Hydraulic power equipment

A liquid reservoir has a rectangular shell in which crossed first and second partitions form first, second, third and fourth rectangular liquid chambers. The partitions are impervious between the first and fourth chambers and apertured between the first and second, second and third, and third and fourth chambers. Liquid flows serially through the first, second, third and fourth chambers via the apertured partitions and such flowing liquid is subjected to a heat exchange in the first, second, third and fourth chambers.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The subject invention relates to hydraulic power plants and components 
therefor, to hydraulic power units, to hydraulic drives, tools and other 
equipment, to reservoirs, to methods and apparatus for providing hydraulic 
powers, to methods and apparatus for circulating a liquid in a reservoir, 
and to heat exchange techniques. 
2. Disclosure Statement 
This disclosure statement is made pursuant to the duty of disclosure 
imposed by law and formulated in 37 CFR 1.56(a). No representation is 
hereby made that information thus disclosed in fact constitutes prior art 
inasmuch as 37 CFR 1.56(a) relies on a materiality concept which depends 
on uncertain and inevitably subjective elements of substantial likelihood 
and reasonableness, and inasmuch as a growing attitude appears to require 
citation of material which might lead to a discovery of pertinent material 
though not necessarily being of itself pertinent. Also, the following 
comments contain conclusions and observations which have only been drawn 
or become apparent after conception of the subject invention or which 
contrast the subject invention or its merits against the background of 
developments subsequent in time or priority. 
Hydraulic power units typically include one or more reservoirs for the 
hydraulic fluid which is moved by one or more pumps driven by an internal 
combustion engine, an electric motor or other suitable drive. 
Existing hydraulic power units typically include automobile-type wheels 
carrying a heavy frame structure on which the motor and pump assembly are 
mounted apart from a reservoir facility and required accessories. 
Some existing hydraulic power plants and units have been equipped with heat 
exchange facilities, typically for cooling the circulating hydraulic 
fluid. Sometimes water required for cooling a hydraulically actuated tool 
has been used for this purpose. Existing heat exchangers in this respect 
have tended to remain within the confines of established heat exchanger 
technology. 
Reference may in this respect be had to U.S. Pat. No. 222,889, by J. B. 
Gathright, issued Dec. 23, 1879 for a faucet equipped with a helix 
immersible into a coolant, U.S. Pat. No. 745,499, by G. R. Jarman, issued 
Dec. 1, 1903 for a heat interchanger employing a double helix, U.S. Pat. 
No. 949,216, by A. C. Canida, issued Feb. 15, 1910 for a coil protector 
for coolers employing a helical tube immersed in ice, U.S. Pat. No. 
1,424,689, by C. W. Stone, for an air cooler with bifilar helix, U.S. Pat. 
No. 1,813,667, by H. L. Hartenstein, issued July 7, 1931, for an apparatus 
for cooling internal combustion engines having a helical coil exposed to 
cool air, U.S. Pat. No. 2,077,846, by R. M. McIlvana, issued Apr. 20, 1937 
for a milk cooler employing a bifilar cooling coil, U.S. Pat. No. 
2,292,692, by O. R. Huber, issued Aug. 11, 1942, for a liquid 
refrigerating unit including helical and serpentine cooling coils, U.S. 
Pat. No. 2,449,127, by H. W. Kleist, issued Sept. 14, 1948 for an 
apparatus for cooling the interior of containers, employing bifilar and 
serpentine cooling coils, U.S. Pat. No. 2,752,763, by O. J. Shepard, 
issued July 3, 1956 for a beverage cooling apparatus with finned cooling 
coils or tubing, and U.S. Pat. No. 3,556,199, by R. S. De Groote, issued 
Jan. 19, 1971 for free convection cooling method and apparatus with 
immersed radiator-type heat exchanger. 
One problem with a transfer of such heat exchange technology to the 
hydraulic power source area is that it is possible for hot hydraulic fluid 
to flow through the reservoir without being subjected to the desired 
cooling effect by heat exchanger means located therein. 
