GB2219845A - Parallel drive hydraulic motor system - Google Patents

Abstract

A parallel drive hydraulic motor system has at least one oil supply device (10), and a plurality of hydraulic motors (21 - 24) which receive oil pressure in parallel from the oil pressure supply device, the load of the output of the hydraulic motors being mechanically connected. The connection may be by way of gear wheels (31-34), an endless belt or chain (FIGS 3 and 4), material being rolled (FIG 6), or by the road engaged by wheels driven by the motors (FIG 9). <IMAGE>

Description

TITLE OF THE INVENTION PARALLEL DRIVE HYDRAULiC MOTOR SYSTEM AND HYDRAULIC MOTOR DRIVE VEHICLE BACKGROUND OF THE INVENTION From one aspect, the present invention widely relates to an oil pressure supply device and a drive device using a hydraulic motor connected to the oil pressure supply device, and particulary to a system in which a plurality of oil pressure motors are connected in parallel relation to one system of oil pressure supply device for driving thereof.

More particularly. it relates to a system in which output of the rotation of the hydraulic motors is mechanically connected with one another so as to provide an integrated output.

From another aspect, the present invention relates to a system in which vehicle wheels are directly driven by hydraulic motors.

From a further different aspect, the present invention relates to a vehicle compos i nOa a comb i nat i on of the f i rst - ment i oned invention only excluding a part of its constitution in which loads are connected with one another and the second-mentioned invent ion.

From a still further different aspect, the present invention relates to a device in which a plurality of oil pressure supply devices according to the first-mentioned invention are provided and the oil pressure supply devices are each provided with a hydraulic motor.

As conventional devices for supplying force of rotation, there have been known mechanical devices such as engine, shaft, differential gear, etc. used in automobiles or fluid-used devices such as hydraulic motor.

In the case of the above-mentioned hydraulic motor, it was merely driven alone.

In the case of the mechanical drive, means for transmitting force of rotation such as, for example, a shaft of an automobile, was required to be large enough to bear the transmitting force. Therefore, its weight was inevitably increased which resulted in decreased efficiency. Besides.. various losses such as friction losses or, where belts. etc. are used. slip losses were resulted. In the case of vehicle wheels. etc. wherein the final rotating bod was different in speed of rotation or the like, an adjusting means such as a differential gear was reuired. In the case of automobiles, losses due to its increased weight were serious. Besides, the costs for the additional parts inevitably invited the higher manufacturing costs of automobiles, etc.

On the other hand, a system such as a hydraulic motor in which only one fluid is used, is required to use a motor of maximum output when a large force of rotation is necessary. Therefore, there arose such problems as the position for locating such motor and as, especially when there are a plurality of members to be rotated such as wheels of automobiles, transmission of the force of rotation from the motor to each member to be rotated.

Therefore, it was considered that a plurality of such hydraulic motors are used and are driven in paral-lel. In this case, however, as shown in a partial block diagram of Fig. 2, if an attempt is made for connecting a plurality of hydraulic motors 20 to one system of oil pressure supply device 10 for rotating thereof, all of them are not simultaneously rotated due to irregularity of friction torque even if loads are not connected thereto. 'When one hydraulic motor having the least friction torque starts rotating, only that particular hydraulic motor does rotate, but the remaining hydraulic motors are not rotated unless the supplying quantity of oil is increased. When loads are each connected to each hydraulic motor, thet exhibit more ullstabTe action.Therefore, this kind of oil pressure device is not practicailS used - However, although the above-mentioned device is unstable, if the plurality of hydraulic motors are reviewed inrlividuallli, it is known that a constant torque characteristic can be obtained irrespective of the speed of rotation and in proportion to the supplying oil pressure. Therefore, the maximum characteristic thereof can be obtained depending on the usage thereof.

From this point of view, an idea came to the mind of the inventor of the present invention in that loads should be connected. The summary of the invention will be described hereinafter.

SUMMARY OF THE INVENTION From one aspect of the present invention (hereinafter sometimes referred to as the "first invention"), there is provided a parallel drive h > draulic motor system. It has one system of oil pressure supply device. It also has a plurality of hydraulic motors. The plurality of hydraulic motors receive supply of oil pressure in parallel from the oil pressure supply device, and loads of the output thereof are mechanically connected.

