Engine with combustion unit and compressed air unit

Abstract

Engine comprehensive: - a combustion unit (01) with a combustion cylinder (02), a combustion piston (03) which is axially movable therein and to which a connecting rod (05) is coupled in order to transmit the force supplied by the combustion piston (03) to a crankshaft (06); - a compressed air unit (10) with a pressure cylinder (11) which has a compressed air outlet (12) and in which an axially movable pressure piston (13) is arranged, wherein the pressure piston (13) is coupled to the combustion piston (03) via a push rod (40) so that the pressure piston (13) carries out a stroke movement which is functionally reciprocal to the combustion piston (03) in order to expel compressed air from the compressed air outlet (12) in a compression stroke when the combustion piston (03) carries out an expansion stroke in the combustion cylinder (02) due to a combustion explosion; - a compressed air motor unit (30) with a rotor (31) which is rotatable about a rotor axis (33) in a rotor housing (32), wherein numerous pressure chambers (34) are formed on the outer circumference of the rotor (31), each having at least one impact surface (35), wherein the compressed air outlet (12) of the compressed air unit (01) opens into the rotor housing (32) of the compressed air motor unit (30) so that the compressed air emerging at the compressed air outlet (12) strikes the impact surfaces (35) of the pressure chambers (34) in order to set the rotor (31) in rotation.

Description

[0001] The present invention relates to an engine with a combustion unit and a compressed air unit. Such an engine is characterized, among other things, by the fact that it delivers increased torque compared to conventional combustion engines without significantly increasing fuel consumption.

[0002] A wide variety of engine designs are known for propulsion purposes and for the general provision of energy. For example, internal combustion engines, which generate energy from the combustion of a liquid or gaseous fuel, have been predominantly used in vehicles for decades. Electric motors, which obtain energy from electrical current supplied to the motor by a public grid or a generator, are used in a wide variety of machines, but increasingly also in vehicles. In addition, there are numerous special types of engines, the design of which is determined both by their intended use and by the energy used.

[0003] Internal combustion engines continue to offer numerous advantages, particularly when powered by synthetic fuels that can be generated using renewable energy. However, conventional internal combustion engines have the disadvantage, among other things, of limited torque per cylinder. This is also due to the fact that the leverage ratios during the typical conversion of the translational movement of a piston moving alternately in the cylinder into a rotational movement of the crankshaft at the moment of explosion of a combustion mixture in the cylinder are unfavorable. Therefore, particularly in so-called short-stroke engines, which have only a short piston stroke, high torques cannot be achieved.

[0004] Air motors, also known as pneumatic motors, are known for converting the energy from compressed air (or a similar gas) into mechanical work. Conventional air motors are supplied with compressed air, stored in a tank, for example. The compressed air is fed into the motor through an inlet valve and flows into a cylinder. The compressed air expands in the cylinder and presses on a piston, causing it to move linearly or, in the case of a rotary piston, rotate. Once the air has performed its mechanical work, it is released from the cylinder through a release valve. This process is repeated continuously as long as the motor is supplied with compressed air. Air motors are preferred for use in industrial applications because they are robust, reliable, and easy to maintain.They can also be used in potentially explosive environments, as there is no combustion process and, due to the lack of electrical components, there is no risk of sparking.

[0005] DE 38 28 897 C1 describes a rotary piston air motor with a rotor arranged inside a housing, which is connected to a drive shaft extending from the housing. Furthermore, this air motor has a compressed air supply line connected to the housing and an exhaust air line connected to the housing. The housing is flameproof and hermetically sealed to provide explosion protection. An ignition barrier is installed in both the compressed air supply line and the exhaust air line. A safety valve is also installed in the exhaust air line and / or the compressed air supply line.

[0006] DE 25 08 693 A1 describes a rotating compressed air motor, which can be designed, in particular, as a vane-type motor and is preferably used in power tools. This rotating compressed air motor has a housing and a compressed air inlet arranged therein. Furthermore, a speed controller is provided, which has a number of loose balls as centrifugal weights. These balls are guided in a chamber that is axially fixed and non-rotatably connected to the motor rotor, between an axially immovable end wall of the chamber and an end wall that is axially displaceable against the resistance of a resilient component.

