuel pump 280 delivers fuel to the fuel injectors 230 at an operating pressure. The operating pressure of the fuel pump is typically fixed, but may also be controlled by the ECU 220 in some cases, providing an additional degree of freedom to optimize the combustion process. For example, the fuel pressure may be measured, and the ECU 220 may then use the pressure information to compensate for pressure variations in the fuel supply. According to some aspects, at least one fuel line 285 extending from the fuel pump 285 to the fuel injectors 230 is enclosed in the second mass 180. This means that since the fuel line is away from the internal combustion engine, the fuel line is protected from harmful vibrations and high temperatures, which is an advantage. The fuel pump may also be located Figure 1B In the third mass 190 shown in FIG. 1 , in this case the fuel line passes between the third mass 190 and the second mass 180 , both masses being vibrationally decoupled from the first mass 170 .

[0067] Furthermore, a stop button 285 is connected to the ECU 220 , and wiring connected to the internal combustion engine ignition device 290 also extends from the ECU to the internal combustion engine 110 .

[0068] FIG. 3A to FIG. 3B and FIG. 4A to FIG. 4B Two examples of valve housings 300 , 400 are shown with an integrated fuel injector 230 which may be advantageously used in power tools such as power cutters, hedge trimmers, fan blowers and chain saws. Figure 3A and Figure 4A A stereogram is shown, while Figure 3B and Figure 4B A cross-sectional view is shown. Figure 3A and Figure 3B The layout and Figure 1A and Figure 1B is similar to the arrangement shown in Figure 4A and Figure 4B The design shown in is an alternative design in which the fuel injector 230 is arranged on the downward D side of the throttle valve arrangement and the air passage.

[0069] The two exemplary valve housings 300, 400 include an input aperture 330 that forms part of the air intake 240 of the internal combustion engine system of the apparatus 100. Some type of air filter is typically arranged upstream of the valve housing. Figure 1A and Figure 1B An exemplary air filter 115 is discussed. A throttle valve 250 controls the amount of air provided to the internal combustion engine in a known manner. It should be appreciated that one or more throttle valves may be used in series or in parallel. For example, one throttle valve may be manually controlled and another throttle valve may be electronically controlled by the ECU 220 to optimize internal combustion engine operation during use of the apparatus 100. The manually controlled throttle valves discussed herein are typically spring biased toward a closed position so that the valves automatically close when the operator does not actuate the trigger 145.

[0070] The fuel injector 230 may be integrated with the throttle valve 250 of the handheld power tool 100 in the valve housing portion or at least positioned close to the valve housing portion (at a distance of 5 mm to 30 mm), thereby providing a compact design with high mechanical integrity, such as FIG. 3A to FIG. 3B and FIG. 4A to FIG. 4B as shown in .

[0071] FIG. 3A to FIG. 3B and FIG. 4A to FIG. 4B Also shown are optional head passages 310, 320 extending from the valve housing toward the internal combustion engine 110. The head passages are passages that supply pure air from the intake port 240 to the internal combustion engine 110. The head passages terminate at corresponding head ports formed in the cylinder wall. The arrangement of these head ports allows entry from the head passages into the cylinders as part of the scavenging operation before the fuel and air mixture enters the cylinders, thereby reducing emissions from the internal combustion engine 110. Head systems for crankcase scavenged internal combustion engines are generally known and are therefore not discussed in detail herein.

[0072] At least one gas head passage 310, 320 extends from the second mass 180 to the first mass 170. In particular, the fuel injector 230 is arranged in connection with the at least one gas head passage 310, 320. Therefore, since the temperature of the fuel injector needs to be kept low, the relatively cool air in the gas head passage provides cooling for the fuel injector, which is an advantage.

[0073] A single head passage extending from the second mass 180 to the first mass 170 may also be provided. The single head passage may then terminate at a branch arranged to connect to the cylinder wall of the internal combustion engine 110, for example, or at a single head port formed in the cylinder wall of the internal combustion engine 110.

[0074] like FIG. 3A to FIG. 3B and FIG. 4A to FIG. 4BAs illustrated in FIG. 1 , the design may include a first gas head passage 310 and a second gas head passage 320 extending from the second mass 180 to the first mass 170. The fuel injector 230 is then preferably disposed between the first gas head passage 310 and the second gas head passage 320, where it is cooled and mechanically supported by the gas head passage passages.

[0075] For example FIG. 3A to FIG. 3B and FIG. 4A to FIG. 4B The fuel injector 230 shown in FIG. 1 intersects a vertical plane (when the apparatus 100 is in a normal operating position) that separates the first gas head passage 310 and the second gas head passage 320 from each other. FIG. 3A to FIG. 3B The upper mounted fuel injectors and FIG. 4A to FIG. 4B The lower mounted fuel injector intersects.

[0076] It will be appreciated that the plane need not be strictly vertical. Substantial benefits are also achieved with designs of substantially vertical separation planes, such as where the plane deviates from exact vertical by an angle of within 5 to 10 degrees.

[0077] The normal operating position refers to the orientation of the machine during normal use. The orientation of the machine in the normal operating position is substantially equivalent to the orientation of the machine when at rest, ie when the machine is not in use and supported on the ground in the rest position. Figure 1A and Figure 1B The machine shown in can be said to be in the normal operating position.

[0078] The internal combustion engine 110 is generally a single cylinder engine and has a cylinder bore for a reciprocating piston. A vertical plane intersects the central axis of the cylinder bore at right angles.

