US3791766A

US3791766A - Hydraulic pressure generating device

Info

Publication number: US3791766A
Application number: US00222848A
Authority: US
Inventors: A Kikutsugi; Y Shimoyama
Original assignee: Tokyo Keiki Co Ltd
Current assignee: Tokyo Keiki Inc
Priority date: 1971-02-27
Filing date: 1972-02-02
Publication date: 1974-02-12
Anticipated expiration: 1991-02-12
Also published as: JPS4710902U; GB1329395A; DE2207678A1; SE372599B

Abstract

A hydraulic pressure generating device having a housing with air holes formed at least in its upper and lower walls, a partition wall with air holes to divide the housing into upper and lower rooms, a fan located in the upper room of the housing, a pressure compensation variable discharge type pump, a motor mounted in the lower room for driving the pump, and an oil tank disposed in the lower room and having soaked therein the pump. In this case, when the fan is operated, air is sucked into the housing from the air holes bored in the lower wall of the housing and is discharged out of the housing through the air holes bored in the upper wall of the housing to thereby cool the pump and the motor effectively.

Description

United States Patent [191 Kikutsugi et al.

[ 1 Feb. 12, 1974 1 HYDRAULIC PRESSURE GENERATING DEVICE [75] Inventors: Aisaku Kikutsugi, Kawasaki;

Yoshihisa Shimoyama, Tokyo, both of Japan [73] Assignee: Kabushikikaisha Tokyo Keiki (Tokyo Keiki Co., Ltd.), Tokyo, Japan 22 Filed: Feb. 2, 1972 21 Appl. No.: 222,848

[58] Field of Search... 417/367, 368, 222, 271, 313, 417/363, 366, 372, 435; 165/47; 184/104 3,080,495 Sudmeier 417/415 2,136,098 11/1938 Browne.... 417/363 X 1,953,473 4/1934 Fedders 417/363 X 2,297,220 9/1942 Hintze 417/372 1 3,369,736 2/1968 C0leman.. 417/372 3,372,863 3/1968 Bloom i 417/372 3,156,409 11/1964 Paugh 417/372 3,478,958 11/1969 l-linck 417/312 X Primary ExaminerWilliam L. Freeh Assistant E.mminerRichard Sher Attorney, Agent, or FirmGeorge B. Oujevolk [5 7 ABSTRACT A hydraulic pressure generating device having a housing with air holes formed at least in its upper and lower walls, a partition wall with air holes to divide the housing into upper and lower rooms, a fan located in the upper room of the housing, a pressure compensation variable discharge type pump, a motor mounted in the lower room for driving the pump, and an oil [56] References Cited tank disposed in the lower room and having soaked UNnED STATES PATENTS therein the pump. In this case, when the fan is oper- 2550 754 5,195] Baker [65/47 ated, air is sucked into the housing from the air holes 2347:9412 8/1953 Shaw v 47/435 bored in the lower wall of the housing and is dis- 3343609 10/|967 Dubin [65/47 charged out of the housing through the air holes bored 3,694,108 9/1972 Pensa 417/222 in the upper wall of the housing to thereby cool the 3,487,431 12/1969 Forkner. 417/372 X pump and the motor effectively. 2,299,233 10/1942 Hoffer 417/222 1 2,510,632 6/1950 Hemphill 417/366 9 Claims, 5 Drawing Figures 1 HYDRAULIC PRESSURE GENERATING DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a hydraulic pressure generating device.

