Cross flow fan system

Abstract: In a cross flow type fan according to the present invention having a tongue section (3) provided between the rear guide surrounding the cross flow fan, the back side and bottom side thereof and the front side of the fan, a projecting section (10) (flow changing board) is provided on the rear guider (6), the shape of the tongue section is caused to be different at the middle section and at both ends of the axial direction of the fan, the boundary section of the suction opening and the blow off opening of the air is divided on the outward circumferential surface of the fan by means of the partition wall having continuous through holes, and the air flow direction control blade curved toward the blow off side is provided.

Description: BACKGROUND OF THE INVENTION The present invention relates to a cross flow fan system which is utilized for air conditioners and various other types of air conditioning systems. Example of a conventional cross flow fan: Fig. 2 is a structural diagram of a cross flow fan system for a conventional air conditioner. As shown in Fig. 2, the conventional cross flow fan system incorporates a cross flow fan 101 in a casing 103, and at a position close to the outer circumferential surface of the fan there is provided a tongue section 102 having the same cross section (which plays a role of dividing the suction side and discharge side) in an overall area in the direction of the shaft of the fan. Incidentally, 104 represents a discharge opening. In this case, the discharge flow rate at both ends 104a of the fan shown in Fig. 3 is less as compared with that of the middle section 104b of the same fan and there is a possibility of generating a reverse suction flow depending on the shape of the tongue section 102, causing instability in the discharge flow rate of the fan. Furthermore, if a load (105) such as a heat exchanger is provided on the suction side of the fan, there is a possibility of easily generating surging of the discharged air flow particularly in the low air volume range. In order to solve the problems described above, there has been an attempt to stabilize the discharged air flow at both ends 104a of the fan by providing from the side plate such a protruding portion (projection) 106 as shown by oblique lines on both ends 104a of the discharge opening. By using this method, the discharge flow rate of both ends 104a of the fan increases, making it difficult for surging to occur. However, depending on the position where this projection 106 is to be provided or the shape thereof, detailed experiments become necessary and there is a possibility of reduced discharge flow rate in some cases. GB-A-1 066 053 describes a cross-flow machine for inducing fluid flow comprising a rotor located within a housing having two opposed walls. In one of the walls there is provided a vortex guide having a cross-section which varies along the axial direction so that, for example, the cross-section at the ends of the vortex guide is different from that at the middle portion. This arrangement is stated to reduce the noise of the machine. SUMMARY OF THE INVENTION The present invention has been accomplished in order to solve the above-described conventional problems. According to the present invention, as defined by claim 1, there is provided a cross flow fan system having an inlet and an outlet, comprising: a rear guider defining a portion of the inlet and the outlet and having a rear side; a cross flow fan being rotatable to drive air from the inlet to the outlet of said system, said air being driven through a side of the cross flow fan next to said rear side of said guider by rotation of said cross flow fan; and a tongue extending along the length of the cross flow fan, said tongue being positioned between the rear guider and front side of the cross flow fan, the tongue having a cross sectional shape which is different at a middle section thereof as compared to the ends thereof; characterised in that the tongue has three contiguous surfaces, a first surface positioned adjacent the outlet in a direction generally parallel to a direction of travel of a majority of the air driven through the outlet, a second surface positioned such that, at any position along the length of the tongue, the cross-section of the second surface is tilted with respect to that of the first surface, and a third surface positioned generally perpendicular to the first surface, the width of the second surface at the middle section of the tongue being smaller than the width of the second surface at the ends of the tongue so that the space between the tongue and the outward circumferential surface of the fan is greater at said ends than at said middle section of the tongue. The preamble of claim 1 relates to the disclosure of GB-A-1 066 053. With respect to the above example of the conventional cross flow fan, the cross flow fan according to the present invention is composed so that the shape of the tongue section in close vicinity to the outward circumferential surface of the fan at both ends of the fan is caused to be different from that at the middle section of the fan. It is thus possible to reduce the instability of the air flow at both ends of the discharge opening and to increase the flow rate. As described in detail below in the embodiment of the present invention, it is possible to increase the discharge flow rate at both ends of the fan and to achieve the stabilization of the discharged air flow at the same both ends. In addition, a considerable reduction is achieved in the overall instability of the discharged air flow in the low air volume range when a load such as a heat exchanger is provided on the suction side of the fan. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more fully understood from the detailed description given hereinunder and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention and wherein: Fig. 1(1) and Fig. 1(2) are diagrams showing the shape of the tongue section in an embodiment of the present invention. Fig. 1(1) shows the shape of the tongue section in the middle section in the axial direction of the fan and Fig. 1(2) shows the shape of the tongue section at both ends in the axial direction of the fan. Fig. 2 is a cross sectional structural diagram of the cross flow type fan for a conventional air conditioner. Fig. 3 is a perspective diagram showing the discharging opening section of an air conditioner. Fig. 4 is a diagram showing experimental results of the static pressure distribution of the discharged air flow in case the tongue section of Fig. 1(1) and Fig. 1(2) is used. Fig. 5 is a diagram for comparing the wind velocity distribution in the axial direction of the fan between a case wherein the tongue section according to the present invention is used and a case wherein the conventional tongue section is used. DESCRIPTION OF THE PREFERRED EMBODIMENTS For the shape of the tongue section of the above example of the conventional cross flow fan, the one shown in Fig. 1(1) is common and is designed so as to obtain high air volume. As compared with the shape of the tongue section of Fig. 1(1), Fig. 1(2) shows the shape of the tongue section whose space with the outward circumferential surface of the fan is widened by tilting (107') the portion of the tongue section (tip of the tongue section) 107 in close vicinity of the outward circumferential surface of the fan in a direction along the length of the tongue so as to move away from the outward circumferential surface of the fan than the portion 107 shown in Fig. 1(1). With regard to the shape of the tongue section shown in Fig. 1(1) and Fig. 1(2) respectively. Fig. 4 shows a comparison of experimental results in which the static pressure distribution at the discharge opening 4. From the results shown in Fig. 4, it is known that the shape of the tongue section shown in Fig. 1(2) has higher static pressure distribution than that shown in Fig. 1(1). The shape of the tongue section shown in Fig. 1(2) is provided at both ends 104a of the fan, the entire tongue section is composed in the middle section 104b by using the shape of the tongue section shown in Fig. 1(1), and by increasing the static pressure of the discharged air flow at both ends l04a of the discharge opening higher than that at the middle section 104b, the pressure characteristic of the discharged air flow at both ends 104a is improved so as to obtain better stability. Fig. 5 is a diagram in which the wind velocity distribution of the discharged air flow in the axial direction of the fan is compared between the case where the tongue section according to a preferred embodiment of the present invention is used and the case of the tongue section of the conventional cross flow fan, and it is shown that the flow rate at both ends 104a of the preferred embodiment of the present invention is increased. As described above, according to the present invention, it is possible to improve the instability of the air flow at both ends 104a of the discharge opening which has conventionally been a problem. In addition, a considerable reduction is achieved in the overall instability of the discharged air flow in the low air volume range when a load such as a heat exchanger is provided on the suction side of the fan. While only certain embodiments of the present invention have been described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the present invention as claimed.