[0079] The arrangement in which the substantially vertical plane intersects the fuel injector may also be advantageously used for power tools that do not include two or more vibration isolating masses 170, 180. In other words, the present disclosure also relates to a handheld power tool 100 comprising a crankcase scavenged internal combustion engine 110 arranged to drive a working tool 120, wherein a fuel injector 230 of the device 100 is arranged upstream of and remote from the internal combustion engine 110. The fuel injector may be remote from the internal combustion engine, for example, by some form of passage, such as a rigid passage or a non-rigid passage, for example a tubular passage 260. Remote means more than 5 cm apart or at least not directly attached. The handheld power tool 100 comprises a first gas head channel 310 and a second gas head channel 320, for example FIG. 3A to FIG. 3B and FIG. 4A to FIG. 4B As shown in FIG. 1 , they are arranged to direct pure air to the internal combustion engine 110. The fuel injector 230 intersects the substantially vertical plane separating the first gas head passage 310 and the second gas head passage 320.

[0080] According to some aspects, the fuel injector 230 is arranged above (in direction U) the air and fuel intake flow 210 of the internal combustion engine 110 in the normal operating position (or rest position) of the handheld power tool 100. The normal operating position is discussed above. Figure 1A to Figure 1B As shown in FIG. 1 , the normal operating position is essentially an upright position of the device 100 .

[0081] The ECU 220 is configured to control the fuel injector 230. The ECU 220 also intersects the vertical plane, and the ECU is advantageously arranged below the air and fuel intake flow 210 in the normal operating position of the handheld power tool 100, while the first air head channel 310 and the second air head channel 320 are arranged above the fuel intake flow 210 in the normal operating position of the handheld power tool 100.

[0082] Of course, this arrangement may also be supplemented by vibrationally isolated first and second masses, as generally discussed herein, in which case the fuel injector 230 is preferably arranged in the second mass 180 and remote from the internal combustion engine 110 .

[0083] The present invention also discloses a handheld power tool 100, which includes a crankcase scavenging internal combustion engine 110, which is arranged to drive a working tool 120, wherein a fuel injector 230 of the device 100 is configured to provide a controlled amount of fuel to an air and fuel intake flow 210 of the internal combustion engine 110; wherein the fuel injector 230 is arranged upstream of and away from the internal combustion engine 110 in the normal operating position of the handheld power tool 100 in question, and is basically arranged above the air and fuel intake flow 210, wherein the handheld power tool 100 includes at least one air head channel 310, 320, and wherein the air head channels 310, 320 are basically arranged above the fuel intake flow 210 in the normal operating position of the handheld power tool 100 and at the position of the injector 230.

[0084] It should be noted that the throttle valve 250 is arranged to control the air and fuel intake flow 210 and the flow through the at least one gas head passage 310, 320, ie the throttle valve is a common valve for both the air and fuel flow and the gas head flow.

[0085] In order to improve the flexibility of the non-rigid passage 260, bellows-like portions 340, 345 are arranged downstream of the valve housing. These bellows-like portions increase the flexibility of the non-rigid passage, thereby making it easier to attach the non-rigid passage at the end points. Figure 1BWhere subsystems 300, 400 are used in the designs shown in FIG. 3 , the bellows-like portions 340, 345 also increase vibration isolation between the first mass and the second mass.

[0086] FIG. 3A to FIG. 3B The fuel injector 230 in the embodiment is mounted on the upward U side of the air and fuel intake flow 210 of the internal combustion engine 110, and thus a controlled amount of fuel is injected in a downward direction D when the device is maintained in the normal operating position. An advantage associated with this arrangement is that gravity provides an assisting effect when the fuel is injected into the air and fuel intake flow of the internal combustion engine 110. Alternatively, the fuel injector 230 can be mounted on the downward D side of the air and fuel intake flow 210 of the internal combustion engine 110, and a controlled amount of fuel is injected in a direction I having a component in the upward direction U when the device 100 is maintained in the normal operating position, such as Figure 4B 1 , the upward direction U is where the front handle 130 is located, and the downward direction D is where the machine is supported on the ground.

[0087] Figure 2 , FIG. 3A to FIG. 3B as well as FIG. 4A to FIG. 4B An example of an integrally formed fuel system module 200, 300, 400 suitable for use with a crankcase scavenged two-stroke internal combustion engine of the type discussed herein is shown. The module comprises a plurality of components having complex interdependencies and is integrally formed into a single unit which is then easily assembled with the remainder of the apparatus 100.

[0088] The module includes an input hole 330 for allowing a clean air flow to enter the fuel system module. The input hole can be designed, for example, to connect to the air filter 115 of the device or some other form of main air inlet. The central cavity 360 is optionally arranged to be connected to the input hole 360. One or more gas head channel holes 380 are arranged to connect to the corresponding gas head channels 310, 320 for guiding clean air out of the fuel system module. Therefore, the fuel system module supports stratified scavenging. If stratified scavenging is not required, these holes can be sealed. The fuel and air mixture hole 390 is arranged to connect to the passage 260 (such as the non-rigid passage discussed above, of course, the passage does not have to be non-rigid) for guiding the fuel and air mixture out of the fuel system module. The throttle valve 250 is arranged to control the clean air flow from the input hole 330 to one or more gas head channel holes 380 and the fuel and to the air mixture hole 390. The fuel injector seat is arranged to receive the fuel injector 230 and defines a bore connected to the fuel injector seat that leads to a passage 260 for directing the fuel and air mixture out of the fuel system module.

[0089] This highly compact fuel system module can be assembled separately from the rest of the apparatus 100 and then conveniently installed as a single integrated module. This simplifies assembly of the entire system, which is an advantage.

[0090] The integrally formed fuel system module 200, 300, 400 optionally also includes means 370 for attaching the ECU 220 to the fuel system module. This means that the ECU can also be preassembled with the components of the fuel system to produce a compact preassembled unit. A cable harness 235 is arranged between the ECU 220 and the fuel injector 230 received by the fuel injector seat, which cable harness can then also be preassembled.