2. Description of the Prior Art An ordinary hydraulic pressure generating device such as shown in FIG. 1 which is commonly referred to as a power unit for a numerically-controlled machine tool comprises a constant discharge type pump 1, a motor 2 for driving it, and an oil tank 3 containing an actuating oil 4 (hereinafter referred to as an oil). In this device, when the motor 2 rotates, the oil 4 is introduced through a filter 5 and a hose 6 into the pump 1, from which a constant amount of oil per unit time is continuously discharged. One part of the discharged oil is returned to the oil tank 3 through a line filter 7, a load 8 and a cooler 9. While, the oil discharged from the constant discharge type pump 1 is mostly fed through a relief valve 10 to the input side of the cooler 9 and is thereby cooled together with the oil applied thereto through the load 8 and then returned to the oil tank 3. Reference numeral 11 indicates a pilot line of the relief valve 10, 12 a drain pipe of the pump 1 and 13 a safety valve of the cooler 9.

With such a conventional device, a substantially constant amount of oil is always discharged from the pump 1 irrespective of a variation in the load 8 and the discharged oil is mostly returned to the oil tank 3 through the relief valve 10. Therefore, the utilization efficient factor of the oil is poor and a loss, viewed from the overall structure of the device, is great and, in addition, the temperature of the oil rises when it passes through the relief valve 10, which causes large vibration of the overall device. Further, since the oil is compressed by the relief valve 10, it rapidly deteriorates, which results in various bad influences such as generation of wear, damage and vibration of the instruments using the oil and so on.

SUMMARY OF THE INVENTION The present invention is to provide a hydraulic pressure generating device which is free from the aforementioned defects experienced in the prior art, and hence is highly efficient, capable of suppressing heat generation of the oil used, extending the lifetime of the instruments and oil and preventing deterioration of the oil and is inexpensive and good in appearance.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram showing a conventional type of hydraulic pressure generating device;

FIG. 2 is a schamatic diagram illustrating a hydraulic pressure generating device of the present invention;

FIG. 3 is a perspective view of the device of this invention;

FIG. 4 is a fragmentary cross-sectional view of the device of FIG. 3; and

FIG. 5 is a cross-sectional view showing one example of a pump for use in this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIGS. 2 to 5, one example of the hydraulic pressure generating device of this invention will hereinafter be described. In FIG. 2 reference numeral 21 designates a pressure compensating variable discharge type pump, which is driven a motor 22. Reference numeral 23 indicates an oil tank and 24 an oil contained therein. Reference numeral 18 identifies a load driven by the pump 21.

As shown in FIG. 3, a housing 25 as of iron or like material is provided, which is divided by a partition wall 26 into upper and

lower rooms

27 and 28 and a plurality of air holes 29 are formed in the partition wall 26. In the upper room 27 an exhaust fan 30 is disposed, which is driven by a motor, though not shown. In the lower room 28 the pump 21, the motor 22 and the oil tank 23 are housed. In this case, the pump 21 is disposed below the oil level 24a in the oil tank 23. In the illustrated example the motor 22 is attached to an upper wall 23a of the oil tank 23 with its rotary shaft 22a being held vertically and the pump 21 is disposed in the oil 24 and a rotary shaft 21a of the pump 21 is coupled by a coupling 31 with that 22a of the motor 22. Reference numeral 32 designates a fixture of the motor 22, 33 a fixture of the

pump

21, 34 an air escape bored in a case 21b of the pump 21 near the end of the shaft 210 at such a position as not to affect the bearing support, 340 an ordinary drain port and 35 a hose for supplying the oil discharged from the pump 21 to the outside, which hose is preferred to be formed of rubber or like elastic material.

The horizontal area of the oil tank 23 is selected to be relatively smaller than that of the lower room 28 of the housing 25, many radiation fins 36 are mounted on the outside of the oil tank 23 and slit-like air holes 37a and 37b are formed in the upper and lower walls 25a and 25b of the housing 25. Reference numeral 38 indicates support legs for supporting the oil tank 23. Between the legs 38 and the oil tank 23 the legs legs 38 and the lower wall 25b of the housing 25 are interposed vibration-proof members 39 as of rubber to prevent transmission of the vibration of the motor 22 and the pump 21 to the housing 25 and, further, vibrationproof rubber members 41 may be interposed between the housing 25 and its legs 40. In FIG. 4 reference numerals 42 and 43 designate adjusting levers respectively one ends of which project from the upper wall 23a of the oil tank 23,the former being used for adjustment of a pressure compensator and the latter for adjustment of the amount of the oil discharged by adjusting the inclination of an inclined plate of the pump 21.

