Compressor with directly driven variable iris diaphragm, and charging device

Abstract

The invention relates to a compressor for a charging device of an internal combustion engine and to a charging device. The compressor has an iris diaphragm mechanism which has a special drive. The drive comprises an adjustment ring as an integral component of an actuator of the drive and is designed as a rotor of an electric motor, said rotor surrounding an air supply channel. In this manner, a substantially simplified design of the drive is provided.

Description

[0001] The present invention relates to a compressor for a charging device of an internal combustion engine with a compressor wheel which is arranged in a rotationally fixed manner on a rotor shaft; an air supply duct for directing an air mass flow to the compressor wheel; an iris diaphragm mechanism arranged upstream of the compressor wheel, which has a plurality of slats adjustable via a rotatably mounted adjusting ring for closing and opening a diaphragm opening, so that a flow cross-section for the air mass flow to the compressor wheel can be variably adjusted; an actuator for rotating the adjusting ring; and a compressor housing.

[0002] Such a compressor is well known. For example, exhaust gas turbochargers in internal combustion engines have such a compressor. Its operating behavior is characterized by a so-called compressor map, which describes the pressure buildup over the throughput for various compressor speeds or peripheral speeds. The stable and usable compressor map is limited by the surge limit at low throughputs, by the stuffing limit at higher throughputs, and, structurally speaking, by the maximum speed limit. When adapting the exhaust gas turbocharger to the internal combustion engine, a compressor with the most favorable compressor map for the internal combustion engine is selected. The following requirements must be met: The engine's full-load curve must lie entirely within the usable map.

[0003] In addition, the minimum clearances from the map limits specified by the vehicle manufacturer must be maintained. Maximum compressor efficiencies must be achieved at rated load and in the range of the engine's lower torque limit. A minimum compressor moment of inertia must be maintained.

[0004] Meeting all of these requirements simultaneously with a conventional compressor without additional measures is only possible to a limited extent. The following trends, for example, are opposing: reducing the compressor's moment of inertia and maximizing the map width and peak efficiency; reducing scavenging in the lower torque range and maximizing the specific rated power and maximizing the maximum mean effective pressure of the combustion engine; improving responsiveness and increasing the specific rated power of the combustion engine.

[0005] The aforementioned conflicting objectives can be resolved by a compressor design that offers a broad characteristic map with minimal moment of inertia and maximum efficiency at the engine's full-load curve. In addition to the aforementioned steady-state requirements, stable compressor performance must also be ensured during transient operating conditions, such as rapid engine load shedding. This means that the compressor must not surge if the delivered compressor mass flow suddenly decreases.

[0006] The solutions listed above could be implemented through additional measures such as an adjustable vane guide vane, measures to reduce the compressor inlet cross-section, or a fixed recirculation channel. With variable solutions, the usable operating range of the compressor is broadened by actively shifting the characteristic map. Thus, during engine operation at low speeds and throughputs, the compressor characteristic map is shifted to the left towards lower mass flows, whereas during engine operation at high throughputs and speeds, the compressor characteristic map is not shifted or is shifted to the right. By adjusting the vane angle and inducing pre-swirl or against the compressor rotation direction, the guide vane shifts the entire compressor characteristic map towards lower or higher flow rates. The adjustment mechanism of the guide vane represents a delicate, complicated, and expensive solution.

[0007] The measures involving a narrowing of the compressor inlet by reducing the cross-section shift the compressor characteristic map toward lower flow rates by reducing the inlet cross-section by closing the structure directly in front of the compressor. When opened, the measures allow the entire inlet cross-section to be released again, thus having no or only marginal influence on the characteristic map.

[0008] The adjustment mechanisms of the variable inlet guide vane system or the cross-section-narrowing measures are usually synchronized via a link mechanism, which in turn is driven or rotated by a rotary actuator with an adjustment lever and some type of coupling rod or coupling element. Such a compressor has the features described above. The slats of the iris diaphragm mechanism are moved via the common adjustment ring. The adjustment ring has, for example, finger-like elements on its adjustment lever, into which a lever of the actuator shaft engages. The slats are rotatably and / or displaceably guided on the adjustment ring, for example by means of an actuating element. The adjustment ring has, for example, grooves for supporting / guiding the slats.

[0009] The variable iris mechanism is therefore designed to adjust the compressor's inlet mass flow. The mechanism acts as a kind of mask for the outer area of ​​the compressor inlet. With increasing throttling, i.e., cross-sectional constriction, the iris simultaneously acts as a bypass valve, preventing compressor surge. This makes it possible to actively influence the compressor's operating range and, in addition, to keep the compressor at a stable operating point in the event of a sudden engine load shedding.

[0010] When the slats of the iris diaphragm mechanism rotate parallel to the compressor's rotation axis, they pivot radially inward, resulting in the desired narrowing of the inlet cross-section directly in front of the compressor wheel. The slats are synchronized and moved via the adjustment ring. Turning the adjustment ring triggers the rotation of the slats. The operating principle is very similar to an iris diaphragm in a camera.