[0091] By forming an integral fuel system module, many complex fuel system components can be assembled separately from the rest of the apparatus 100 and then installed in a simple modular fashion. If the connections to the engine (i.e., the head passages 310, 320 and passage 260) are non-rigid, the additional advantage of a flexible passage that is easier to connect at the end points is obtained.

[0092] Figure 5 The components of the air and fuel intake flow 210 of an internal combustion engine are schematically shown. The purpose of the air and fuel intake flow is to provide the combustion chamber of the internal combustion engine 110 with a suitable fuel and air mixture. The air and fuel intake flow begins at the air intake 240 of the machine, where ambient air is drawn into the system. The ambient air is usually filtered at an early stage through an air filter 115 to remove particles and other impurities, such as Figure 1A and Figure 1B250. The air intake on some machines also includes additional air cleaning devices, such as a centrifugal system for separating larger particles from the incoming air. The main combustion air flow channel 510 passes through the throttle valve 250, and the air flow in the main combustion air flow channel 510 is controlled by the position of the throttle valve 250. The air flow component determines the operating point of the internal combustion engine, as discussed in WO20200027708A1. Generally, the more air is allowed to pass through the main combustion air flow channel 510, the higher the output power of the internal combustion engine 110. An idle air flow channel 520 is also provided. The air flow provides the air required for the internal combustion engine to operate during idle operation and is not controlled by the throttle valve 250. When the machine is running with the throttle fully open (full throttle), the idle air flow in the idle air flow channel 520 is usually much smaller than the main combustion air flow of the main combustion air flow channel 510. In some cases, the idle air flow is achieved by not completely closing the throttle valve at the throttle zero position (zero throttle). The manually controlled throttle valve may, for example, include a small hole or be prevented from being completely closed by a stopper, so that an airflow greater than the desired idle airflow is allowed to pass through the manually controlled throttle valve. This allows the idle airflow level and the airflow during the start-up of the internal combustion engine to be controlled by opening and closing the electronically controlled throttle valve to adjust the airflow during different operating processes. However, additional advantages can be obtained by passing the idle airflow through a separate passage, as will be discussed below.

[0093] The idle air flow passage 520 is optionally arranged to connect to the air and fuel intake flow 210 of the internal combustion engine 110 downstream of the throttle valve 250, and is arranged to connect to the output of the fuel injector 230 (close to the location where the fuel from the fuel injector enters the intake flow 210). According to some aspects of the present disclosure, the idle air flow is arranged to connect to the air and fuel intake flow 210 of the internal combustion engine 110 and is within 0 mm to 10 mm of the nozzle of the fuel injector.

[0094] Since the idle air flow passage 520 is connected to the air and fuel intake air flow 210 where the nozzles of the fuel injectors are located, the idle air flow from the idle air passage cools the fuel injectors, thereby alleviating problems such as vapor lock, etc. In addition, the idle air flow draws fuel toward the internal combustion engine chamber, thereby effectively preventing the formation of fuel pools in the air and fuel intake air flow path, which may cause uneven idling of the internal combustion engine 110.

[0095] like Figure 6 As shown in FIG. 1 , the idle air flow passage 520 may also be directed along a portion 630 of the fuel injector 230 and then connected to the air and fuel intake flow 210 of the internal combustion engine 110. As described above, the idle air flow 610 leaving the idle air flow passage 520 may also be configured to pass through the output 620 of the fuel injector 230, such as Figure 6 As shown in , the idle airflow pushes the fuel from the injector 230 in the general direction of the air and fuel intake airflow 210, which is desired. The idle airflow through the fuel injector transports heat away from the injector and thus improves the cooling effect of the injector. Since the fuel is effectively transported to the main combustion airflow passage 510 by the idle airflow 610 from the idle airflow passage 520, the fuel delivery effect of the internal combustion engine 110 is also improved. The fuel injector 230 may also include a cooling flange portion, along which the idle airflow passage 520 can be guided and then connected to the air and fuel intake airflow 210 of the internal combustion engine 110.

[0096] It should be noted that the idle air passage configuration relative to the location of the fuel injector can be achieved even if the fuel injector is located in the first mass 170. Therefore, a power tool 100 is also disclosed herein, which includes a crankcase scavenged internal combustion engine 110, which is arranged to drive a work tool 120, wherein the fuel injector 230 is configured to provide a controlled amount of fuel to the air and fuel intake flow 210 of the internal combustion engine 110, and wherein the idle air flow passage 520 is arranged to connect with the air and fuel intake flow 210 of the internal combustion engine 110 and is arranged to connect with the fuel injector 230. The idle air flow passage 520 is optionally guided along a portion 630 of the fuel injector 230 and then connected to the air and fuel intake flow 210 of the internal combustion engine 110. The fuel injector 230 optionally further includes a cooling flange portion, wherein the idle air flow passage 520 is guided along the cooling flange portion and then connected to the air and fuel intake flow 210 of the internal combustion engine 110 .

[0097] Figure 6 Also shown is an idle speed control valve 640 arranged in the idle air flow passage 520, which is used to adjust the air flow of the idle air passage, i.e., to calibrate the operation of the internal combustion engine during idling. The idle speed control valve 640 can of course be manually configurable. However, if the idle speed control valve 640 is arranged to be adjusted based on a control signal from an ECU of the device 100 (such as the ECU 220 discussed above), additional advantages can be obtained. The ECU can then be configured to adjust the idle speed control valve 640 by using the above combined Figure 2 The motor sensor 275 is discussed to measure the motor shaft speed to adjust the idle control valve 640 according to a preconfigured target idle speed, etc. The idle control valve 640 is often referred to as an idle screw, even though the idle screw does not necessarily include a threaded portion.

