CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and all the benefits of U.S. Provisional Application No. 61/908,239, filed on November 25, 2013, and entitled "Two Piece Compressor Housing," which is incorporated herein by reference.

BACKGROUND

Field of the Disclosure

This disclosure relates to cast compressor covers. More particularly, this disclosure relates to a compressor and method of forming a shaped volute of the compressor using a reusable mold process.

Description of Related Art

A turbocharger is a type of forced induction system used with internal combustion engines. Turbochargers deliver compressed air to an engine intake, allowing more fuel to be combusted, thus boosting the horsepower of the engine without significantly increasing engine weight. Turbochargers allow for the use of smaller engines having the same amount of horsepower as larger, normally aspirated engines. The use of a smaller engine in a vehicle decreases the mass of the vehicle, increases performance, and enhances fuel economy. Moreover, turbochargers provide a more complete combustion of the fuel delivered to the engine, which contributes to the highly desirable goal of a cleaner environment.

Turbochargers typically include a turbine housing connected to the exhaust manifold of the engine, a compressor housing connected to the intake manifold of the engine, and a center bearing housing coupled between the turbine and compressor housings. A turbine wheel in the turbine housing is rotatably driven by an inflow of exhaust gas supplied from the exhaust manifold. A shaft rotatably supported in the center bearing housing connects the turbine wheel to a compressor impeller in the compressor housing so that rotation of the turbine wheel causes rotation of the compressor impeller. The shaft connecting the turbine wheel and the compressor impeller defines an axis of rotation. As the compressor impeller rotates, it increases the air mass flow rate, airflow density and air pressure delivered to cylinders of the engine via the intake manifold.

A turbocharger compressor generally consists of three essential components, the compressor housing, a compressor wheel disposed in the compressor housing, and a diffuser. The compressor housing includes an outer portion having an outer wall that forms the compressor volute and a backplate. As the compressor wheel rotates, air is drawn in axially, accelerated to a much higher velocity and then expelled in a radial direction into the diffuser. The diffuser slows down the air and allows the air pressure and temperature to rise. Typically, the diffuser is formed by the compressor backplate and a portion of the volute, and serves to collect the air and to further decrease the velocity of the air flow prior to exiting the compressor.

Some conventional compressor volute shapes, in particular "closed" volute designs, require that the compressor housing is formed using sand cast technologies and prevent the use of a reusable mold. "Closed" compressor volute designs include an outer cover which contains an outer volute portion, an insert or diffuser portion which forms an inner volute portion and a backplate. The backplate can be either a straight/standard backplate or a backplate that incorporates a portion of the curved volute shape. The outer volute portion, insert/diffuser and backplate together form the inner/curved shape of the "closed" volute design. Flow in a "closed" compressor volute is spun gradually about the inner/curved shape of the volute. However, the flow in a standard or "open" compressor volute is directed into a sharp corner formed by a portion of the compressor volute and the straight/standard backplate and stagnates against a wall formed therebetween, rather than being turned by the curved shape of the volute, and ultimately wastes energy and decreases the turbocharger efficiency. Reusable mold techniques, such as die casting and injection molding are advantageous processes used especially with large volume productions. Die casting and injection molding are manufacturing processes that allow for the repeat use of mold parts as well as which incorporates an inherent ability to create superior shapes having detailed characteristics and is a less expensive process than alternative processes. Therefore, it is desirable to create a volute design that performs similarly to that of a "closed" shaped volute but wherein the compressor housing incorporating an intricate curved volute shape can be formed using a reuasable mold process.

SUMMARY

This disclosure details the use of a compressor housing that is formed using a reusable mold technique wherein the compressor housing includes a two-piece structure including of a compressor cover portion and a compressor backplate. The compressor cover portion of the compressor housing is very much similar to a conventional compressor outer housing portion having a standard or "open" volute shaped design. In this instance; however, half of the compressor volute shape is formed in the compressor cover and the other half of the compressor volute shape is formed by the compressor backplate. The compressor cover and backplate, together, act to mimic the flow demonstrated by "closed" volute designs where the air flow is guided through the diffuser and into the curved shape of the volute. The compressor housing and method disclosed herein eliminates the need for a diffuser/insert and/or core element typically used in the manufacturing process because portions of the "open" volute shaped compressor cover and the backplate act to form the "diffuser" portion of the compressor thereby reducing flow losses, improving stage performance, allowing for an ease of manufacture and assembly and decreasing overall production costs.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the disclosure will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Figure 1 is a perspective view of the compressor.

Figure 2 is a cross-sectional view of the two-piece compressor housing.

Figure 3A is perspective view of the cover of the two-piece compressor housing.

Figure 3B is perspective view of the backplate of the two-piece compressor housing.

Figure 4 is a cross-sectional view of a die cast/injection mold apparatus including the inventive mold.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring to Figs. 1-3, according to one aspect of the disclosure, a compressor (10) is provided for increasing the mass flow intake of air entering the turbocharger (not shown). The compressor (10) consists of a two-piece housing (12) comprising a cover (14) and a backplate

(16). The cover (14) mimics the conventional "open" volute design wherein the cover (14) includes a first diffuser face (18) that extends into a transverse wall (20), an upper curved portion

(22a), and ends in an opposing wall (24). The opposing wall (24) further includes a first stepped portion (24a) and a second stepped portion (24b). The backplate (16) includes a second diffuser face (26) that continues into a lower curved portion (22b). An outer wall (28) of the backplate

