Cooling system in construction equipment

Abstract: Cooling air is sucked from only a lower opening (29) formed in an upper rotating structure (14), and control valves (25) for controlling hydraulic actuators are disposed in the flowing path of the cooling air. A clearance is formed between an upright plate (28) which is a constituent of a frame of the upper rotating structure and a side (23a) of a hydraulic oil tank (23) of which side face faces the central portion of the upper rotating structure (14). The clearance is located above the lower opening, so that the cooling air flow along the side face of the hydraulic oil tank (23). To this tank side face is fixed a valve stand (26), and control valves (25) are attached to the valve stand (26). Thus, the construction is simple and the outside air can be sucked certainly.

Description: BACKGROUND OF THE INVENTION (FIELD OF THE INVENTION) The present invention relates to a cooling system for cooling an engine, a hydraulic oil tank and control valves which are all mounted mainly in construction equipment such as a hydraulic excavator or in a working vehicle. (DESCRIPTION OF THE RELATED ART) Fig. 6 is a sectional side view showing a part of an upper rotating structure of a small-sized excavator, which is disclosed in Japanese Utility Publication No. 32434/94. In an air introducing structure according to the prior art, as shown in Fig. 6. there is formed an air duct 3 for sucking the outside air from a lower opening 2. The air duct 3 surrounds at least a portion of an oil tank 4 while allowing the said portion of the tank to be positioned in an air intake clearance 5. Fig. 7 is a cutaway plan view showing the construction of an upper rotating structure 6 of a small-sized excavator which is disclosed in Japanese Patent Laid Open No. 237458/95. According to the prior art illustrated in Fig. 7. an air flow control plate 11 is provided in an engine accommodating portion 7. The air flow control plate 11 guides a part of cooling air which has passed an engine 8 toward a hydraulic oil tank 10 mounted in a tank accommodating portion 9. In the conventional air introducing structure shown in Fig. 6, the air duct 3 extends past the oil tank 4 from the lower opening 2. In the central portion of interior of the upper rotating structure of the small-sized excavator, there is little margin of space, so it is very difficult to arrange the air duct 3 there in. In the conventional structure shown in Fig. 7, the air which has passed a radiator 12 comes into abutment against the air flow control plate 11 and is partially turned back toward the engine accommodating portion 7, so that the cooling efficiency for the engine 8 is deteriorated and there is not attained a satisfactory cooling effect for the hydraulic oil tank 10. US 3788418 describes an excavator having a cooling system as defined in the preamble of claim 1. SUMMARY OF THE INVENTION It is an object of the present invention to provide a cooling system in construction equipment of which cooling system is simple in structure and capable of introducing therein the outside air certainly. It is another object of the present invention to provide a cooling system in construction equipment of which cooling system is capable of efficiently cooling a hydraulic oil tank and control valves for controlling hydraulic actuators. The construction equipment cooling system of the present invention comprises an upper rotating structure; an engine mounted in a rear portion of the upper rotating structure and having an engine fan; a radiator disposed in proximity to the engine fan; a hydraulic oil tank disposed beside the engine; and control valves for controlling hydraulic actuators. the control valves being disposed on a side of the hydraulic oil tank. A lower opening is formed in an underside of the upper rotating structure and below the control valves. With rotation of the engine fan, air for cooling the control valves is sucked through the said lower opening. Preferably, a clearance is formed between an upright plate as a constituent of a frame of the upper rotating structure and the side face of the hydraulic oil tank, and the foregoing lower opening is formed below the clearance. The cooling system may be designed so that the air for cooling the control valves is supplied through only the aforesaid lower opening. Moreover, the control valves may be attached to a valve stand fixed to the upper rotating structure. Further, a duct may be provided on an exhaust side of the radiator, thereby allowing the air to be discharged through the duct to an exterior of the upper rotating structure. In the present invention, the air which is sucked from the lower opening with rotation of the engine fan flows along the side face of the hydraulic oil tank. In this case. the air passes the control valves attached to the side face of the tank. Consequently, both hydraulic oil tank and control valves are cooled by the cooling air. Additionally, it is possible to effect maintenance by utilizing the foregoing clearance and thus possible to improve the maintainability. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side view of a small-sized hydraulic excavator equipped with a cooling system embodying the present invention; Fig. 2 is a partially cut-away plan view showing a principal portion of the cooling system disposed in an interior of an upper rotating structure of the hydraulic excavator illustrated in Fig. 1; Fig. 3 is a partially cut-away detail view of a portion indicated by the reference mark A in Fig. 2; Fig. 4 is a view as seen in the arrowed direction B-B in Fig. 3; Fig. 5 is a view as seen in the arrowed direction C-C in Fig. 3; Fig. 6 is a sectional side view showing a part of an upper rotating structure of a conventional small-sized excavator; and Fig. 7 is a cutaway plan view showing a construction of an upper rotating structure of another conventional small-sized excavator. DESCRIPTION OF A PREFERRED EMBODIMENT An embodiment of the present invention will be described in detail hereinunder with reference to the accompanying drawings. Fig. 1 is a side view of a small-sized excavator equipped with a cooling system (not shown in Fig. 1) embodying the present invention. In Fig. 1, the reference numeral 13 denotes a lower traveling structure, and the numeral 14 denotes an upper rotating structure, which is rotatably mounted on the lower traveling structure 13. A working attachment 15 is mounted on a front portion of the upper rotating structure 14. The whole of the attachment 15 is not shown in Fig. 1. A boom cylinder 16 is a hydraulic actuator for actuating the working attachment 15. Left and right traveling motors 17L and 17R are mounted to the lower traveling structure 13 on the left and right sides. The right traveling motor 17R is not shown in the figure because it is located on the opposite side, or hidden side, of the left traveling motor 17L. Fig. 2 is a partially cut-away plan view showing a principal portion of the cooling system disposed in the interior of the upper rotating structure 14. In the same figure, the numeral 18 denotes a water-cooled engine, numeral 19 denotes an engine fan, numeral 20 denotes a radiator, numeral 21 denotes a shroud provided on an intake side of the radiator 20, numeral 22 a duct provided on an exhaust side of the radiator 20, numeral 23 denotes a hydraulic oil tank, numeral 24 denotes a fuel tank, numeral 25 denotes control valves controlling hydraulic actuators mounted on the hydraulic excavator, and numerals 26 and 26' denote valve stands for supporting the control valves 25. These are all mounted in the upper rotating structure 14. Fig. 3 is a partially cut-away detail view of a portion indicated by the reference mark A in Fig. 2. In the same figure, the numeral 27 denotes a frame of the upper rotating structure 14, numeral 28 denotes a longitudinally extending upright plate as a constituent of the frame 27, and numeral 29 denotes a lower opening. Fig. 4 is a view as seen in the arrowed direction B-B in Fig. 3. In the same figure, numeral 30 denotes an under cover mounted on a bottom side of a rear portion of the upper rotating structure 14. Fig. is a view as seen in the arrowed direction C-C in Fig. 3. In the same figure, the numeral 31 denotes an opening for the engine fan 19 of which opening is formed in a rear surface of the shroud 21. The construction of the cooling system according to the present invention will now be described with reference to Figs. 1 to 5. In the present invention, as shown in Figs. 2 and 3, the engine 18 and the radiator 20 are mounted in the rear portion of the upper rotating structure 14. The hydraulic oil tank 23 is disposed on the side of the radiator 20. With rotation of the engine fan 19 the cooling air is sucked from only the lower opening 29 formed in the underside of the upper rotating structure 14. The cooling air flows through the path indicated with arrows in Fig. 3, then passes through the opening 31 for the engine fan (shown in more detail in Fig. 5) of the shroud 21 and further passes through fins (not shown) of the radiator 20, then flows through the duct 22 disposed on the exhaust side of the radiator 20 and is discharged to the exterior of the