[0011] A compressor having the features of the preamble of claim 1 is known from EP 3 236 077 A1. Here, the slats of the iris diaphragm mechanism are moved via the common adjusting ring, which has finger-like elements on its adjusting lever, into which a lever of the actuator shaft engages.

[0012] WO 2005 / 073520 A1 describes a device for adjusting guide vanes of a gas turbine, in which the guide vanes are each pivotably connected to an adjusting ring via an adjusting lever. The adjusting lever engages with a first end on the adjusting ring and with a second end opposite the first end on an end of a shaft of the respective guide vane. A rotor of a torque motor is assigned to the adjusting ring, with a stator of the torque motor concentrically enclosing the rotor of the torque motor.

[0013] US 2017 / 0292616 A1 describes an actuating mechanism for an intake valve, wherein a rotary table actuates vanes of an actuating mechanism. The rotary table is actuated by an actuator. It has a pawl by which the rotary table is rotated.

[0014] The present invention is based on the object of providing a compressor of the type described above, which is characterized by a particularly simple structure.

[0015] This object is achieved according to the invention in a compressor of the type specified by the characterizing features of patent claim 1.

[0016] The solution according to the invention is characterized in that the adjusting ring is no longer controlled and moved via a separate actuator, but forms an integral part of the actuator. Rather, the adjusting ring simultaneously forms the rotor of an electric motor, so that when the electric motor is supplied with appropriate current, the adjusting ring is moved in one direction or the other, whereby the slats are moved to open or close the iris diaphragm mechanism, i.e. pivoted outwards or inwards, and thus lead to the desired widening or narrowing of the inlet cross-section of the air supply duct. The corresponding torque transmission from the adjusting ring to the slats can be realized with the help of actuating sections or actuating elements, which are mounted or guided, for example, in grooves in the adjusting ring.

[0017] The adjustment ring, the iris diaphragm mechanism, and the compressor wheel are arranged one after the other in the direction of flow of the air supply duct. The inflow duct therefore opens directly onto the adjustment ring.

[0018] The direct drive designed according to the invention offers a number of advantages. It combines previously separate functions into a single component. This results in a high degree of integration with fewer components and a smaller installation space requirement. This results in less wear and improved durability of the entire mechanism.

[0019] By eliminating the coupling elements in the current technology, friction is reduced. The electric motor results in favorable response and adjustment speed with improved positioning and lower hysteresis. Overall, costs are lower, and rattling noises caused by vibrations can be avoided when mounted on a turbocharger compressor on the engine.

[0020] During operation, the airflow is directed through the adjusting ring via the aperture mechanism to the compressor wheel. The airflow thus also advantageously serves to cool the electric motor rotor, which acts as the adjusting ring.

[0021] In the solution according to the invention, the adjusting ring is preferably designed as the rotor of a torque motor. Such torque motors are known. This is a multi-pole electric direct drive that can transmit very high torques at relatively low speeds. For example, a permanently excited brushless DC motor is used, which is preferably designed as an internal rotor (stator on the outside, rotor on the inside). The adjusting ring forms the rotor of the internal rotor.

[0022] Such a torque motor is particularly well-suited for implementing the corresponding rotary movements of the adjustment ring for pivoting the slats. By applying different currents to the torque motor, the adjustment ring is rotated clockwise or counterclockwise.

[0023] In a specific embodiment, the adjusting ring has a plurality of permanent magnets arranged around its circumference. Preferably, a plurality of coils of the electric motor are positioned on the inside of the compressor housing around its circumference. These coils can also be arranged on the inside of a special housing of the diaphragm mechanism or on the inside of any other fixed component.

[0024] For this reason, magnets are specifically arranged on the adjusting ring or rotor, mounted at a distance around the circumference of the rotor. These magnets interact with the coils arranged at a distance on the inside of the compressor housing or orifice housing. By applying different currents to the coils, a specific adjusting ring position is achieved, which represents a balance between the magnetic forces of attraction and repulsion.

[0025] Magnets can be distributed over the entire circumference of the rotor and coils over the entire circumference of the housing or only over part of the circumference.

[0026] The rotor of the electric motor, designed as an adjusting ring, can be configured to synchronously drive each blade of the iris diaphragm mechanism. This can be achieved, for example, by having each blade with an actuating element that engages a groove in the adjusting ring to guide the respective blade. However, an embodiment can also be designed such that the adjusting ring directly drives only one main blade of the iris diaphragm mechanism, while the other blades are driven via the adjacent blade.

[0027] The present invention further relates to a charging device for an internal combustion engine with a compressor of the type described above.