In a similar vein, existing hydraulic power units have a reservoir capacity 
which typically is significantly higher than the volume of the hydraulic 
fluid pumped per minute. By way of example, a rule of thumb in this 
respect is that the reservoir capacity should be up to two and one-half 
times as high as the volume pumped per minute. This in practice adds 
considerable bulk and weight to hydraulic power units and also requires 
the volume of stand-by oil or other hydraulic fluid to be rather high. Yet 
despite such high reserves, existing power units often are not able to 
effect a sufficient or optimum cooling of the circulating hydraulic fluid. 
This eventuates shut-downs or limits power capacity and unit performance. 
SUMMARY OF THE INVENTION 
It is a general object of this invention to overcome the disadvantages and 
satisfy the needs expressed or implicit in the above disclosure statements 
or other parts hereof. 
It is a related object of this invention to provide improved hydraulic 
power units. 
It is a germane object of this invention to provide improved methods and 
apparatus for providing hydraulic power. 
It is also an object of this invention to provide improved reservoirs. 
It is a further object of this invention to provide improved methods and 
apparatus for circulating a liquid in a reservoir. It is a related object 
of this invention to provide improved heat exchanger methods and 
apparatus. 
Other objects of this invention will become apparent in the further course 
of this disclosure. 
From a first aspect thereof, the subject invention resides in a method of 
circulating a liquid in a reservoir and, more specifically, resides in the 
improvement comprising, in combination, the steps of providing a 
rectangular shell for said reservoir, providing first and second partition 
means to form with said shell a first rectangular chamber in a first 
corner region of the shell, a second rectangular chamber in a second 
corner region of the shell, a third rectangular chamber in a third corner 
region of the shell, and a fourth rectangular chamber in a fourth corner 
region of the shell and adjacent said first chamber, said partition means 
being made impervious between said first and fourth chambers and being 
apertured between said first and second, said second and third, and said 
third and fourth chambers, flowing the liquid serially through said first, 
second, third and fourth chambers via said apertured partition means, and 
subjecting said flowing liquid to a heat exchange in said first, second, 
third and fourth chambers. 
From another aspect thereof, the subject invention resides in a method of 
providing hydraulic power and, more specifically, resides in the 
improvement comprising, in combination, the steps of providing a reservoir 
with n chambers for storing a hydraulic fluid, pumping said hydraulic 
fluid serially through said n chambers, and subjecting said hydraulic 
fluid to a heat exchange in said n chambers. 
From another aspect thereof, the subject invention resides in a method of 
providing hydraulic power with a hydraulic fluid pump driven by a motor 
and, more specifically, resides in the improvement comprising, in 
combination, the steps of providing a hydraulic fluid reservoir as a 
mounting structure for said motor and pump, rendering mobile said 
reservoir, motor and pump by connecting carriage wheels to said reservoir, 
mounting said motor and pump on said reservoir, and connecting the pump to 
the reservoir. 
From another aspect thereof, the subject invention resides in apparatus for 
circulating a liquid in a reservoir and, more specifically, resides in the 
improvement comprising, in combination, a plurality of n chambers in the 
reservoir for storing the liquid, an impervious partition between two of 
the n chambers, means connected to said chambers for flowing the liquid 
serially through said n chambers via said two chambers, and means in said 
chambers for subjecting said flowing liquid to a heat exchange in said n 
chambers. 
From another aspect thereof, the subject invention resides in a liquid 
reservoir comprising, in combination, a rectangular shell, crossed first 
and second partition means forming with said shell a first rectangular 
chamber in a first corner region of the shell, a second rectangular 
chamber in a second corner region of the shell, a third rectangular 
chamber in a third corner region of the shell, and a fourth rectangular 
chamber in a fourth corner region of the shell and adjacent said first 
chamber, said partition means being impervious between said first and 
fourth chambers and being apertured between said first and second, said 
second and third, and said third and fourth chambers, means connected to 
said first and fourth chambers for flowing liquid serially through said 
first, second, third and fourth chambers via said apertured partition 
means, and means in said first, second, third and fourth chambers for 
subjecting said flowing liquid to a heat exchange in said chambers. 
