Air conditioner for vehicle with noise-reduction means

A flow straightening grid 30 is provided at an area where the air flow turns about 180 degrees in an air path 23, or in the vicinity thereof. Because of this, the air flow can be prevented from being disturbed in the air path 23 and, therefore, noise caused by the disturbance of the air flow can be reduced effectively.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an air conditioner for a vehicle.

2. Description of the Related Art

In a conventional air conditioner for a vehicle, noise generated when an air flow crosses an impeller and noise generated around a suction part and a discharge part of a cross flow fan (refer to JIS (Japanese Industrial Standard) B 0132 No. 1017) is reduced by providing a flow straightening grid at the suction side of the cross flow fan (refer to, for example, Patent document 1).

By the way, depending on the type of a vehicle, there may be a case where an inside/outside air switching unit has to be arranged at a place offset with respect to the rotation axis of a blower, that is, the blower itself, on account of restrictions of the arrangement in the vehicle, and if the inside/outside air switching unit is arranged offset with respect to the blower, in many cases, the inside air flow has to, for example, make a U-turn so as to turn the direction of flow about 180 degrees in the inside/outside air switching unit.

If an air flow makes a U-turn in the inside/outside air switching unit, the air flow is disturbed and noise is likely to be generated as shown inFIG. 7.

SUMMARY OF THE INVENTION

The above-mentioned problem being taken into consideration, the first object of the present invention is to provide a novel air conditioner for a vehicle different from a conventional one and the second object is to reduce noise caused by the disturbance of the air flow.

In order to attain the above-mentioned objects, in a first aspect according to the present invention, an air conditioner comprising: a blower (10) for sending air into a compartment; an inside/outside air switching unit (20) arranged on an air suction side of the blower (10) and for adjusting flow rate of inside air and flow rate of outside air to be supplied to the blower (10), and a flow straightening means (30) arranged on the way in an air path (23) from an air inlet (22) of the inside/outside air switching unit (20) to an air suction port (13a) of the blower (10) and for straightening air flow; wherein the air path (23) is formed into a U-turn shape, thereby the air flow turns substantially 180 degrees on the way in the air path.

Due to this, it is possible to reduce noise generated by the disturbance of the air flow because the air flow is prevented from being disturbed on the way in the air path (23).

In a second aspect according to the present invention, an outside air inlet (21) of the air inlet (22) of the inside/outside air switching unit (20) opens toward a direction substantially the same as that of the air suction port (13a) of the blower (10) and an inside air inlet (22) of the air inlet (22) of the inside/outside air switching unit (20) opens toward a direction substantially opposite to that of the air suction port (13a) of the blower (10).

In a third aspect according to the present invention, the flow straightening means (30) is arranged at an area, where the air flow turns substantially 180 degrees in the air path (23), or in the vicinity thereof.

In a fourth aspect according to the present invention, the flow straightening means (30) is made up so as to have a honeycomb structure in which a plurality of polygonal frame bodies are arranged in parallel to the air flow.

In a fifth aspect according to the present invention, the inside/outside air switching unit is arranged at a place offset toward a side with respect to a point right above the blower, either of the inside air inlet and the outside air inlet is open, as a suction inlet, at a lower portion of the inside/outside air switching unit and the air sucked from the suction inlet open at the lower portion makes a U-turn and is sucked by the blower, and a flow straightening member is provided at an area where the U-turn takes place.

By the way, the symbols in the brackets attached to each means are examples for showing the relation of correspondence with the specific means described in the later embodiments.

The present invention may be more fully understood from the description of the preferred embodiments of the invention set forth below, together with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the present embodiment, an air conditioner for a vehicle according to the present invention is applied to an air conditioner for a general passenger car, andFIG. 1is a top view of the air conditioner in the present embodiment,FIG. 2is a front view of the air conditioner according to the present embodiment,FIG. 3is a view in the direction of the arrow A inFIG. 2,FIG. 4is a schematic diagram of the air conditioner showing air flow, andFIG. 5Ais a sectional view along the line B—B inFIG. 4.