[0098] The hand-held power tool 100 and the integrally formed fuel system module discussed above may include an electronically controlled idle screw 1000, such as FIG. 10A to FIG. 10BAs shown in the example of . The electronically controlled idle screw 1000 is arranged to control the airflow in the idle airflow channel 520 based on a control signal from a control unit (such as ECU 220). ECU 220 can, for example, be arranged to increase the idle airflow during the start-up process of the internal combustion engine to improve the starting performance of the internal combustion engine. The electronically controlled idle screw 1000 can be actuated by a solenoid or similar actuator device that can be electronically controlled by ECU 220. Since the electronically controlled idle screw 1000 is in a position associated with increased airflow when the solenoid is de-energized (such as usually before the power tool 100 is started), it is advantageous to use a solenoid to push the spring-loaded idle screw mechanism into a closed position (i.e., to push the spring-loaded idle screw mechanism away from a position associated with increased airflow in the idle airflow channel 520).

[0099] Figure 6 The idle air flow arrangement shown in may optionally be included in the integrally formed fuel system module discussed above. FIG. 10A to FIG. 10B The idle air flow device shown in is also optionally included in the integrally formed fuel system module discussed above. The idle air flow adjustment device discussed herein can be used alone and can also obtain advantages without the other technical features disclosed herein.

[0100] WO20200027708A1 discusses several technical functions and features that can be achieved by adding an electronically controlled throttle valve to an internal combustion engine air and fuel system. The features discussed in WO20200027708A1 are also applicable here. For example, FIG. 7 shows an exemplary fuel system 700 including an electronically controlled throttle valve 255, which is arranged to control the air and fuel intake flow 210 based on a control signal from the ECU 220 or from some other throttle controller in the system. The electronically controlled throttle valve 255 can be used as the only throttle valve in the fuel system, or in series with a manually controlled throttle valve 250 to control the air and fuel intake flow 210 entering the internal combustion engine 110. Figure 7B An exemplary fuel system is shown that includes a manually controlled throttle valve 250 in series with an electronically controlled throttle valve 255. Placing a manually controlled throttle valve in series with an electronically controlled throttle valve in this manner increases reliability.

[0101] A servo or other electrical actuator 710 may be used to control the state of the electronically controlled throttle valve 255. The actuator 710 is then connected to the ECU 220 or some other control unit via a cable 720. The cable 720 may, for example, extend to the ECU 220 mounted to connect to the fuel system, such as Figure 2. The electronically controlled throttle valve 255 may be arranged as a continuously controllable valve, wherein the opening may be continuously controlled from a closed position to a fully open position (or between other end points of the valve, such as between a half-closed valve position and a half-open valve position). The electronically controlled throttle valve 255 may also be arranged as a discretely stepped controllable valve, which may be gradually controlled from a closed position to an open position. Some electronically controlled valves have only two states, fully open or fully closed. It should be noted that Figure 7B The valve plates in the embodiment are overlapped 730, ie the distance between the rotation axes 740, 750 of the valves is less than the diameter of the valve plates. This is a space efficient way of mounting two valves in series. Figure 7B The valve disc in is shown in the fully open position and rotates counterclockwise to the fully closed position, as shown in FIG. Figure 7B As shown by the arrows R1 and R2. FIG. 12A to FIG. 12B and 13A to Fig. 13B The manually controlled throttle valve in the example is biased toward a closed position, as is customary for manually controlled throttle valves in devices of this type.

[0102] During the process of starting the engine 110 from rest, it may be necessary to provide some additional air in the air and fuel intake flow 210. Then, once the engine has started and is operating normally, this additional amount of air can be removed and the engine returned to the operating state of the rated idle air flow, which is configured, for example, by the idle screw 640 or by a combination of adjustment of the orifice in the manually controlled throttle valve and the electronically controlled throttle valve.

[0103] According to some aspects, the manually controlled throttle valve 250 includes a starter pressurization hole 251, such as Fig. 8A and Figure 8B As exemplified in Fig.11 The start-up boost hole 251 is configured to allow the start-up boost airflow f h The charge air flow f is started by manually controlling the throttle valve 250 in the closed position. h is the total airflow through the fuel system during the start-up process of the internal combustion engine and is greater than the rated idle airflow. Since the manually controlled throttle valve 250 always allows the start-up boost airflow to pass, the idle airflow can be temporarily increased by the electronically controlled throttle valve 255. This concept can be used with or without a separate idle airflow channel 520. Therefore, the ECU 220 or some other control unit can be arranged to control the electronically controlled throttle valve 255 to increase the air and fuel intake airflow 210 during the start-up process of the internal combustion engine 110 by opening the electronically controlled throttle valve 255, such as Fig. 8AAs soon as the internal combustion engine has started correctly and is running smoothly, the electronically controlled throttle valve 255 can be closed again, whereupon the airflow is reduced to the rated idle airflow f l <f h , and the internal combustion engine 110 returns to the configured idle operating state, such as Figure 8B as shown in .

[0104] For example, if the fuel system includes only a single electronically controlled throttle valve and does not include a manually controlled throttle valve in series with the electronically controlled throttle valve, the ECU 220 may also be arranged to increase the air and fuel intake flow 210 to above the idle air flow level only through the electronically controlled throttle valve 255 during the start-up process of the internal combustion engine 110.

[0105] The ECU 220 may also be arranged to restrict the air and fuel intake flow 210 by electronically controlling the throttle valve 255 if the speed of the internal combustion engine 110 does not meet the engine speed acceptance criteria, i.e. perform a cut-off operation to reduce the internal combustion engine speed to a value below a maximum speed threshold etc. Fig.9A In the fuel system, the fuel system is operated in the wide open throttle (WOT) state, when both the manual control throttle valve and the electronic control throttle valve are fully open. Fig. 10A In the main combustion air flow channel 510, the air flow Fig. 9B has been reduced, for example for reducing the speed of the internal combustion engine 110. This cut-off function has been discussed in detail in WO20200027708A1 and is therefore not discussed in detail herein.