From another aspect thereof, the subject invention resides in a hydraulic 
power unit and, more specifically, resides in the improvement comprising, 
in combination, a hydraulic fluid pump and motor driving same, a hydraulic 
fluid reservoir interconnected with said pump and including a mounting 
structure for said motor and pump, and means for rendering mobile said 
reservoir, motor and pump, including carriage wheels connected to said 
reservoir.

DESCRIPTION OF PREFERRED EMBODIMENTS 
The mobile hydraulic power unit 10 according to the preferred embodiment of 
the subject invention shown in FIGS. 1 and 2, includes a hydraulic fluid 
pump assembly 12 and a motor or engine 13 driving same. A hydraulic fluid 
reservoir 14 is interconnected with the pump assembly 12 and includes a 
mounting structure for the motor and pump 12 and 13. According to the 
illustrated preferred embodiment of the subject invention, carriage wheels 
15 and 16 are connected to the reservoir 14 for rendering mobile such 
reservoir, as well as the motor and pump 12 and 13. In short, the carriage 
wheels 15 and 16 are part of means for rendering mobile the reservoir 14, 
motor and pump 12 and 13, or generally the hydraulic power unit 10. 
The illustrated power unit 10 thus embodies a method of providing hydraulic 
power with a hydraulic fluid pump assembly 12 driven by a motor 13. 
According to a preferred embodiment of the subject invention, this method 
comprises, in combination, the steps of providing a hydraulic fluid 
reservoir 14 as a mounting structure for the motor and pump 12 and 13, 
rendering mobile the reservoir, motor and pump by connecting carriage 
wheels 15 and 16 to the reservoir, mounting the motor and pump 12 and 13 
on the reservoir as shown in FIGS. 1 and 2, and connecting the pump to the 
reservoir. 
In practice, such construction and combination according to the illustrated 
preferred embodiment of the subject invention makes for hydraulic power 
units which are less bulky, lighter and less expensive than prior-art 
hydraulic power units of comparable performance and capacity. 
Further according to an embodiment of the subject invention, the reservoir 
14 includes or is formed as a mounting base for the motor and pump 12 and 
13. This mounting base forms a structural part of the reservoir 14 on 
which the motor and pump are supported. The reservoir 14 with carriage 
wheels 15 and 16 thus is a chassis for the motor and pump 12 and 13. 
By way of example, the reservoir 14 comprises or is formed as a shell 17 
having a lid 18. It is then this reservoir lid 18 which constitutes or is 
formed as a mounting base for the motor and pump which are supported on 
such lid 18 as seen in FIGS. 1 and 2. In this respect, and within the 
scope of the subject invention, the pump or pump assembly 12 may, if 
desired, be mounted on the reservoir structure 14 or lid 18 separately 
from the engine 13. Alternatively, and as shown in FIGS. 1 and 2, the pump 
assembly 12 is mounted on the engine 13 and is thus supported or mounted 
on the reservoir structure 14 or lid 18 via the engine 13. In other words, 
motor and pump may be mounted as an assembly or unit on the reservoir 
structure or lid. 
In the preferred embodiment shown in FIGS. 1 and 2, the carriage wheels 15 
and 16 are attached to the shell 17 of the reservoir 14. In particular, 
the reservoir structure or shell has or is provided with lateral wheel 
mounting bases 20 and 21, which preferably are integral with or part of 
the reservoir structure or shell. 
The carriage wheels 15 and 16 are attached to the wheel mounting bases 
laterally of the shell 17. In other words, the wheel mounting bases 20 and 
21 carry the wheels 15 and 16 laterally of the reservoir shell 17 for 
rotation about an axis. 
By way of example, the motor 13 may be a diesel or other internal 
combustion engine, and a fuel tank 23 may be supported by the reservoir 
structure 14 either directly, or as shown in FIG. 1, via the engine 13. 
Alternatively, an electric motor may be mounted on the reservoir structure 
for driving the pump assembly 12. 