InFIG. 4, a blower10, which is an air sending means for sending an air into a compartment, comprises a centrifugal fan11for sending the air sucked from the direction of rotating axis radially outward, an electric motor12for rotating the fan11, a scroll casing13for accommodating the fan11and forming a scroll-shaped air path and, at the same time, for converting the dynamic pressure of the air discharged from the fan11into the static pressure, and so on.

An inside/outside air switching unit20has an outside air inlet21(refer toFIG. 1) for taking in the outside air and an inside air inlet22(refer toFIG. 2) for taking in the inside air, and adjusts the flow rate of inside air and the flow rate of outside air to be supplied to the blower10by adjusting the opening states of both inlets21and22by means of an inside/outside air switching door24(refer toFIG. 3), and the air introduced into the inside/outside air switching unit20is guided to the blower10, that is, to an air suction port13aof the scroll casing13.

By the way, the inside/outside air switching unit20is arranged offset with respect to the blower10and, at the same time, the outside air inlet21opens toward the direction substantially the same as that of the air suction port13aand the inside air inlet22opens toward the direction substantially opposite to that of the air suction port13aand, therefore, an air path23through which the inside air introduced from the inside air inlet22flows has a U-turn shape so that the air flow is turned 180 degrees in the air path23.

In the present embodiment, as the air suction port13aopens upward, the outside air inlet21opens substantially upward, as shown inFIG. 3, and the inside air inlet22opens substantially downward as shown inFIG. 2.

At an area where the air flow turns about 180 degrees in the air path23, a flow straightening grid30for straightening the air flow is provided as shown inFIG. 4. By the way, the flow straightening grid30according to the present embodiment has a honeycomb structure, as shown inFIG. 5in which a plurality of polygonal (hexagonal, in the present embodiment) frame bodies are formed by the use of film members made of a metal, such as aluminum, and the plurality of polygonal frame bodies are arranged in parallel to the air flow.

In this embodiment, fixing protrusions31, which are formed so as to protrude inward from an inner wall of the inside/outside air switching unit20, fix the flow straightening grid30to the inside of the inside/outside air switching unit20in such a way that the flow straightening grid30is sandwiched by the fixing protrusions31from an upstream side and a downstream side of the air flow of the flow straightening grid30.

To the discharge side of the blower10, an air conditioning unit40(refer toFIG. 1andFIG. 2) accommodating a temperature adjusting means, such as an evaporator and a heater, for adjusting the temperature of the air to be sent into a compartment and an air sending mode switching means for switching the air sending modes, and so on is connected.

Next, the features of the air conditioner for a vehicle according to the present embodiment are explained below.

In the present embodiment, as the flow straightening grid30is provided on the way in the air path23, it is possible to prevent the air flow from being disturbed on the way in the air path23. Further, noise caused by the disturbance of the air flow can be reduced.

By the way, the disturbance of the air flow is likely to occur at an area where the air flow turns about 180 degrees in the air path23or in the vicinity thereof, as shown inFIG. 4and, therefore, if the flow straightening grid30is arranged at the area where the air flow turns about 180 degrees in the air path23or in the vicinity thereof, as in the present embodiment, the disturbance of the air flow can be prevented efficiently.

FIG. 6shows the result of noise (SPL) measurement when the thickness of the flow straightening grid30, that is, the dimension of the portion of the flow straightening grid30parallel to the air flowing direction, is set to about 20 mm. From this result, it is found that by providing the flow straightening grid30when the air flow rate is 540 m3/h, noise is reduced by about 1.1 dB(A) and by about 1.5 dB(A) in the range between 125 Hz and 1 kHz.

OTHER EMBODIMENTS

In the embodiment described above, the air flow makes a U-turn when the inside air flows, but the present invention is not limited to this, and the air flow may make a U-turn when the outside air flows.

Moreover, in the embodiment described above, the flow straightening grid30is made up by the use of the honeycomb structure made of aluminum foil, but the present invention is not limited to this, but, for example, a wire mesh or the like may be used. However, if the flow straightening grid30is made up of the wire mesh, a large flow resistance of the air flow results, therefore, the size of the wire mesh should be taken into consideration.

While the invention has been described by reference to specific embodiments chosen for the purposes of illustration, it should be apparent that numerous modifications could be made thereto, by those skilled in the art, without departing from the basic concept and scope of the invention.