From another aspect of the present invention (hereinafter sometimes referred to as the "second invention") there is provided a hydraulic motor drive vehicle. It has a plurality of vehicle wheels. It also has a plurality of hydraulic motors. The plurality of hydraulic motors are adapted to directly drive the plurality of vehicle wheels.

From a further different aspect of the present invention (hereinafter sometimes referred to as the "third invention"). there is pro\'idt d a hydraulic motor drive vehicle. It has one system of oil pressure supply device. It also has a plurality of hydraulic motors. The plurality of motors receive supply of oil pressure in parallel from the one system of oil pressure supply device. It further has a plurality of vehicle wheels. The plurality of vehicle wheels are driven by the plurality of hydraulic motors respectively.

From a still further different aspect of the present invention (hereinafter sometimes referred to as the "fourth invention"), there is provided a hydraulic motor drive vehicle. It has a pluratity of systems of oil pressure supply device. It also has a plurality of hydraulic motors. The plurality of hydraulic motors received supply of oil pressure from the plurality of systems of oil pressure supply device respectively.

It further has a plurality of vehicle wheels. The plurality of vehicle wheels are driven by the plurality of hydraulic motors respectively.

Since the present invention is constituted in the manner as described in the foregoing, the following functions are produced.

In a parallel drive hydraulic motor system according to the first invention, one system of oil pressure supply device supplies oil pressure in parallel relation to the plurality of hydraulic motors. In the plurality of hydraulic motors, since loads of the output thereof are mechanically connected, they are rotated according to the ratio of connection of loads, respectively. Output thereof acts as an integrated output.

In a hydraulic motor drive vehicle according to the second invention, a plurality of hydraulic motors directly drive a plurality of vehicle wheels.

In a hydraulic motor drive vehicle according to the third invention, a plurality of hydraulic motors received oil pressure in parallel from one system of oil pressure supply device. The vehicle wheels are driven by the plurality of hydraulic motors respectively.

In a hydraulic motor drive vehicle according to the fourth invention, a plurality of hydraulic motors receive oil pressure from a plurality of systems of oil pressure supply device respectively. A plurality of vehicle wheels are driven by the plurality of hydraulic motors respectively.

BRIEF DESCRIPTlO OF THE DRAWINGS Fig. 1 is a side view of a partial block diagram of one embodiment of a parallel drive hydraulic motor system according to the present invention, Fig. 2 is a circuit diagram of a partial program diagram of its oil pressure supply device and hydraulic motors; Fig. 3 is a side view of load portion of another embodiment of a parallel drive hydraulic motor system according to the present invention; Fig. 4 is a side view of a load portion of a still another embodiment of a parallel drive hydraulic motor system according to tie present invention:: Fig. 5 is a side view of a partial block diagram of a still another embodiment of parallel drive hydraulic motor system according to the present invention; Fig. G is a side view of a load portion of a still another embodiment of a parallel drive hydraulic motor system according to the present invention; Fig. 7 is a plan view of vehicle wheels of one embodiment of a conventional two-wheel drive vehicle when the vehicle is turning to the right; Fig. 8 is a plan view of vehicle wheels of one embodiment of a conventional four-wheel drive vehicle;; Fig. 9 is a circuit diagram of one embodiments of the second and the third inventions in which a hydraulic motor drive vehicle according to tfie present invention is applied to a differential gear of a four-wheel drive vehicle; Fig. 10 is a circuit diagram of one embodiment in which a hydraulic motor drive vehicle according to the present invention is applied to a braking device of an automobile; Fig. 11 is a circuit diagram of a clutch of one embodiment in which a hydraulic motor drive vehicle according to the present invention is applied to the clutch of an automobile; Fig. 12 is a circuit diagram of one piece of anti-skid means of one embodiment in which a hydraulic motor drive vehicle is applied to the antiskid means of an automobile: wherein Fig. 12(A) is an illustration when not operated (when the hydraulic motor is connecte'l).. whereas Fig. 12(B) is an illustration when operated (when the nydraul ic motor is separated): Fig. 13 is a circuit diagram of one embodiment, in which a hydraulic motor drive vehicle according to the present invention is applied to sn endless orbit vehicle such as crawler; Fig. 14 is a schematic illustration showing a combination of the endless orbit portions thereof; Fig. 15 is a circuit diagram of another embodiment of flowing oil control means of a hydraulic motor drive vehicle according to the present invention, in which only one such example is shown; Fig. 16 is a graph showing the relation between the opening/closing degree of valves and oil quantity;; Fig. 17 is a graph showing the relation between the opening/closing degree of valves and a clutch; Fig. 18 is a circuit diagram of still another embodiment of flowing oil control means of a hydraulic motor drive vehicle according to the present invention; Fig. 19 is a circuit diagram of one embodiment of a parallel drive hydraulic motor system according to the fourth invention; and Fig. 20 is a circuit diagram of another embodiment of a parallel drive hydraulic motor system according to the fourth invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS Fig. 1 is a side view of a partial diagram of one embodiment of a parallel drive hydraulic motor system according to the present invention.