hydraulic excavator. In the above air flowing path are disposed the control valves 25 for controlling hydraulic actuators which valves become high in temperature with increase of the hydraulic oil temperature. The lower opening 29 is positioned in the clearance between the upright plate 28 as a constituent of the frame 27 of the upper rotating structure and an outer surface 23a of the hydraulic oil tank 23 of which outer surface faces the central portion of the upper rotating structure 14. The valve stands 26 and 26' are disposed near the outer surface 23a of the tank 23 along which the cooling air flows, and the control valves 25 are secured to those valve stands 26, 26'. The cooling air passes the outer peripheral surfaces of the control valves 25. The operation of the cooling system of this embodiment will be described hereinafter, In this embodiment, as the engine fan 19 rotates, the cooling air is sucked from only the lower opening 29 of the upper rotating structure 14. The cooling air is introduced upward while being guided by both the upright plate 28 of the frame 27 and the outer surface 23a of the hydraulic oil tank 23 opposed to the upright plate 28. The structure of the lower opening 29 used in this embodiment is simple and economical, not requiring any complicated mechanism. In this embodiment, moreover, since the hydraulic actuator controlling valves 25 are disposed in proximity to the outer surface 23a of the tank 23, the cooling air which has been sucked in passes both the tank outer surface 23a and the outer peripheral surfaces of the control valves 25. As a result, the hydraulic oil tank 23 and the control valves 25 are cooled by the cooling air. Thus, it is possible to reduce the temperature of the hydraulic oil and improve the maintainability of hydraulic devices (control valves 25 and other hydraulic devices not shown).

Claims: A cooling system in construction equipment, comprising: an upper rotating structure (14); an engine (18) mounted in a rear portion of said upper rotating structure (14) and having an engine fan (19); a radiator (20) disposed in proximity to said engine fan (19); a hydraulic oil tank (23) disposed beside said engine (18); control valves (25) for controlling hydraulic actuators, said control valves (25) being disposed on a side face of said hydraulic oil tank (23) and an opening formed in said upper rotating structure (14) through which air for cooling said control valves (25) is sucked with rotation of said engine fan (19); characterised in that the opening (29) is formed in an underside of said upper rotating structure and located below said control valves (25). A cooling system in construction equipment according to claim 1, wherein said opening (29) is located below a clearance formed between an upright plate (28) which is a constituent of a frame (27) of said upper rotating structure (14) and the side (23a) of said hydraulic oil tank (23). A cooling system in construction equipment according to claim 1, wherein the air for cooling the control valves is supplied from only said opening (29). A cooling system in construction equipment according to claim 1, wherein said control valves (25) are attached to a valve stand (26) fixed to said upper rotating structure (14). A cooling system in construction equipment according to claim 1, wherein a duct (22) is provided on an exhaust side of said radiator (20), and the cooling air is discharged through said duct (22) to an exterior of said upper rotating structure (14). A work apparatus comprising: an upper rotating structure (14); an engine (18) mounted in a rear portion of said upper rotating structure (14) and having an engine fan (19); a radiator (20) disposed in proximity to said engine fan (19); a hydraulic oil tank (23) disposed beside said engine (18); control valves (25) for controlling hydraulic actuators, said control valves (25) being disposed on a side face of said hydraulic oil tank (23); and an opening formed in said upper rotating structure (14) through which opening air for cooling said control valves (25) is sucked with rotation of said engine fan (19); characterised in that the opening (29) is formed in an underside of said upper rotating structure and located below said control valves (25). A work apparatus according to claim 6, which is a vehicle. A work apparatus according to claim 6, which is a hydraulic excavator.

Inventors: WATANABE HIROFUMI, WATANABE, HIROFUMI, Watanabe, Hirofumi c/o Yutani Heavy Industries Ltd
Applicants: KOBE STEEL LTD, KABUSHIKI KAISHA KOBE SEIKO SHO
Application year: 1997
Main classification: B60K11
IPC codes: B60K11, F25D1