[0007] DE 1 706 447 U describes an air motor configured as a rotary piston machine with a multi-cell design. Diametrically opposed, sickle-shaped working chambers are arranged on both sides of a rotor, so that the rotor is centrally located in the housing. The housing features sliding surfaces, machined to the radius of the rotor, arranged between the respective ends of the working chambers, which serve to separate these chambers from each other.

[0008] Previously known compressed air motors require a continuous supply of compressed air to operate. Therefore, compressed air motors are not particularly suitable for mobile use in motor vehicles, as providing the required compressed air is difficult. However, there are technical concepts in which the used air is recompressed after use in the motor so that it can be reused. These closed systems are complex and require additional components such as compressors and energy storage devices to compress the air back to the desired pressure. In a closed system without a supply of new compressed air or recompression, there is a risk of pressure drop, meaning the motor stops as soon as the pressure drops.

[0009] An object of the present invention, based on the prior art, is to provide an improved engine which retains the advantages of conventional internal combustion engines and yet provides significantly increased torque.

[0010] This object is achieved by a motor according to the appended claim 1. The subclaims name preferred embodiments.

[0011] Firstly, the invention is based on the assumption that the torque provided by an internal combustion engine is limited, among other things, by the piston stroke and the gear ratio to the crankshaft. In an internal combustion engine designed as a reciprocating piston engine, whose axially movable piston is coupled to a crankshaft via a connecting rod, the length of the axial piston stroke also limits the effective lever length on the crankshaft (corresponds to the crank radius) to which the connecting rod is pivoted. This essentially determines the torque that can be tapped. So-called short-stroke engines, whose stroke is, for example, 50 mm or less, can only generate a comparatively small torque. So-called long-stroke engines, whose stroke can be, for example, more than 60 mm, can generate greater torque, but require more installation space and can only be operated at lower speeds.Instead, the invention provides a motor that can provide significantly increased torque despite a small stroke.

[0012] The engine according to the invention initially has a combustion unit, which is preferably designed as a reciprocating piston engine in a conventional manner. For this purpose, the combustion unit has, in a conventional manner, a combustion cylinder and a combustion piston that is axially movable within the combustion cylinder. The combustion unit preferably has further elements that enable its typical operation, in particular injection units, cooling and lubrication channels, etc., which, however, are not important with regard to the present invention and can be suitably selected by a person skilled in the art. The combustion piston is coupled to a connecting rod in order to transfer the force (kinetic energy) supplied by the combustion piston during a combustion process (explosive combustion of the fuel in the cylinder) to a crankshaft and set it in rotation. A downstream machine unit can then be driven by the crankshaft.

[0013] The engine according to the invention further comprises a compressed air unit with a pressure cylinder having a compressed air outlet. A pressure piston, which is also axially movable, is arranged in the pressure cylinder. The pressure piston is coupled to the combustion piston via a push rod, so that the pressure piston follows the stroke movement of the combustion piston with a reciprocal function. This means that the pressure piston performs a compression stroke to expel compressed air from the compressed air outlet when the combustion piston performs an expansion stroke in the combustion cylinder due to a combustion explosion.

[0014] In a preferred embodiment, the combustion cylinder and the pressure cylinder are aligned on a common central axis, so that the combustion piston and the pressure piston also move in the same direction along this common central axis. If, in this embodiment, the combustion cylinder and the pressure cylinder are opposite each other with their open end faces, this leads to a stroke movement of the two pistons that is in the same direction with regard to the direction of movement, but reciprocal with regard to the function, i.e. when the combustion piston performs a compression stroke, the pressure piston moves in the expansion stroke and vice versa. In this embodiment, the two pistons can be rigidly connected to one another via a rigid push rod system, preferably comprising at least two rods running parallel to the axis, so that the push rod system only allows a single degree of freedom.