The reservoir 14 or lid 18 may carry further parts of the hydraulic unit 
10, such as a lateral frame structure 24 including fabricated tubing 25 
and screening 26 providing the unit in effect with appropriate protective 
side wall portions. 
The motor and pump unit 12 and 13 is mounted on the reservoir lid 18 via a 
motor base 28 and blocks 29. Other accessories, such as a hydraulic oil 
filter 31, may be directly attached to the reservoir 14 or shell 17. Yet 
other accessories, such as a control panel 32, may be supported by the 
tubing 25. In this respect, the tubing 25 forms the frame 24 which is 
supported via blocks 33 on the lid 18 of the reservoir 14 which is of 
itself a mounting frame for the equipment 12, 13, 23 and 32, in accordance 
with the illustrated preferred embodiment of the subject invention. 
In the preferred embodiment illustrated in FIGS. 1 and 2, the means for 
rendering the hydraulic unit mobile include one or more secondary or 
swivel wheels 35 in addition to the main carriage wheels 15 and 16. 
By way of example, the secondary wheels 35 are mounted on a swivel 36 which 
is pivoted on a bracket 37 attached to the reservoir 14 or shell 17. In 
particular, the shell 17 may have fore and aft mounting bases 38 and 39 
which preferably are integral with or a part of the reservoir shell 17. 
The hydraulic oil filter 31 is then attached to the front mounting base 
38, while the swivel wheel bracket 37 is attached to the rear mounting 
base 39. The swivel bracket 37, in turn, may serve as a mounting base for 
further acessories, such as an electric battery or power source 41 for 
supplying, for instance, starting current for an electric starter 
associated with the engine 13. 
The reservoir 14 and associated equipment may be protected by bumpers 42 
and 43 attached to the reservoir shell 17 at the mounting bases 38 and 39, 
respectively. 
According to the preferred embodiment of the subject invention shown in 
FIGS. 1 and 4, the reservoir 14 has a rectangular shell 17 which, by way 
of example, may be prismatic or, as shown in the drawings, may have the 
configuration of a truncated pyramid having a rectangular base. As seen in 
FIGS. 1, 2 and 4, lateral mounting bases 20, 21, 38 and 39 may be provided 
on or integral with the shell 17 in a cross pattern. Alternatively or 
additionally, a plurality of projecting ribs 45 may be provided along or 
across the walls of the reservoir shell 17. In practice, the projections 
20, 21, 38, 39 and 45 provide the reservoir shell with structural strength 
and also constitute heat sinks and cooling fins with respect to hot oil 
circulating the reservoir 14. Structural strength is also provided by 
crossed partitions 46 and 47 which are particularly effective in 
supporting the reservoir walls when the hydraulic fluid is drawn out of 
the reservoir by the pump assembly 12. The reservoir 14 may thus be cast 
or molded inexpensively and with relatively thin walls of a light-weight 
material, such as aluminum or an aluminum alloy. 
As seen in FIGS. 3 and 4, crossed first and second partition means 46 and 
47 form with the shell 17 a first rectangular chamber 51 in a first corner 
region of the shell, a second rectangular chamber 52 in a second region of 
the shell, a third rectangular chamber 53 in a third corner region of the 
shell, and a fourth rectangular chamber 54 in a fourth corner region of 
the shell 17 and adjacent the first chamber 51. The partition means 46 are 
impervious between the first and fourth chambers 51 and 54, but are 
apertured between the first and second chambers 51 and 52, the second and 
third chambers 52 and 53 and the third and fourth chambers 53 and 54, 
respectively. By way of example, apertures 55 are shown in FIG. 4 in solid 
lines in the partitions between the first and second and third and fourth 
chambers, while dotted lines in the partition between the second and third 
chambers indicate one or more apertures 55 in FIG. 3. 
As more fully described below, liquid, such as a hydraulic fluid, is flown 
serially through the first, second, third and fourth chambers via the 
apertured partitions of the partition means 46 and 47. This liquid or 
hydraulic fluid is subjected to a heat exchange in the chambers 51, 52, 53 
and 54. 
