JPH11230568A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve efficiency and reduce pressure resistance of a front grill so as to reduce noise by forming a leading edge into almost an arc, maintaining a cross section width of a furring of the front grill, and decreasing the ratio of a center distance of the furring toward the direction of a suction port. SOLUTION: In an air conditioner having a front grill formed by a furring, an indoor unit of the air conditioner comprises a front grill 101 having a horizontal furring 102, a bell mouth 103, a fan 104, a heat exchanger 107 and the like. A distance between the furring 102 increases toward the center of a suction opening of the fan 104. It is desirable to arrange the ratio D/W of the maximum width D of the furring of the front grill to the center distance W of the furring to be approximately 0.1 to 0.2. According to this arrangement, pressure resistance is reduced, the air flow from an exhaust port is caused to be difficult to be sucked by the front grill, as a result of which, the noise level is reduced, and the efficiency of the air conditioner is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner and, more particularly, to an air conditioner having a front grill formed of horizontal rows.

[0002]

2. Description of the Related Art In a conventional air conditioner having a front grill composed of horizontal rows, a method of increasing the grill area and reducing the average flow velocity to the grill is generally used to reduce the pressure resistance caused by the front grill. It has been used extensively. This is because the reduction in pressure resistance is closely related to the reduction in noise. Therefore, in order to increase the air volume,
In order to reduce the pressure resistance, the area of the front grill had to be increased. In addition to reducing the pressure resistance, a method of reducing noise by reducing turbulence in the wake of the front grill by combining a front grill composed of horizontal rows and an air filter installed downstream thereof, JP-A-3-25
No. 5822. This is to reduce the turbulence by aligning the positions of the front grill bar and the reinforcing bar of the air filter to reduce the number of obstacles existing in the flow.

[0003]

In order to increase the air volume,
The front grill area needs to be increased. There was a problem that an increase in the area of the front grill led to an increase in product dimensions. In addition, air conditioners that are installed on the ceiling and that draw air through the front grill and blow out from around the front grill are designed to maintain the product dimensions in order to achieve small size and large air volume while maintaining the size of the front grill. When the size is increased, the end of the front grill is closer to the outlet, and the possibility that the blown air is sucked from the front grill increases. In such a situation, for example, in heating, there is a problem that the blown air hardly reaches the vicinity of the floor, so that only the vicinity of the ceiling is heated, and efficiency in terms of air conditioning is reduced. An object of the present invention is to solve the problems of the conventional example described above, suppress the re-suction of air from the above-described outlet, improve the efficiency of air conditioning, reduce the pressure resistance of the front grill, and reduce the noise level. An air conditioner is provided.

[0004]

In order to achieve the above object, the present invention provides a front grille having a maximum width in a cross section.
D, the ratio D / W of the center-to-center distance W of the bar to 0.1 to 0.2, in the cross-sectional shape of the front grill, the front edge is formed in a substantially circular arc, the cross-sectional width D of the bar of the front grill bar. The ratio D / W of the center-to-center distance W of the bar is made smaller in the direction of the inlet, and the cross-sectional height H of the bar of the front grille is made larger in the direction of the inlet.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A front grille and an air conditioner indoor unit equipped with the same according to one embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partial cross-sectional view of an air conditioner indoor unit that is installed indoors and performs air conditioning. The main unit of the air conditioner indoor unit has a front grille 10 with a horizontal row 102.
1, bell mouth 103, fan 104, fan drive motor 105,
Housing 106, heat exchanger 107, decorative panel 108, panel outlet 10
Consists of nine. Here, the interval between the bars 102 increases toward the center of the fan 104 suction port.

FIG. 2 shows the shape of a conventional front grille and the flow of wind. The air conditioner indoor unit generally has a flow rate range of 10 to 40 m ³ when its cooling capacity is in the range of about 1 to 6 hp.
/ min. Since the pressure resistance of an object is considered to be approximately proportional to the square of the velocity, it rapidly increases when the average wind speed exceeds 1 m / s. For this reason, it is desirable to set the speed to 1 m / s or less as much as possible. For example, in an air conditioner indoor unit that requires a flow rate of 20 m ³ / min, the area of the front grill is about 600 mm × 600 mm.

The ratio D / W of the conventional maximum width D of the front grille bar to the center distance W of the bar is about 0.25, and the actual opening area Sgt is 75% of the front grille area. The average speed U (m / s) calculated from the front grill area is expressed by equation (1), given that the flow rate Q (m ³ / min) and the front grill area is Sg (m ² ). The velocity u (m / s) of the air passing through the space is represented by equation (2).

[0008]

(Equation 1)

[0009]

(Equation 2)

Assuming that the average wind speed U is 1, the speed u of the air passing between the front grill bars is U / (1-0.25) = 1.33U, that is, about 1.33 times the average speed U. The flow around the front grill is reduced and considered as an enlarged flow path, and the pressure resistance is evaluated.