[0015] However, other embodiments are also possible in which the push rod provides a further degree of freedom, in particular to compensate for bearing play and prevent jamming of the pistons, or to enable the two pistons to be arranged with an offset axis. Likewise, the two cylinders could be arranged parallel to one another and have the same orientation; in this case, the push rod could be designed, for example, in the manner of a rocker, to enable the functionally reciprocal stroke movement between the two pistons.

[0016] Finally, the motor has a pneumatic motor unit with a rotor that can rotate around a rotor axis in a rotor housing. Numerous pressure chambers are formed on the outer circumference of the rotor, each having at least one impact surface. The compressed air outlet of the pneumatic unit opens into the rotor housing of the pneumatic motor unit, so that the compressed air exiting the compressed air outlet impacts the impact surfaces of the pressure chambers to set the rotor in rotation. The pressure chambers are preferably arranged around the entire circumference of the rotor.

[0017] This results in the following general functioning of the engine according to the invention: During the power stroke of the combustion unit, fuel is burned in the combustion cylinder. The explosive combustion drives the combustion piston out of the combustion cylinder during the expansion stroke. The push rod transmits this movement to the pressure piston, which then performs a compression stroke in the pressure cylinder. This compresses air in the pressure cylinder and forces it out of the compressed air outlet at high pressure. This compressed air is guided to the impact surfaces of the rotor of the compressed air motor unit, causing the rotor to rotate. As usual, torque can be tapped at the crankshaft of the combustion unit. Additional torque is available at the rotor axis of the compressed air motor unit. Both torques are preferably combined and increase the total torque provided by the engine.

[0018] According to a preferred embodiment, the rotor axis of the compressed air motor unit is coupled to the crankshaft of the combustion unit in such a way that the torques available at the rotor axis and the crankshaft are mechanically added. This is particularly preferably achieved by coupling the rotor axis to a crank, which is coupled to the crankshaft of the combustion unit via a coupling rod. In this case, the rotational speed of the rotor axis and the crankshaft of the combustion unit are identical. In modified embodiments, however, gear elements can also be interposed to enable different rotational speeds.

[0019] Preferably, the pressure cylinder has at least one check valve, which allows ambient air to flow into the pressure cylinder during the expansion stroke of the pressure piston. In this embodiment, the air required in the subsequent compression stroke does not have to flow through the rotor of the pneumatic motor unit, thereby increasing the rotation speed and thus the efficiency. In an advantageous embodiment, the pressure cylinder has several check valves, for example four or six, distributed around the circumference of the pressure cylinder.

[0020] In preferred embodiments, the combustion unit is designed as a 4-stroke engine or a 2-stroke engine. It is particularly preferred if the combustion unit is designed as a 4-stroke engine and a controlled bypass valve is arranged at the pressure outlet of the pressure cylinder. This bypass valve opens when the pressure piston of the compressed air motor unit performs a compression stroke and the combustion piston simultaneously performs an expansion stroke to draw in fuel or a fuel-air mixture (intake stroke). Without the bypass valve, the pressure piston would have to work against the volume in the pressure cylinder even during the intake stroke, which would unnecessarily consume energy.

[0021] According to a special embodiment, the bypass valve has a control disc that is controlled by drivers attached to the rotor of the compressed air motor unit. Through coordinated positioning of the drivers, the bypass valve is always opened at the correct time, namely when air is to escape from the pressure cylinder, without a power stroke being performed in the combustion unit (after the fuel has been burned), but rather when new fuel is being supplied (intake stroke). In this embodiment, the bypass valve can have a freewheel lock that prevents the control disc from continuing to rotate unintentionally. The freewheel lock can be implemented, for example, using one or more permanent magnets.

[0022] In a modified embodiment, the bypass valve is designed as an electromagnetic valve and is controlled by an electronic control unit.

[0023] It is advantageous if the pressure cylinder of the compressed air unit is formed integrally with the rotor housing of the compressed air motor unit. In particular, it is advantageous if the pressure cylinder of the compressed air unit and the rotor housing of the compressed air motor unit are manufactured together as a die-cast aluminum part. Other embodiments remain possible.