This system comprises one system of oil pressure supply device 10, and a plurality of hydraulic motors 20 connected to the one system of oil pressure supply device 10 in parallel relation so as to connect loads thereof. By this, the hydraulic motors 21, 22, 23, 24 are mechanically connected through loads 31. 32, 33, 34 as in the form of gears and become an integrated load 30 to produce output of rotation.

Fig. 3 is a side view of a load portion of another embodiment of a parallel drive hydraulic motor system according to the present invention.

In a mechanism in which. as shown in Fig. 3, a belt 30a or a chain is driven by a plurality of pulleys as loads 30, the pulleys 31a, 32a, 33a, 34a are each connected with a hydraulic motor 21, 22. 23, 24 (see Fig. 2) respectively. When a parallel drive is performed. all hydraulic motors are synchronized this time and start rotating at a constant torque. That is, the shaft output of the hydraulic motors are mechanically firmly connected by the pulleys and the belt, and therefore, all hydraulic motors can be rotated in synchronism.

Fig. 4 is a side view of a load portion of a still another embodiment of a parallel drive hydraulic motor system according to the present invention.

This embodiment is the same as that of Fig. 3 excepting that the diameters of the pulleys 31a through 34a for transferring a belt are different. In this way, even in the event that the diameters of the pulleys for transferring a belt are different, the driving is performed as long as they are in mechanical connecting relation. However, in that case. supposing the shaft torques of the hydraulic motors 21 through 24 are same drive force of the outer diameter of a pulley changes in inverse proportion to the diameter of the pulley.In this case. therefore, a regulator is linearly inserted in the hydraulic motors 22 and 23. and oil pressure in proportion tc) the diameter of a pulley is incurred, thereby the drive force of the outer diameter of the pulley can be equalized.

In the foregoing arrangement. although oil quantit. is increased compared with a case in which one pulley is driteii bS one hydraulic motor, the following advantages can be obtained. That is. a plurality of smail hydraulic motors are goods enough, oil pressure can he lowered. force incurred to the belt is dispersed. and good wear resistance and comparatixelv lono service life can be obtained. In short, the sum of output of the plurality (of hydraulic motors becomes the output of this system.

Fig. 5 is a side view of a partial block diagram of a still another embodiment uf a parallel drive hydraulic motor system according to the present invention.

In this was, two spur gears as the load 30 are combined in the proportion 2:1 and oil pressure applied to the hydraulic motor 21 connected to a small diameter gear 31b is reduced to a half of oil pressure applied to the hydraulic motor 22 at the side of the large diameter gear 32b, thereby force incurred to the meshing portion of the gears can be so small as just enough to regulate the synchronous speed of rotation of the hydraiti ic motor 20.

Therefore. the integrated output of the two hydraulic motors 21 anti 22 can be taken off from anywhere of the two gears 31b and 32b.

Fig.6 is a side view of a load portion of a still another embodiment of a parallel drive hydraulic motor system according to the present invention.

In th embodiment. the present invention is applied to a rolling machine. bhen a material 50 is rolled. it is a usual practice that the material 50. in nost cases. is rolled into multistage as shown in Fig.(3. In this case, although the line speed is increased in proportion to the rolling degree of the material 50, torques of pulleys or rolling rollers 31c through 34c are required to be constant irrespectine of the transferring speed.By connecting the hydraulic motors 21 through 24 to the transferring pulleys :31 through f-;4c and hs performing a parallel driving, the expected characteristic can be satisfied.

Fig. is a plane view of vehicle wheels according to one embodiment of a conventional two-heei drive vehicle when the vehicle is turning to the right.