[0106] Fig.11 An exemplary fuel system is shown in which a manually controlled throttle valve 250 and an electronically controlled throttle valve 255 are mechanically coupled 1100 to one another such that the position of the electronically controlled throttle valve 255 at least partially determines the position of the manually controlled throttle valve 250. It will be appreciated that such mechanical linkage between the two valves may be achieved in a variety of different ways. Fig.11 An exemplary mechanical coupling between the manually controlled throttle valve 250 and the electronically controlled throttle valve 255 in FIG. 1 includes cooperating cams 1110, 1120 disposed on respective valve axes 1130, 1140 of the manually controlled throttle valve 250 and the electronically controlled throttle valve 255. These cams engage to bias the position of the manually controlled throttle valve away from (toward a fully closed state).

[0107] The exemplary mechanical coupling is arranged to bring the manually controlled throttle valve 250 into a partially open position when the electronically controlled throttle valve 255 is in the first open position 1200, such as Fig. 12A and Fig.13A, where the first open position is a fully open position or a nearly fully open position of the electronically controlled throttle valve 255. The exemplary mechanical coupling is also arranged to bring the manually controlled throttle valve 250 into a closed position when the electronically controlled throttle valve 255 is in the second open position 1210, as shown in FIG. Fig. 12B and Fig. 13B , where the second open position is a partially open position of the electronically controlled throttle valve 255. It should be noted that the difference in opening of the electronically controlled throttle valve 255 between the operating positions 1200 and 1210 is typically very small and is slightly exaggerated in the drawings.

[0108] FIG. 14A to FIG. 14C An exemplary fuel system similar to some of the fuel system modules described above is shown, wherein a manually controlled throttle valve 250 is arranged in series with an electronically controlled throttle valve 255, and wherein a fuel injector 230 is located downstream of both throttle valves 250, 255. In this example, the throttle valves control air into the header passages and also control air into the main combustion air flow passages.

[0109] The first partition wall 1400 is arranged in connection with the manually controlled throttle valve 250 and the electronically controlled throttle valve 255 to separate at least the gas head passages 310, 320 from the main combustion gas flow passage 510. The first partition wall prevents fuel from escaping from the main combustion gas flow passage and entering the gas head passage. The fuel injector 230 is arranged downstream of the throttle valve and also prevents fuel from entering the gas head passage.

[0110] In most of the examples discussed herein, the fuel injectors are arranged downstream of the manually controlled throttle valve and also downstream of the electronically controlled throttle valve. This is an advantage because it reduces the amount of fuel leaking into one or more gas head passages. It can also reduce the problem of back spray. In most of the examples, the fuel injectors are also arranged upstream of the internal combustion engine and away from the internal combustion engine, i.e., the fuel injectors are not arranged to inject fuel directly into the crankcase or combustion chamber.

[0111] Most of the exemplary hand-held power tools discussed herein also include a second partition wall that is arranged in connection with and downstream of the fuel injector 230 and between at least one gas head passage 310, 320 and the main combustion gas flow passage 510, as shown in a number of drawings. The second partition wall 350 effectively prevents fuel from the fuel injector 230 from entering the at least one gas head passage 310, 320.

[0112] The present disclosure generally describes and illustrates a handheld power tool 100 that includes a crankcase scavenged internal combustion engine 110 that is arranged to drive a work tool 120, wherein a fuel injector 230 is configured to provide a controlled amount of fuel to an air and fuel intake flow 210 of the internal combustion engine 110, as discussed above. The power tool 100 includes an electronically controlled throttle valve 255 that is arranged to control the air and fuel intake flow 210 based on a control signal from an ECU 220, the electronically controlled throttle valve being arranged in series with a manually controlled throttle valve 250, wherein the fuel injector 230 is arranged downstream of the manually controlled throttle valve 250 and the electronically controlled throttle valve 255.

[0113] According to various aspects, the electronically controlled throttle valve 255 and the manually controlled throttle valve 250 are both arranged to control the airflow in the main combustion gas flow channel 510 and the airflow in one or more gas head channels 310, 320. Therefore, the throttle valve arrangement is configured for stratified scavenging, wherein the two throttle valves affect the airflow in the main combustion gas flow channel and the airflow in one or more gas head channels. An optional first partition wall 1400 can be arranged to be connected to the manually controlled throttle valve 250 and the electronically controlled throttle valve 255 to separate at least one gas head channel 310, 320 from the main combustion gas flow channel 510. The first partition wall improves the separation effect between the one or more gas head channels and the main combustion gas flow channel. The fuel injector 230 is preferably arranged downstream of the manually controlled throttle valve 250 and the electronically controlled throttle valve 255.

Claims

1. A hand-held power tool (100) comprising a crankcase-scavenged internal combustion engine (110) arranged to drive a working tool (120), in, The first mass (170) of the device (100) comprises the internal combustion engine (110), wherein the second mass (180) of the device (100) is vibratedly separated from the first mass (170) by one or more elastic members (160), wherein a fuel pump (280) is arranged to deliver fuel to a fuel injector (230), wherein the fuel injector (230) is configured to provide a controlled amount of fuel to an air and fuel intake flow (210) of the internal combustion engine (110), Therein, the fuel injector (230) is arranged in the second mass (180) and is thus separated from the first mass (170) by the one or more elastic members (160).

2. The handheld power tool (100) according to claim 1, wherein: The second mass (180) of the device (100) includes at least one handle (130, 140) by which an operator guides the device (100) during use.

3. The handheld power tool (100) according to claim 1, wherein: The device (100) further comprises a third mass (190) which is vibrationally decoupled from at least one of the first mass (170) and the second mass (180), wherein the third mass (190) comprises at least one handle (130, 140) by which an operator guides the device (100) during use.