In the expansion and contraction channels, the pressure resistance due to the flow
Rp (Pa) is the speed of the part with the smallest area, the speed of the air passing between the front grilles at the front grille, u (m / s),
Using loss coefficient に due to area change and air density ρ,
(Mechanical Engineering Handbook: 4th edition of the Japan Society of Mechanical Engineers, pp. 8-19).

[0012]

(Equation 3)

When flowing into the crosspiece, as shown in FIG. 2, the width of the flow path is reduced from W by WW and the width D of the crosspiece. At 0.25, the resistance coefficient ζ of this part is about 0.1 (from the Mechanical Engineering Handbook: 4th edition of the Japan Society of Mechanical Engineers, pages 8-19, 8-20). In the case of outflow from the pier, as shown in FIG.
Just bigger. Because of this, the cross-sectional area becomes large, and it is considered as an enlarged flow channel. When D / W = 0.25, the resistance coefficient
Is about 0.06 (Mechanical Engineering Handbook: 4th JSME)
Versions 8-19, 8-20). The total pressure resistance is determined by adding the pressure resistance due to reduction and expansion, for example,
In the case of an air conditioner indoor unit that requires a flow rate of 20 m ³ / min and the front grill area is about 600 mm × 600 mm, the average speed
U is about 0.93 m / s, and D / W = 0.25,
1.23m / s. Assuming that the distance between the bars is 10 mm and the height H is 25 mm, the conventional front grill bar has a pressure resistance of about 0.14 Pa due to reduction and enlargement.

The pressure resistance Rf due to friction on the wall of the crosspiece when the crosspiece is considered to be infinitely long is calculated by using the Reynolds number Re and the cross height H using the distance WW between the crosses and the speed u between the crosses shown in FIG. And the expression
(4) (from Mechanical Engineering Handbook: 4th edition of the Japan Society of Mechanical Engineers, pp. 8-19).

[0015]

(Equation 4)

Here, ν is a kinematic viscosity coefficient. For example,
In an air conditioner indoor unit that requires a flow rate of 20 m ³ / min, if the area of the front grill is about 600 mm × 600 mm, the distance between the piers is 10 mm, and the pier height H is 25 mm, the Reynolds number is 800
Pressure resistance due to friction is about 0.15Pa,
It is almost the same as pressure resistance due to contraction and expansion.

FIG. 3 shows the cross section of the front grille of the present invention and the flow of wind. The maximum width D of the front grille bar of the present invention, the ratio D / W of the center-to-center distance W of the bar is about 0.1 to 0.2, and the intermediate value D / W = 0.15, the pressure resistance of the front grille bar is the same as above. To evaluate.

Since the actual front grill area Sgt is 85% of the front grill area Sg, when the inter-rail distance WW is the same as the conventional one, the average speed U and the inter-rail speed u are expressed by the following equation (1). Calculated from (2), the speed u between rails is U / (1-0.15) = 1.17U, that is, the average speed
It is about 1.17 times U. Similarly to the above, when flowing into the crosspiece, it is considered that the cross-sectional area becomes a reduced channel, and D / W = 0.15
Then, the resistance coefficient ζ of this part is about 0.06 (from Mechanical Engineering Handbook: 4th edition of the Japan Society of Mechanical Engineers, pages 8-19, 8-20). Similarly, when flowing out from the crosspiece, it is considered as an enlarged channel with a large cross-sectional area. When D / W = 0.15, the resistance coefficient こ の of this part is about 0.022 (Mechanical Engineering Handbook: The 4th edition of the Japan Society of Mechanical Engineers 8) -19, 8-2
From page 0). Therefore, the pressure resistance of the present invention is expressed as (0.0
6 + 0.022) × ρ × (U / (1-0.15)) 2 / 2Pa.

When the height H, the speed u, and the distance WW are the same, the pressure resistance due to the friction on the wall surface of the crosspiece becomes equal to the Reynolds number Re in the equation (4). The present invention also has the same value, and the difference between the enlarged and reduced pressure resistances is the amount of reduction in the pressure resistance of the front grille. Therefore, in the present invention, even if the center center distance W is 88%, the maximum width D of the front grille,
When the ratio D / W of the distance W between the centers of the bars is set to 0.15 which is the range of the present invention, the pressure resistance due to the friction on the wall of the bar does not increase, and as a result, the length of the front grill in the width direction of the bar is reduced by 12%. it can.