In the illustrated preferred embodiment of FIG. 3, the heat exchange means 
thus provided include a first heat exchanger 56 in the first chamber 51, a 
second heat exchanger 57 in the second chamber 52, a third heat exchanger 
58 in the third chamber 53 and a fourth heat exchanger 59 in the fourth 
chamber 54. 
As seen at 56, helically wound tubing may be employed to provide the 
desired heat exchange means. On the other hand, other types of heat 
exchange elements may, if desired, be employed to provide the heat 
exchange means, as generally indicated by blocks at 57 to 59 in FIG. 3. 
The heat exchangers 56 to 59 are connected in series, such as by tubing 61 
to 63. If desired, the heat exchangers 56 through 59, including tubing 61 
to 63, inlet tubing 65 and outlet tubing 66, may advantageously be formed 
of a single tube or of a couple of series-connected tubes. 
As indicated at 59 in FIG. 3, the heat exchange means may be cooling means 
or coolers. In particular, a coolant, such as cold water, may be applied 
from a source or water outlet 68 to the inlet tubing 65, to be serially 
circulated through the first, second, third and fourth heat exchangers 56 
to 59, so as to remove heat from, or lower the temperature of, hydraulic 
fluid in the chambers 51 to 54 of the reservoir 14. The heat exchange or 
cooling medium supplied by the source 68 preferably may be a coolant for 
the tool 69 which is driven by hydraulic fluid from the unit 10. In that 
case, the hydraulic fluid in the reservoir 14 is cooled by the coolant for 
the tool 69. 
The currently discussed method of operating a hydraulic tool 69 thus stores 
a hydraulic fluid in a reservoir 14, circulates the hydraulic fluid 
through the reservoir 14 and tool 69 for driving such tool, supplies to 
the tool 69 a further fluid, such as cold water from the source 68, having 
a temperature difference relative to the hydraulic fluid in the reservoir 
14, and effects a heat exchange between such further fluid and the 
hydraulic fluid. 
As seen in FIG. 3, the further fluid, which may be cold water or another 
coolant for the tool 69, may after circulation through the heat exchangers 
56 to 59 in reservoir chambers 51 to 54, be applied by a spray nozzle or 
similar outlet 71 to a rotary blade 72 or other active portion of the tool 
69 which heats up during operation thereof. 
Hydraulic fluid for driving the hydraulic tool 69 is applied thereto 
through a supply line 73, to be subsequently removed therefrom through a 
return line 74. In practice, the supply and return lines 73 and 74 may 
include piping, tubing, hoses or combinations thereof, as desired or 
necessary for a given tool or task. 
As seen in FIG. 2, the return line 74 enters the hydraulic unit, such as at 
the control panel 32, to be applied to the oil filter 31 via a line 75. A 
line 76 applies the filtered oil or hydraulic fluid to the reservoir 14 
and thus constitutes a reservoir inlet leading into the first chamber 51. 
Because of the imperforate nature of the partition 46 between the first 
and fourth chambers 51 and 54, the hydraulic fluid entering the reservoir 
14 cannot immediately depart from the reservoir through its outlet 78, 
largely in circumvention of the heat exchanger or cooling means 56 to 59. 
Rather, the imperforate nature of the latter partition in effect forces 
the hydraulic fluid to flow serially through all chambers 51 to 54 via 
apertures 56, in heat exchange relationship with all heat exchangers 56 to 
59. 
In the illustrated preferred embodiment, all portions of the circulating 
hydraulic fluid are thus subjected to a full cooling cycle. In the 
embodiment shown in FIGS. 1 and 2, the reservoir hydraulic fluid outlet is 
part of a line 78 connected to an inlet of the pump assembly 12. Hydraulic 
fluid is thus drawn into the reservoir 14 via return lines 73 and 75 and, 
after circulation through all chambers 51 to 54, is pumped out of the 
reservoir via line 74, to be applied to the hydraulic fluid supply line 73 
via an internal line 79. Hydraulic fluid is thus circulated through a 
closed circuit including pump assembly 12, reservoir 14, and lines 73 and 
74, thereby driving the active part of the tool 72. 