4. The handheld power tool (100) according to any one of the preceding claims, wherein: The air and fuel intake flow (210) of the internal combustion engine (110) is transferred from the second mass (180) to the first mass (170) through a non-rigid tubular passage (260).

5. The handheld power tool (100) according to any one of the preceding claims, wherein: The fuel injector (230) is integrated with a throttle valve (250, 255) of the handheld power tool (100) in a valve housing portion.

6. The handheld power tool (100) according to any one of the preceding claims, wherein: At least one gas head passage (310, 320) extends from the second mass (180) to the first mass (170), wherein the fuel injector (230) is arranged in connection with the at least one gas head passage (310, 320).

7. The handheld power tool (100) according to claim 6, wherein: The at least one gas head channel (310, 320) extends from the second mass (180) to the first mass (170) and terminates in a branch arranged to connect to a cylinder wall of the internal combustion engine (110).

8. The handheld power tool (100) according to claim 7, comprising a first gas head passage and a second gas head passage (310, 320) extending from the second mass (180) to the first mass (170), wherein: The fuel injector (230) is arranged between the first gas head passage and the second gas head passage (310, 320).

9. The handheld power tool (100) according to claim 8, wherein: The fuel injector (230) intersects a substantially vertical plane that separates the first and second gas head passages (310, 320).

10. The handheld power tool (100) according to any one of claims 6 to 9, wherein: A common throttle valve (250, 255) is arranged to control the air and fuel intake flow (210) and the flow through the at least one gas head passage (310, 320).

11. The handheld power tool (100) according to any one of the preceding claims, wherein: The fuel injector (230) is mounted (300) on the upward (U) side of the air and fuel intake flow (210) of the internal combustion engine (110), wherein a controlled amount of fuel is injected in a downward direction (D) when the device is maintained in a normal operating position.

12. The handheld power tool (100) according to any one of claims 1 to 10, wherein: The fuel injector (230) is mounted (400) on the downward (D) side of the air and fuel intake flow (210) of the internal combustion engine (110), wherein the controlled amount of fuel is injected in a direction (I) having a component in an upward direction (U) when the device (100) is maintained in a normal operating position.

13. The handheld power tool (100) according to any one of the preceding claims, wherein: An electronic control unit, ECU (220), configured to control the fuel injector (230) is arranged in the second mass (180).

14. The handheld power tool (100) according to claim 13, wherein: An electronic control line (235) enclosed in the second mass (180) extends from the ECU (220) to the fuel injector (230).

15. The handheld power tool (100) according to any one of the preceding claims, wherein: At least one fuel line (285) extends from a fuel pump (285) of the power tool (100) to the fuel injector (230), wherein the fuel line (285) is enclosed in the second mass (180) and / or in the third mass (190).

16. The handheld power tool (100) according to any one of the preceding claims, wherein: An idle air flow passage (520) is arranged to be connected to the air and fuel intake flow (210) of the internal combustion engine (110) downstream of the throttle valve (250, 255) and is arranged to be connected to the fuel injector (230).

17. The handheld power tool (100) according to claim 16, wherein: The idle airflow passage (520) is directed along a portion (630) of the fuel injector (230) prior to connection with the air and fuel intake flow (210) of the internal combustion engine (110).

18. The handheld power tool (100) according to claim 17, wherein: The fuel injector (230) includes a cooling flange portion, and wherein the idle airflow passage (520) is directed along the cooling flange portion before connecting with the air and fuel intake airflow (210) of the internal combustion engine (110).

19. The handheld power tool (100) according to any one of claims 16 to 18, wherein: An idle speed control valve (640) is arranged in the idle speed air flow channel (520) or upstream of the idle speed air flow channel to adjust the air flow of the idle speed air flow channel, wherein the idle speed control valve (640) is arranged to be adjusted based on a control signal from an ECU (220) of the device (100).

20. The handheld power tool (100) according to any one of the preceding claims, wherein: The power tool is a power cutter and wherein the working tool is a rotatable abrasive cutting disc, or wherein the power tool is a chain saw and wherein the working tool is a saw chain.

21. A handheld power tool (100) according to any one of the preceding claims, comprising an ECU (220) arranged in connection with the air and fuel intake flow (210), wherein: The fuel injector (230) and the ECU (220) are arranged on opposite sides of the air and fuel intake flow (210).

22. A handheld power tool (100) according to any one of the preceding claims, comprising an electronically controlled throttle valve (255) arranged to control the air and fuel intake flow (210) based on a control signal from an ECU (220).

23. The handheld power tool (100) according to claim 22, wherein: The ECU (220) is arranged to restrict the air and fuel intake flow (210) via the electronically controlled throttle valve (255) if the speed of the internal combustion engine (110) does not meet an engine speed acceptance criterion.

24. The handheld power tool (100) according to claim 22 or 23, wherein: The ECU (220) is arranged to increase the air and fuel intake flow (210) above an idle flow level via the electronically controlled throttle valve (255) during start-up of the internal combustion engine (110).

25. The handheld power tool (100) according to any one of claims 22 to 24, wherein: The electronically controlled throttle valve (255) is arranged in series with the manually controlled throttle valve (250) to control the air and fuel intake flow (210) into the internal combustion engine (110).

26. The handheld power tool (100) according to claim 25, wherein: The manually controlled throttle valve (250) includes a starting boost hole (251) configured to allow a starting boost airflow to pass through the manually controlled throttle valve (250) in a closed position, wherein the starting boost airflow is greater than a rated idle airflow of the handheld power tool (100).

27. The handheld power tool (100) according to claim 26, wherein: The ECU (220) is arranged to control the electronically controlled throttle valve (255) to increase the air and fuel intake flow (210) during start-up of the internal combustion engine (110).