[0024] Further details and advantages of the invention will become apparent from the following description of preferred embodiments, with reference to the drawings. Fig. 1 is a highly simplified representation of a first embodiment of an engine according to the invention with a check valve; Fig. 2 a highly simplified representation of a second embodiment of the engine with a bypass valve.

[0025] Fig. 1 shows a highly simplified representation of an engine according to the invention in a first embodiment. The engine has a combustion unit 01 with a combustion cylinder 02 and a combustion piston 03 that is axially movable or operates translationally therein and alternately performs a compression stroke, in which the volume between the combustion piston and the combustion cylinder is reduced, and an expansion stroke, in which this volume is increased. Fuel is supplied to the combustion cylinder and exhaust gases are discharged via an inlet / outlet 04. The inlet and outlet 04 can be designed as multiple channels and equipped with valves (not shown). A connecting rod 05 is coupled to the combustion piston 03. The translationally acting force supplied by the combustion piston 03 during the power stroke is transmitted via the connecting rod 05 to a crankshaft 06 and thus transformed into torque.

[0026] A compressed air unit 10 has a pressure cylinder 11 with a compressed air outlet 12. The compressed air outlet 12 is opposite the force surface of an axially movable or translationally operating pressure piston 13, which moves alternately within the pressure cylinder 11. The pressure piston 13 is coupled to the combustion piston 03 via a push rod 14, so that in the example shown, the pressure piston 13 performs a translational movement in the same direction as the combustion piston 03. Since the combustion cylinder 02 and the pressure cylinder 11 are opposite one another in terms of their compression chamber, the combustion piston 03 and the pressure piston 13 perform functionally reciprocal stroke movements, so that the pressure piston 13 expels compressed air from the compressed air outlet 12 during a compression stroke when the combustion piston 03 performs an expansion stroke in the combustion cylinder 02 due to a combustion explosion.

[0027] A compressed air motor unit 30, which also belongs to the motor according to the invention, has a rotor 31 which is rotatable about a rotor axis 33 in a rotor housing 32, wherein numerous pressure chambers 34 are formed on the outer circumference of the rotor 31, each having at least one impact surface 35. The compressed air outlet 12 of the compressed air unit 10 opens into the rotor housing 32 of the compressed air motor unit 30 such that the compressed air exiting the compressed air outlet 12 impinges on the impact surfaces 35 of the pressure chambers 34 to set the rotor 31 in rotation.

[0028] At the pressure-side end of the pressure cylinder 11 there is Fig. 1, a check valve 14. In the open state, this valve allows air to flow largely unhindered into the pressure cylinder 11 when the pressure piston 13 performs an expansion movement, i.e., when the combustion piston 03 performs a compression movement. If the pressure piston 13 instead moves in a compression movement, the check valve 14 closes, so that the compressed air does not escape from the valve, but is conveyed through the compressed air outlet 12 to the compressed air motor unit 30.

[0029] One in Fig. 1 only indicated coupling rod 40 couples the crankshaft 06 of the combustion unit 01 with the rotor axis 33 of the compressed air motor unit 30, so that these two elements rotate in the same direction and the tappable torques add up.

[0030] Fig. 2 shows a highly simplified representation of a second embodiment of the motor, which in its basic structure is initially similar to the previously described embodiment.

[0031] Easier to recognize is Fig. 2 the coupling rod 40, which extends between the crankshaft 06 and the rotor axis 33. The check valve in the pressure cylinder 11 is not explicitly provided in this embodiment, although it may be present.

[0032] Additionally present in the embodiment according to Fig.2 a bypass valve 15, which is designed in the manner of a control disk and carries several pins 16. The pins 16 interact with drivers (not shown) that are attached to the rotor 31 in order to act in a controlling manner on the bypass valve 15 in predetermined angular positions and to open or close it. The bypass valve 15 is open when - in the case of a combustion unit 01 operating according to the 4-stroke principle - the combustion piston 03 sucks in fuel, i.e. performs an expansion stroke, and the pressure piston 13 performs a compression stroke. Since the combustion unit 01 cannot provide any power during this stroke, the compression of the air in the pressure cylinder 11 would be a hindrance, so that the air can escape through the bypass valve 15. In the working stroke of the combustion piston 03, however, a large force is available, so that the bypass valve 15 remains closed, the air in the pressure cylinder 11 is compressed and can thus drive the rotor 31.