In practice, the pump assembly 12 may include more than one pump driven by 
the engine or motor 13. For instance, the assembly 12 may include two 
pumps which may be operated singly, alternatively, in parallel or in 
series as far as the delivery of hydraulic fluid from or through the 
reservoir is concerned, in order to operate two or more hydraulic tools 
via two or more sets of supply and return lines at the same time, or in 
order to operate larger, as well as smaller hydraulic tools as desired or 
required for a given task. In addition to instruments for indicating 
hydraulic pressure and other operating parameters, the control panel may 
thus include manually operated valves for switching various pump and fluid 
line combinations. 
By way of background and as indicated above, the rule of thumb heretofore 
was that reservoir capacity should significantly exceed pump volume per 
minute of a hydraulic power unit. In particular, a widely used rule 
dictated a reservoir capacity of two and a half times hydraulic fluid 
volume pumped per minute. 
Because of the features of the subject invention herein disclosed, the 
capacity of the reservoir 15 may in practice be significantly lower than 
the hydraulic fluid pumped per minute. By way of example, a prototype of 
the hydraulic power unit shown in FIGS. 1 to 4 is able to pump 20 gallons 
per minute with a reservoir capacity of only 12 gallons; that is, of only 
60% pump capacity, as contrasted to the 250% of the above mentioned rule 
of thumb. 
The latter prototype according to the subject invention is capable of 
delivering hydraulic oil at a pressure of 1,500 to 1,700 pounds per square 
inch. Because of the heat exchange or cooling system and 
compartmentalization of the reservoir shown in FIG. 3, such prototype 
working with tap water as a coolant is able to cool the above mentioned 
circulating oil from 140.degree. F. at the input line 76 to room 
temperature at the supply line 73. 
To These and similar ends, the subject invention provides methods and 
apparatus for circulating a liquid in a reservoir 14 by providing a 
plurality of n chambers 51 et seq. in the reservoir for storing the 
liquid, providing an impervious partition 46 between two chambers 51 and 
54 of the n chambers, flowing the liquid serially through the n chambers 
via the mentioned two chambers 51 and 54 and subjecting this flowing 
liquid to a heat exchanger in the n chambers. 
The reservoir 14 is in effect subdivided into n chambers, whereby the n 
chambers actually constitute subdivisions of the reservoir 14. Apertured 
partitions 47 are provided between one of the two chambers 51 and 54 and a 
third of the n chambers, and between that third chamber and the other of 
the two chambers 51 and 54. It is thus within the broad contemplation of 
the subject invention that the regions 52 and 54 shown in FIG. 3 may be 
implemented in the form of one third chamber in addition to the two 
mentioned chambers 51 and 54. 
However, for larger pumping capacities or cooling effects, it is preferable 
to provide at least the four chambers 51 and 54 and to aperture the 
partitions 46 and 47, but only between one of the two chambers 51 and 54 
and a third chamber 52 of the n chambers, between such third chamber 52 
and a fourth chamber 53 of the n chambers, and between a fourth chamber 53 
and the other chamber 54 of the mentioned two chambers 51 and 54. Suitable 
partition apertures have been shown at 55 in FIGS. 3 and 4. 
As seen in FIG. 3, the desired heat exchange or cooling is effected 
successively in the n chambers 51 to 54, while liquid is flown from one of 
the two chambers 51 serially through n-2 chambers to the other of the two 
chambers 54. 
As diagrammatically illustrated in FIG. 3, the pumped hydraulic fluid may 
drive a hydraulic tool 69 requiring a further operating fluid having a 
temperature difference relative to the hydraulic fluid. The desired heat 
exchange in the n chambers 51 to 54 may then be effected with the further 
operating fluid supplied from the source 68 via heat exchangers 56 to 59 
and spray nozzle 71. 
The subject extensive disclosure renders apparent or suggest to those 
skilled in the art various modifications and variations within the spirit 
and scope of the invention.