FIG. 5 illustrates one example of the discharge type pump 21, in which reference numeral 44 indicates its drive shaft, 45 a swash-plate (inclined plate), 46 a piston, 47 a cylinder block, 48 a valve plate and 49 a pressure compensator. If necessary, filters may be provided before and after the pump 21.

With the present device described above, the hydraulic pressure of the oil discharged from the pump 21 and the amount of the oil discharged therefrom per unit time can be independently adjusted by manual operation of the adjusting levers 42 and 43 and even when the pump 21 is soaked in the oil and, further, these values can be set at minimum values corresponding to the load, so that ineffective power can be theoretically minimized and the required capacity of the motor 22 can be decreased. Further, although this device is applied to many kinds of apparatus, the number of the kinds thereof in view of the capacity of the pump 21 can be decreased and the hydraulic pressure generating device can be standardized and mass produced.

As will be apparent from FIG. 3, by the rotation of the fan 30, air enters the housing 25 from the air holes or slits 37b bored in the lower wall 25b to cool the oil tank 23, the pump 21 and the motor 22 and flows into the upper room 27 from the air holes 29 of the partition wall 26 and is then discharged from the housing 25 to the outside thereof through the air holes or slits 37a of the upper wall 25a. Accordingly, the oil tank 23, that is, the oil 24 is forcibly cooled, in which case the fins 36 formed on the outside of the oil tank 23 enhances the cooling effect. In accordance with the present device the pump 21, the motor 22, the oil tank 23 and so on are covered with the housing 25, so that the fins 36 on the oil tank 23 cannot be seen from the outside and do not defile the appearance of the device. Further, the shapes of the air holes 29 and slits 37b are selected and a pressure-reduced air layer is produced by the operation of the exhaust fan 30 in the housing 25. The air layer and the housing 25 effectively suppress propagation of mechanical vibration. In addition, the fins 36 serve to reinforce the oil tank 23.

By positioning the pump 21 below the oil level 24a of the oil 24, the suction resistance of the pump 21 is decreased to improve conditions for the generation of cavitation, which results in an increase in the efficiency of the pump 21 to alleviate the generation of vibration. When the pump 21 is soaked in the oil 24 as in the illustrated example, the drain pipe 12 depicted in FIG. 1 is unnecessary and accordingly the manufacturing cost can be curtailed and, at the same time, vibration of the pump 21 and propagation of its echo can be suppressed because the pump 21 is entirely enveloped in the oil. Further, the air escape 34 formed in the pump 21 facilitates deflation of the pump 21, which enables a supply of oil to internal lubricating units such as bearings of the pump 21 and so on to provide for prolonged lifetime thereof.

The hose 35 directly connected to the discharge port of the pump 21 is formed of an elastic or flexible material such as rubber and disconnected from the hose used on the side of the load. This allows ease in the fabrication of this device, enables prevention of mixing of a foreign substance into the oil and effectively absorbs pulsation of the discharged oil.

With the present invention, a minimum amount of oil can be circulated only to the load and since no relief valve is required, heat generation does not occur. Further, the oil is not sheared by the relief valve, so that deterioration of the oil is suppressed and heat generation is low to provide for enhanced efficiency of the cooling achieved when necessary and facilitate control of the oil temperature. Namely, this invention is capable of controlling the temperature and viscosity of the oil and maintenance of its quality which are important for lubrication of this kind of apparatus. Further, when employed in the hydraulic pressure system, wear of the pump shown in FIG. 5 is further reduced. The present invention dispenses with the line filter disposed understream of the pump which causes wear of the pump, permitting simplification of the construction of the device, coupled with the nonuse of the relief valve.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

We claim as our invention:

1. In a hydraulic pressure generating device including a housing having air holes formed at least in upper and lower walls thereof, a partition wall dividing the housing into upper and lower rooms and having air holes, a fan disposed in the upper room of the housing, a pressure compensation variable discharge type pump, a motor disposed in the lower room of the housing for driving the pump, and an oil tank disposed in the lower room of the housing and having the pump immersed therein, the improvement therein, wherein the shapes of the air holes formed in the partition wall and in the lower wall of the housing are selected to provide a pressure-reduced room in the housing, so that when the fan is operated, air is sucked into the housing from the air holes formed in its lower wall and is discharged out of the housing from the air holes formed in its upper wall, so as to cool the pump and the motor.

2. A hydraulic pressure generating device as claimed in claim 1, wherein radiation fins are provided on the oil tank.

3. A hydraulic pressure generating device as claimed in claim 1, wherein an air escape is formed in the case of the pump.

4. A hydraulic pressure generating device as claimed in claim 1, wherein a vibration-proof member is interposed between the oil tank and the housing.

5. A hydraulic pressure generating device as claimed in claim 1, wherein the housing is supported with a vibration-proof member.

6. A hydraulic pressure generating device comprismg:

a. a housing having air holes at least in upper and lower walls thereof;

b. a partition wall dividing the housing into upper and lower rooms and having air holes;

0. an exhaust fan disposed in the upper room of the housing;

d. a first motor disposed in the upper room for driving the fan;

e. a pressure compensation variable discharge type pump disposed in the lower room of the housing;

f. a second motor disposed in the lower room of the housing for driving the pump; and,

g. an oil tank disposed in the housing and having the pump immersed therein, whereby when the fan is operated, air is sucked into the housing from the air holes formed in the lower wall and then is exhausted out of the housing from the air holes formed in the upper wall.

7. A hydraulic pressure generating device comprising:

a. a housing having air holes at least in upper and lower walls thereof;

c. an exhaust fan disposed in the upper room of the housing;

(1. a first motor disposed in the upper room for driving the fan;

g. an oil tank disposed in the housing and having the pump immersed therein, wherein the shapes of the air holes formed in the partition wall and in the lower wall of the housing are so selected as to provide a pressure-reduced room in the housing.

in claim 7 in which an adjusting means is provided for adjusting a setting pressure of the pump from the outside of the tank.

Claims

6. A hydraulic pressure generating device comprising: a. a housing having air holes at least in upper and lower walls thereof; b. a partition wall dividing the housing into upper and lower rooms and having air holes; c. an exhaust fan disposed in the upper room of the housing; d. a first motor disposed in the upper room for driving the fan; e. a pressure compensation variable discharge type pump disposed in the lower room of the housing; f. a second motor disposed in the lower room of the housing for driving the pump; and, g. an oil tank disposed in the housing and having the pump immersed therein, whereby when the fan is operated, air is sucked into the housing from the air holes formed in the lower wall and then is exhausted out of the housing from the air holes formed in the upper wall.

7. A hydraulic pressure generating device comprising: a. a housing having air holes at least in upper and lower walls thereof; b. a partition wall dividing the housing into upper and lower rooms and having air holes; c. an exhaust fan disposed in the upper room of the housing; d. a first motor disposed in the upper room for driving the fan; e. a pressure compensation variable discharge type pump disposed in the lower room of the housing; f. a second motor disposed in the lower room of the housing for driving the pump; and, g. an oil tank disposed in the housing and having the pump immersed therein, wherein the shapes of the air holes formed in the partition wall and in the lower wall of the housing are so selected as to provide a pressure-reduced room in the housing.

8. A hydraulic pressure generating device as claimed in claim 7, wherein said pump includes a casing in which an air escape is formed in the casing of the pump.

9. A hydraulic pressure generating device as claimed in claim 7 in which an adjusting means is provided for adjusting a setting pressure of the pump from the outside of the tank.