(16) further includes a shaped area (28a) formed at one end thereof and an end wall (28b) formed at an opposing end thereof. The shaped area (28a) conforms to and engages the second stepped portion (24b) of the opposing wall (24) of the cover (14) and the end wall (28b) conforms to and engages the first stepped portion (24a) of the opposing wall (24) of the cover (14). The first and second stepped portions (24a, 24b) formed in the opposing wall (24) of the cover (14) mate with the end wall (28b) of the backplate (16) and the shaped area (28a) of the outer wall (28) of the backplate (16); respectively, to form the compressor volute (22) and space the backplate (16) from the cover (14) such that the first diffuser face (18) of the compressor cover (14) and the second diffuser face (26) of the backplate (16) form the compressor diffuser (30). Engagement of the end (28b) of the backplate (16) with the first stepped portion (24a) of the cover (14) allows the lower curved portion (22b) of the backplate (16) to mate with the upper curved portion (22a) of the cover (14) and transform the "open" volute shape design of the cover (14) into a smooth flowing "closed" volute shape design (22). Both the cover (14) and the backplate (16) can each include a half tongue portion (62a, 62b) such that when the cover (14) and backplate are joined together to form the compressor housing (12), a full compressor tongue is formed (not shown) and allows the flow of air to be guided properly, thereby increasing flow capacity. The cover (14) and backplate (16) are held together by conventional fixing/connecting methods and devices such as screws, etc. The combination of the cover (14) and backplate (16) to form the compressor housing (12) improves aerodynamic performance and increases efficiency.

According to another aspect of the disclosure, a reusable mold device (40) for forming a compressor housing (12) is provided. The reusable mold device (40) is used in a reusable mold process, disclosed in detail below, such as a die casting or injection molding. The reusable mold device (40) consists of a two-piece mold used to form the compressor (10). The two piece mold comprises a compressor cover portion (42a) and a backplate portion (42b). The compressor cover portion (42a) comprises a first volute portion (not shown) formed therein. The first volute portion includes a first diffuser face forming portion (not shown), a transverse wall forming portion (not shown), an upper curve forming portion (not shown), and an opposing wall forming portion (not shown). The opposing wall forming portion further includes a first step forming portion (not shown) and a second step forming portion (not shown). The first diffuser face forming portion, transverse wall forming portion, upper curve forming portion, opposing wall forming portion, and first and second step forming portions correspond; respectively, to form the first diffuser face (18), transverse wall (20), upper curved portion (22a), outer wall (24), and first and second stepped portions (24a, 24b) of the cover (14).

The backplate portion (42b) comprises a second volute portion (not shown) formed therein. The second volute portion includes a second diffuser face forming portion (not shown), a lower curve forming portion (not shown), and an outer wall forming portion (not shown). The outer wall forming portion further includes a shaped area forming portion (not shown) and an end wall forming portion (not shown). The second diffuser face forming portion, lower curve forming portion, outer wall forming portion, shaped area forming portion, and end wall forming portion correspond; respectively, to form the second diffuser face (26), lower curved portion (22b), outer wall (28), shaped area (28a), and end wall (28b)of the backplate (16). The first volute portion of the reusable mold device (40) represents one half of the compressor volute (22), while the second volute portion of the reusable mold device (40) represents the second half of the compressor volute (22). The compressor cover portion (42a) and a backplate portion (42b) of the reusable mold device (40) may further include half tongue contour forming portions (not shown); respectively, and are used to form the tongue (32) of the compressor (10). While the two-piece mold consists of the compressor cover portion and backplate portion, the compressor cover (14) and backplate (16) may be formed either separately or together using the two-piece reusable mold and process detailed below.

Referring to Fig. 4, according to yet another aspect of the disclosure, a method of forming the compressor housing (12) using the two-piece reusable mold device (40), detailed above, is provided. As mentioned, the compressor cover (14) and backplate (16) may be formed either separately or together using the two-piece reusable mold device (40) in a die cast or an injection molding process. When the compressor cover (14) and backplate (16) are formed separately, the compressor cover portion (42a) and backplate portion (42b) of the reusable two-piece mold are each joined with a second/opposing mold member (44) and placed individually in a die cast or injection mold assembly similar to that detailed in Figure 4, and secured by ejector pins/bolts 46, etc.. Once placed in the die cast or injection mold assembly, material M such as plastic or metal, etc. is poured into the die cast or injection mold assembly and delivered to the compressor cover portion (42a) or the backplate portion (42b) where the conventional die cast or injection mold process is carried out accordingly. When the compressor cover (14) and backplate (16) are formed together using the die cast or injection mold assembly, both the compressor cover portion (42a) and the backplate portion (42b) of the reusable two-piece mold are each joined with a second/opposing mold member (44) and placed together in a die cast or injection mold assembly, also similar to that detailed in Figure 4, and secured by ejector pins/bolts (46), etc.. In this instance, standard plates (not shown) are inserted between the compressor cover portion (42a) and the backplate portion (42b), and the die cast or injection mold assembly is filled with material M such as plastic or metal, etc. and delivered to the compressor cover portion (42a) or the backplate portion (42b) where the conventional die cast or injection mold process is also carried out accordingly. Compressor (10) includes an outlet (64), shown in figure 3 A, but not described in detail. The outlet (64) is a conventional compressor outlet, but requires special attention when forming compressor housing (12) using either the die cast or injection mold processes. In this regard, a separate pull tool (not shown), that conforms to the shape of the inner diameter of the outlet (64), is used to ensure the outlet (64) is properly formed. The outlet (64) may also be formed by having a half-shaped contour thereof be included in both the compressor cover and backplate mold portions (not shown). As such, the outlet (64) is formed along with the compressor cover (14) and backplate (16) in either the die cast or injection mold processes detailed above.

Aspects of the disclosure have been described herein in an illustrative manner, and it is to be understood that the terminology used is intended to be in the nature of words of description rather than limitation. Many modifications and variations of the present disclosure are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced other than as specifically enumerated within the description.