Claims: A cross flow fan system having an inlet and an outlet (104), comprising: a rear guider (103) defining a portion of the inlet and the outlet (104) and having a rear side; a cross flow fan (101) being rotatable to drive air from the inlet to the outlet (104) of said system, said air being driven through a side of the cross flow fan (101) next to said rear side of said guider (103) by rotation of said cross flow fan (101); and a tongue (102) extending along the length of the cross flow fan (101), said tongue (102) being positioned between the rear guider (103) and a front side of the cross flow fan (101), the tongue (102) having a cross sectional shape which is different at a middle section (104b) thereof as compared to the ends (104a) thereof; characterised in that the tongue (102) has three contiguous surfaces, a first surface positioned adjacent the outlet (104) in a direction generally parallel to a direction of travel of a majority of the air driven through the outlet, a second surface positioned such that, at any position along the length of the tongue, the cross-section of the second surface is tilted with respect to that of the first surface, and a third surface positioned generally perpendicular to the first surface, the width of the second surface at the middle section (104b,107) of the tongue (102) being smaller than the width of the second surface at the ends (104a,107') of the tongue (102) so that the space between the tongue and the outward circumferential surface of the fan is greater at said ends than at said middle section of the tongue. The cross flow fan system as recited in claim 1, wherein the width of the third surface at the middle section (104b,107) of the tongue (102) is greater than the width of the third surface at the ends (104a,107') of the tongue (102). The cross flow fan system as recited in claim 1 or claim 2, wherein air driven by the cross flow fan (101) and moving through the outlet (104) has a static pressure distribution at the outlet (104), the tongue (102) being positioned adjacent the outlet (104) and the difference in cross sectional shape of the tongue (102) causing air discharged through the outlet (104) proximate to the middle section (104b, 107) of the tongue (102) to have a lower static pressure than air discharged proximate to the ends (104a,107') of the tongue (102). The cross flow fan system as recited in any previous claim, wherein the rear side of the rear guider (103) forms a curved face, said curved face of the rear guider (103) being substantially continuous and uninterrupted to the outlet (104) of the system. The cross flow fan system as recited in any previous claim, further comprising a heat exchanger (105) positioned between the inlet of said system and said cross flow fan. The cross flow fan system as recited in claim 5, wherein air entering the inlet of the system passes through said heat exchanger (105), said heat exchanger (105) being inclined with respect to said rear side of said guider (103) whereby a current of air initially striking said heat exchanger (105) will be at an acute angle thereto.

Inventors: SHINOBU YOSHIHARU, TAKUSHIMA AKIRA, TANAKA SYOZO, YOSHIDA AKIRA, SHINOBU, YOSHIHARU, TAKUSHIMA, AKIRA, TANAKA, SYOZO, YOSHIDA, AKIRA
Applicants: SHARP KK, SHARP KABUSHIKI KAISHA
Application year: 1988
Main classification: F04D17
IPC codes: F04D17