[0028] The invention is explained in detail below using an exemplary embodiment in conjunction with the drawing. In the drawings: Figure 1 is a schematic diagram from the front of the main components of a direct drive for an iris diaphragm mechanism of a compressor; and Figure 2 is a schematic diagram from the side of the direct drive of the Figure 1 ; and Figure 3 a partial sectional view of a compressor.

[0029] The exemplary embodiment shown here relates to a compressor for a supercharging device for an internal combustion engine, which is provided with a compressor wheel 7 that is arranged non-rotatably on a rotor shaft (not shown). The compressor wheel 7 receives air flow via an air supply duct 6. Upstream of the compressor wheel 7 is an iris diaphragm mechanism 3 (shown only schematically), which has a plurality of adjustable or pivotable slats 8 for closing and opening the diaphragm opening in the iris diaphragm mechanism, so that a flow cross-section for the air mass flow flowing towards the compressor wheel 7 can be adjusted. In the exemplary embodiment shown here, the iris diaphragm mechanism 3 has three slats 8 that set a corresponding diaphragm opening 9.

[0030] An adjustment ring 2 is used to adjust the individual slats 8. The adjustment ring 2 is rotated, pivoting the slats 8 inward or outward to adjust the aperture. For this purpose, each slat is provided with an actuating element that is guided in a corresponding groove (not shown) of the adjustment ring.

[0031] Permanent magnets 5 are arranged at intervals around the circumference of the adjusting ring 2. Coils 4 are arranged at intervals along the inside of the circumference of the compressor housing 1. The compressor housing 1 with the coils 4 forms the stator, and the adjusting ring 2 with the magnets 5 forms the rotor of a torque motor. By applying different currents to the coils 4, the adjusting ring 2 is rotated, thereby causing the slats to pivot inward or outward to adjust the aperture 9.

[0032] How to Figure 2As can be seen, the aperture mechanism 3 is located directly upstream of the compressor wheel 7 and the adjusting ring 2 is located directly upstream of the aperture mechanism 3. The adjusting ring 2 surrounds the inflow channel 6, so that during operation the air flow is directed through the adjusting ring 2 via the aperture mechanism 3 onto the compressor wheel 7. The air flow thus also serves to cool the rotor acting as the adjusting ring 2.

[0033] The adjusting ring 2 is therefore integrated into the actuator for the iris diaphragm mechanism and represents the rotor of a torque motor. The number of magnets 5 and coils 4 shown in the figures is merely exemplary. Depending on the current supply to the coils 4, the adjusting ring 2 is Figure 1 turned left or right to open or close the aperture mechanism.

[0034] Figure 3shows a partial sectional view of a compressor equipped with an iris diaphragm mechanism 3. A compressor wheel 7 is exposed to air flow via an air supply duct 6. An iris diaphragm mechanism 3 is used to adjust the flow cross-section.

[0035] The iris diaphragm mechanism 3 has an adjusting ring 2, around the circumference of which permanent magnets 5 are arranged. Coils 4 are provided adjacent to this in the compressor housing 1. By energizing the coils 4, the adjusting ring 2 is rotated, thereby opening or closing the iris diaphragm mechanism 3.

Claims

1. Compressor for a supercharging device of an internal combustion engine, having a compressor wheel (7) which is arranged rotationally conjointly on a rotor shaft; an air supply channel (6) for conducting an air mass flow to the compressor wheel (7); an iris diaphragm mechanism (3) which is arranged upstream of the compressor wheel (7) and which has multiple lamellae (8), adjustable by means of a rotatably mounted adjusting ring (2), for closing and opening a diaphragm opening, such that variable setting of a flow cross section for the air mass flow for incident flow on the compressor wheel (7) is possible; an actuator for rotating the adjusting ring (2); and a compressor housing (1); wherein the adjusting ring (2), the iris diaphragm mechanism (3) and the compressor wheel (7) are arranged successively in the flow direction of the air supply channel (6), characterized in that the adjusting ring (2) forms an integral component of the actuator and is formed as the rotor of an electric motor surrounding the air supply channel (6), which surrounds the air supply channel (6) in such a manner that the air flow conducted through the air supply channel (6) cools the rotor of the electric motor acting as an adjusting ring (2).

2. Compressor according to Claim 1, characterized in that the adjusting ring (2) is formed as the rotor of a torque motor.

3. Compressor according to Claim 1 or 2, characterized in that the adjusting ring (2) has a multiplicity of permanent magnets (5) arranged around its circumference.

4. Compressor according to one of the preceding claims, characterized in that a multiplicity of coils (4) of the electric motor are positioned on the inside of the compressor housing (1) around the circumference thereof.

5. Compressor according to one of the preceding claims, characterized in that the adjusting ring (2) drives each lamella (8) of the iris diaphragm mechanism (3) synchronously.

6. Compressor according to one of Claims 1 to 4, characterized in that the adjusting ring (2) directly drives only a main lamella of the iris diaphragm mechanism (3).

7. Supercharging device for an internal combustion engine, having a compressor according to one of the preceding claims.

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