28. The handheld power tool (100) according to any one of claims 25 to 27, wherein: The manually controlled throttle valve (250) and the electronically controlled throttle valve (255) are mechanically coupled to each other (1100) such that the position of the electronically controlled throttle valve (255) at least partially determines the position of the manually controlled throttle valve (250).

29. The handheld power tool (100) according to claim 28, wherein: The mechanical connection between the manually controlled throttle valve (250) and the electronically controlled throttle valve (255) comprises cooperating cams (1110, 1120) arranged on respective valve axes (1130, 1140) of the manually controlled throttle valve (250) and the electronically controlled throttle valve (255).

30. The handheld power tool (100) according to claim 28 or 29, wherein: The mechanical linkage is arranged to bring the manually controlled throttle valve (250) into a partially open position when the electronically controlled throttle valve (255) is in a first open position (1200).

31. The handheld power tool (100) according to any one of claims 28 to 30, wherein: The mechanical linkage is arranged to bring the manually controlled throttle valve (250) into a closed position when the electronically controlled throttle valve (255) is in a second open position (1210).

32. The handheld construction device (100) according to any one of claims 25 to 31, wherein: The fuel injector (230) is arranged downstream of the manually controlled throttle valve (250) and the electronically controlled throttle valve (255).

33. The handheld construction equipment (100) according to any one of claims 25 to 32 comprises a first partition wall (1400), which is arranged to be connected to the manually controlled throttle valve (250) and the electronically controlled throttle valve (255) to separate at least one gas head channel (310, 320) from the main combustion air flow channel (510).

34. A handheld power tool (100) according to any one of the preceding claims, comprising an electronically controlled idle screw (1000), which is arranged to control the airflow in the idle airflow channel (520) based on a control signal from an ECU (220).

35. The handheld power tool (100) according to claim 34, wherein: The ECU (220) is arranged to increase the airflow in the idle airflow passage (520) via the electronically controlled idle screw (1000) during startup of the internal combustion engine (110).

36. A hand-held power tool (100) comprising a crankcase scavenged internal combustion engine (110) arranged to drive a working tool (120), in, a fuel injector (230) configured to provide a controlled amount of fuel to an air and fuel intake flow (210) of the internal combustion engine (110), and Wherein, an idle air flow passage (520) is arranged to be connected to the air and fuel intake flow (210) of the internal combustion engine (110) connected to the fuel injector (230).

37. The handheld power tool (100) according to claim 36, wherein: The idle airflow passage (520) is directed along a portion (630) before the fuel injector (230) connects with the air and fuel intake airflow (210) of the internal combustion engine (110).

38. The handheld power tool (100) according to claim 36 or 37, wherein: The fuel injector (230) includes a cooling flange portion, and wherein the idle airflow passage (520) is directed along the cooling flange portion before connecting with the air and fuel intake airflow (210) of the internal combustion engine (110).

39. A hand-held power tool (100) comprising a crankcase scavenged internal combustion engine (110) arranged to drive a working tool (120), in, The fuel injector (230) of the device (100) is arranged upstream of the internal combustion engine (110) and remote from the internal combustion engine, The handheld power tool (100) comprises a first air head passage and a second air head passage (310, 320) arranged to guide pure air to the internal combustion engine (110), and The fuel injector (230) intersects a vertical plane that separates the first gas head passage and the second gas head passage (310, 320).

40. The handheld power tool (100) according to claim 39, in, The fuel injector (230) is arranged above the air and fuel intake flow (210) of the internal combustion engine (110) in a normal operating position of the handheld power tool (100), wherein an electronic control unit, ECU (220) is configured to control the fuel injector (230), wherein the ECU (220) intersects the vertical plane in the normal operating position of the handheld power tool (100) and is arranged substantially below the air and fuel intake flow (210), and Wherein, in the normal operating position of the handheld power tool (100), the first gas head channel and the second gas head channel (310, 320) are arranged above the air and fuel intake flow (210) of the internal combustion engine (110).

41. The handheld power tool (100) according to claim 39 or 40, in, The first mass (170) of the device (100) comprises the internal combustion engine (110), wherein the second mass (180) of the device (100) is vibratedly separated from the first mass (170) by one or more elastic members (160), and Wherein, the fuel injector (230) is arranged in the second mass (180).

42. The handheld power tool (100) according to any one of claims 39 to 41, wherein: The power tool is a power cutter and wherein the working tool is a rotatable abrasive cutting disc, or wherein the power tool is a chain saw and wherein the working tool is a saw chain.

43. A hand-held power tool (100) comprising a crankcase-scavenged internal combustion engine (110) arranged to drive a working tool (120), in, The fuel injector (230) of the apparatus (100) is configured to provide a controlled amount of fuel to an air and fuel intake flow (210) of the internal combustion engine (110), wherein, in a normal operating position of the handheld power tool (100), the fuel injector (230) is arranged upstream of and away from the internal combustion engine (110) and above the air and fuel intake flow (210), Wherein, the handheld power tool (100) comprises an air head channel (310, 320), Wherein, in the normal operating position of the handheld power tool (100), the gas head passage (310, 320) is arranged substantially above the fuel intake air flow (210) at the position of the injector (230).

44. The handheld power tool (100) according to claim 43, wherein: The power tool is a power cutter and wherein the working tool is a rotatable abrasive cutting disc, or wherein the power tool is a chain saw and wherein the working tool is a saw chain.