In the conventional air conditioner indoor unit requiring a flow rate of 20 m ³ / min, the area of the front grill is 600 m
What is about m × 600mm becomes 600mm × 527mm. If the distance between the piers is 10 mm and the height H is 25 mm, the average speed U is 1.
05m / s, which is higher than the conventional example, but the crossing speed u is 1.23
As with m / s, the pressure resistance due to contraction and expansion is about 0.08 Pa, which can be reduced to about 60% of the conventional value. As a result, the pressure resistance of the entire front grill is (0.15 + 0.14) = 0.29 in the conventional example.
Whereas, in the present invention, (0.15 + 0.08) = 0.23 Pa and 80
%. Furthermore, by making the direction in which the air flows into the front grill bar into a circular arc, the separation of air at the bar entrance can be suppressed, and the pressure resistance at the front grill bar can be reduced.

Regarding the reduction of air conditioning efficiency by sucking the discharged air from the front grille again, the area of the front grille can be reduced in the crosswise direction as compared with the conventional front grille. Is 6% of the width of the front grill, for example, for a front grill width of 600 mm, the distance can be 36 mm.

As shown in FIG. 4, the discharge air is disturbed and forms a stagnation region at a low speed on the front grille side of the discharge port. There is a possibility that the air in the stagnation region is entrained by the air sucked into the front grill and is sucked again from the front grill. In the present invention, since the distance between the discharge port and the suction position of the front grille closest to the discharge port can be increased, as shown in FIG. 5, the air in the stagnation region is entrained by the air sucked into the front grille. It becomes difficult. Thus, the possibility that the flow from the discharge port is sucked by the front grill is reduced.

Thus, the maximum width D of the front grille bar,
By setting the ratio D / W of the distance W between the centers of the bars to the value of the present invention, the pressure resistance can be reduced and the flow from the discharge port can be made harder to be sucked in by the front grill compared to the related art. Reducing the pressure resistance has the effect of reducing the noise level. Making the flow from the discharge port difficult to be sucked in by the front grill has the effect of increasing the efficiency of the air conditioner.

In an actual air conditioner indoor unit, since air is sucked through a bell mouth by a fan, the speed distribution of the front grill is not uniform, and the speed increases near the bell mouth. On the other hand, as a method of reducing the pressure resistance, it is conceivable to increase the center-to-center distance W of the bar near the bellmouth where the speed is high. Even if the distance D / W between the maximum width D of the front grille bar and the center distance W between the bars is kept constant and the center distance W between the bars is increased, the above-mentioned expansion and contraction loss factors are the same as the maximum width D. Because it is determined by the ratio D / W of the center-to-center distance W, it does not become smaller. In the present invention, the maximum width D of the front grille bar is fixed, the maximum width D of the front grille bar, and the center distance W of the bar.
The ratio D / W should be small near the center of the bell mouth and large near the discharge port. In this way, the above-mentioned expansion and contraction loss coefficients become smaller at the center of the bell mouth, and even if the speed is high, the pressure resistance does not increase so much and the pressure resistance of the front grill is reduced.

Further, as described above, when the center-to-center distance W of the bar is increased near the center of the bellmouth and the bar height H is not increased, the bar also serves as a strength member of the front grill. The strength of the entire front grill decreases. In order to avoid this, the height H is increased near the center of Bellmouth.
As described above, when the pressure resistance is reduced, the flow from the discharge port is prevented from being re-sucked from the front grill, and the strength is secured, the front grill of the present invention as shown in FIG. 1 is obtained. In addition, the front grill is often formed of resin, and considering the moldability (fluidity of the resin, curing time, etc.), it is better that the maximum width D of the front grill bar is constant. Can be compatible.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of an air conditioner indoor unit including a front grille according to one embodiment of the present invention.

FIG. 2 is a schematic view of the flow of wind of a conventional front grill.

FIG. 3 is a schematic diagram of a flow of wind in a front grill of the present invention.

FIG. 4 is a schematic diagram of a flow of wind near a discharge port of a conventional front grill.

FIG. 5 is a schematic view of a flow of wind near a discharge port of a front grill of the present invention.

[Explanation of symbols]

101: front grill, 102: front grill bar, 103:
Bell mouth, 104: fan, 105: fan drive motor, 106: housing, 107: heat exchanger, 108: decorative panel, 109: decorative panel discharge port.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuhisa Yagi 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Inside Hitachi Shimizu Engineering Co., Ltd.

Claims (4)

[Claims] In an air conditioner for sucking air through an inlet to an impeller, a front grill comprising a horizontal bar array is provided upstream of the inlet, and a ratio D of a cross-sectional width D of the bar to a center-to-center distance W of the bar is provided. An air conditioner characterized in that / W is 0.1 or more and 0.2 or less. 2. The air conditioner according to claim 1, wherein the front grill has a cross-sectional shape whose front edge is formed in a substantially circular arc. 3. A cross-section width D of the front grille according to claim 1, wherein the cross-section width D of the front grille is constant.
An air conditioner wherein the ratio D / W of the center-to-center distance W of the crosspiece is reduced in the direction of the suction port. 4. The air conditioner according to claim 3, wherein the cross section height H of the front grille is increased in the direction of the suction port.