[0033] In modified embodiments, the engine described may comprise a plurality of combustion units, a plurality of compressed air units and a plurality of compressed air motor units combined to form a common machine. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 38 28 897 C1

[0005] DE 25 08 693 A1

[0006] DE 1 706 447 U

[0007]

Claims

[1] Engine comprising: - a combustion unit (01) with a combustion cylinder (02), a combustion piston (03) which is axially movable therein and to which a connecting rod (05) is coupled in order to transmit the force supplied by the combustion piston (03) to a crankshaft (06); - a compressed air unit (10) with a pressure cylinder (11) which has a compressed air outlet (12) and in which an axially movable pressure piston (13) is arranged, wherein the pressure piston (13) is coupled to the combustion piston (03) via a push rod (40) so that the pressure piston (13) carries out a stroke movement which is functionally reciprocal to the combustion piston (03) in order to expel compressed air from the compressed air outlet (12) in a compression stroke when the combustion piston (03) carries out an expansion stroke in the combustion cylinder (02) due to a combustion explosion; - a compressed air motor unit (30) with a rotor (31) which is rotatable about a rotor axis (33) in a rotor housing (32), wherein numerous pressure chambers (34) are formed on the outer circumference of the rotor (31), each having at least one impact surface (35), wherein the compressed air outlet (12) of the compressed air unit (01) opens into the rotor housing (32) of the compressed air motor unit (30) so that the compressed air emerging at the compressed air outlet (12) strikes the impact surfaces (35) of the pressure chambers (34) in order to set the rotor (31) in rotation. [2] Engine according to claim 1, characterized by that the combustion unit (01) is designed as a reciprocating piston engine. [3] Engine according to claim 1 or 2, characterized by that the rotor axis (33) of the compressed air motor unit (30) is coupled to the crankshaft (06) of the combustion unit (01), so that the torques that can be tapped off at the rotor axis (33) and the crankshaft (06) are added. [4] Engine according to claim 3, characterized by that the rotor axis (33) is coupled to a crank which is coupled to the crankshaft (06) of the combustion unit (01) via a coupling rod (40). [5] Engine according to one of claims 1 to 4, characterized by that the pressure cylinder (11) has at least one check valve (14) which allows air to flow into the pressure cylinder (11) during the expansion stroke of the pressure piston (13). [6] Engine according to claim 5, characterized by that the pressure cylinder (11) has a plurality of check valves (14) which are arranged distributed around the circumference of the pressure cylinder (11). [7] Engine according to one of claims 1 to 6, characterized by that the combustion unit (01) is designed as a 4-stroke engine or as a 2-stroke engine. [8] Engine according to claim 7, characterized bythat the combustion unit (01) is designed as a 4-stroke engine and that a controlled bypass valve (15) is arranged at the pressure outlet (12) of the pressure cylinder (11), which opens when the pressure piston (13) performs a compression stroke and the combustion piston (03) performs an expansion stroke to suck in fuel. [9] Engine according to claim 8, characterized by that the bypass valve (15) comprises a control disc which is controlled by drivers attached to the rotor (31) of the compressed air motor unit (30). [10] Engine according to claim 8, characterized by that the bypass valve is designed as an electromagnetic valve. [11] Engine according to one of claims 1 to 10, characterized by that the pressure cylinder (11) of the compressed air unit (10) is formed integrally with the rotor housing (32) of the compressed air motor unit (30). [12] Engine according to claim 11, characterized bythat the pressure cylinder (11) of the compressed air unit (10) and the rotor housing (32) of the compressed air motor unit (30) are manufactured together as an aluminum die-cast part. [13] Engine according to one of claims 1 to 12, characterized by that the combustion piston (03) and the pressure piston (13) are aligned along a common central axis and carry out their respective stroke movements along this central axis.

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