45. An integrally formed fuel system module (200, 300, 400, 600) for a crankcase scavenged two-stroke internal combustion engine (110), the module comprising: an input port (330) for allowing a clean air flow into the fuel system module, One or more gas head passage holes (380) arranged to connect with corresponding gas head passages (310, 320) for guiding clean air out of the fuel system module, a fuel and air mixture hole (390) arranged to connect with the passage (260) for directing the fuel and air mixture out of the fuel system module, a throttle valve (250, 255) arranged to control the flow of said clean air from said input aperture (330) to said one or more head passage apertures (380) and to said fuel and air mixture aperture (390), and A fuel injector seat is arranged to receive a fuel injector (230), wherein a hole leading to the passage (260) for directing the fuel and air mixture out of the fuel system module is formed in connection with the fuel injector seat.

46. ​​The integrally formed fuel system module (200, 300, 400, 600) of claim 45, further comprising means (370) for attaching an electronic control unit, ECU (220), to the fuel system module.

47. The integrally formed fuel system module (200, 300, 400, 600) of claim 46, further comprising a cable harness (235) disposed between the ECU (220) and a fuel injector (230) received at the fuel injector seat.

48. An integrally formed fuel system module (200, 300, 400, 600) according to any one of claims 45 to 47, wherein: An idle air flow passage (520) is arranged to connect the input hole (330) to the fuel and air mixture hole (390) downstream of the throttle valve (250, 255) and connected to the fuel injector seat.

49. An integrally formed fuel system module (200, 300, 400, 600) according to any one of claims 45 to 48, comprising an electronically controlled throttle valve (255) arranged to control the clean gas flow based on a control signal from an ECU (220).

50. The integrally formed fuel system module (200, 300, 400, 600) of claim 49, wherein: The electronically controlled throttle valve (255) is arranged in series with the manually controlled throttle valve (250) to control the clean air flow.

51. A handheld power tool (100) comprising an electronic control unit, ECU (220), an internal combustion engine (110), and an electronically controlled throttle valve (255), the electronically controlled throttle valve being arranged to control an air and fuel intake flow (210) of the internal combustion engine (110) based on a control signal from the ECU (220), wherein: The ECU (220) is arranged to increase the air and fuel intake flow (210) to above an idle flow level via the electronically controlled throttle valve (255) during start-up of the internal combustion engine (110).

52. The handheld power tool (100) according to claim 51, wherein: The electronically controlled throttle valve (255) is arranged in series with the manually controlled throttle valve (250) to control the air and fuel intake flow (210) into the internal combustion engine (110).

53. The handheld power tool (100) according to claim 52, wherein: The manually controlled throttle valve (250) includes a starting boost hole (251), which is configured to allow a starting boost air flow through the manually controlled throttle valve (250) in a closed position, wherein the ECU (220) is arranged to control the electronically controlled throttle valve (255) to increase the air and fuel intake flow (210) during the starting process of the internal combustion engine (110).

54. The handheld power tool (100) according to any one of claims 51 to 53, wherein: The manually controlled throttle valve (250) and the electronically controlled throttle valve (255) are mechanically coupled to each other (1100) such that the position of the electronically controlled throttle valve (255) at least partially determines the position of the manually controlled throttle valve (250).

55. The handheld power tool (100) according to claim 54, wherein: The mechanical connection between the manually controlled throttle valve (250) and the electronically controlled throttle valve (255) comprises cooperating cams (1110, 1120) arranged on respective valve axes (1130, 1140) of the manually controlled throttle valve (250) and the electronically controlled throttle valve (255).

56. The handheld power tool (100) according to claim 54 or 55, wherein: The mechanical linkage is arranged to bring the manually controlled throttle valve (250) into a partially open position when the electronically controlled throttle valve (255) is in a first open position (1200).

57. The handheld power tool (100) according to any one of claims 54 to 56, wherein: The mechanical linkage is arranged to bring the manually controlled throttle valve (250) into a closed position when the electronically controlled throttle valve (255) is in a second open position (1210).

58. A hand-held power tool (100) comprising a crankcase scavenged internal combustion engine (110) arranged to drive a working tool (120), in, A fuel injector (230) is configured to provide a controlled amount of fuel to an air and fuel intake flow (210) of the internal combustion engine (110), The power tool (100) comprises an electronically controlled throttle valve (255) arranged to control the air and fuel intake flow (210) based on a control signal from an ECU (220), the electronically controlled throttle valve being arranged in series with a manually controlled throttle valve (250), The fuel injector (230) is arranged downstream of the manually controlled throttle valve (250) and the electronically controlled throttle valve (255).

59. The handheld power tool (100) according to claim 58, wherein: The manually controlled throttle valve is a mechanically controlled throttle valve that operates based on the position of a trigger (145) of the handheld power tool (100).

60. The handheld power tool (100) according to claim 58, wherein: The manually controlled throttle valve is a second electronically controlled throttle valve that operates based at least in part on the position of a trigger (145).

61. The handheld power tool (100) according to any one of claims 58 to 60, wherein: The electronically controlled throttle valve (255) and the manually controlled throttle valve (250) are both arranged to control the airflow in the main combustion airflow passage (510) and the airflow in one or more gas head passages (310, 320).

62. The handheld construction device (100) according to claim 61, comprising a first partition wall (1400), wherein the first partition wall is arranged to be connected to the manually controlled throttle valve (250) and the electronically controlled throttle valve (255) to separate at least one air head passage (310, 320) is separated from the main combustion air flow channel (510).

63. The handheld power tool (100) according to any one of claims 58 to 62, wherein: The fuel injector (230) is arranged upstream of the internal combustion engine (110) and remote from the internal combustion engine (110).

64. The handheld power tool (100) according to any one of claims 58 to 63, comprising a second partition wall (350), the second partition wall being arranged to be connected to the fuel injector (230) and arranged downstream of the fuel injector, and arranged between the at least one gas head channel (310, 320) and the main combustion gas flow channel (510), wherein: The second partition wall (350) is arranged to prevent fuel from the fuel injector (230) from entering the at least one gas head passage (310, 320).

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