Fiò.ô is likewise a plane view of vehicle wheels according to one embodiment of a conentional four-wheel drive vehicle.

In an automated vehicle having three wheels or more (the four-wheel drive vehicle is naturally included in this category), there are located an internal combustion engine or an electric motor as a prime mover, a clutch, a differential gear and a brake. When the concept of the present invention is introduced here, an epoch making power transmission mechanism can be obtained.

The procedure for obtaining such epoch making power transmission ,nechanistn will be described hereinafter. As means for controlling thereof, there are two different ways; one is a separately controlling means and the other is an integratelly control 1 ing means. For an easy understanding, the separately control nag means ill be described first.

There is provided a differential means. In reviewing a two-wtleel dr ,e vehicle having onlv front wheels 3ld :32d or only rear wheels 33d. 44d. power is transmitted. as shown in Fig.7. through a differential gear 70 in order to absorb the difference of the orbit distances between the right and left wheels when the vehicle is turning to the right.In a four-wheel drive s-ehicle. a more complicated mechanism is employed in order to obtain the same purpose iti that, as shown ic Fig.8, output of an engine 70 is distributed to the front and rear axles by a differential gear 60 and further distributed to the right and left wheels. The present invention will now be described.

Fig.9 is a circuit diagram according to one embodiment of the second and the third invention, in which a parallel drive hydraulic motor system according to the first invention is applied to a differential gear of a four wheel drive vehicle.

In the present invention, this differential gear 60 is not necessary.

That is. as shown in Fig.9, the hydraulic pump 11 direction connected to the engine 70 is served as an oil pressure supply device 10. and the four hydraulic motors 21 thorough 24 connected to the vehicle wheels 31d through 34.1 are connected in parallel relation. Due to the foregoing simple arrangement.

the differences between the right and left wheels, or between the front and rear wheels can be automatically absorbed by an oil pressure circuit irrespective of the running speed of the vehicle. Moreover, any one of the vehicle wheels an run at the same torque. This S a mechanical "connection with the hydraulic motors 21,22... by friction of the load :30. That is the vehicle wheels and the road surfac are in ioose mechanical connection with each other. and all moving wheels symmetrically transmit power at a constant torque. The baking operation will be described next.

Fig. 10 is a circuit diagram of one embodiment. in whicl a hydraulic motor drive vehicle according to the third invention is applied to a brah,llÖ device of an automobile.

In this embodiment, a flowing oil control means is used for a main circuit 81 or branch circuits 82 through 85 per each of the hydraulic motors 21 through 23. That is, as shown in Fig. 10, oil rate restricting means 91 through 95 such as a throttle valve, a servo valve and a proportional valve which can be controlled from outside are linearly inserted, thereby all wheels can be simultaneous braked or each wheel can be individuallb braked. The function of a clutch will be described next.

Fig. 11 is a circuit diagram of a clutch of one embodiment, in which a hydraulic motor drive vehicle is applied to a clutch of an automobile.

In this embodiment, the flowing oil control means 90 is also used for the main circuit 81 of oil pressure or the branch circuits & through 85 of each of the hydraulic motors 21 through 24. That is , as shown in Fig. 11.

means 90a for restricting oil quantity and abie to separate the power side and the load side such as a throttle valve. a servo valve and a proportional valve which can be control led from outside are inserted in parallel thereby clutching function can be effected on all wheels simultatleously or can be individually on each wheel. oreover, a half-clutch function can be performed in a mid-was stage in that tlie clutch is not completely separated. Aii antiskid function till be described next.

Fig. 12 is a circuit diagram of one anti-shid means of on embodiment.

in which a hydraulic motor drive vehicle according to the third invention is applied to an anti-skid means of an automobile, wherein Fig. 12a is an illustration when not in use (when the hydraulic mot()t is connected), whereas Fig. 12b is an illustration when in use (when the hydraulic motor is separated).

When only one wheel is slipped on a road surface having radical humps and valleys or by mad, etc., the anti-skid function can be obtained by detecting the rapid increase of oil quantity of the branch circuit (89 and others) at that portion and by actuating the switch valve 90a for mahing it possible to effect the clutch function. Of course, at that time, the hydraulic motors (21 and others) separated from the main circuit 80 are freeiy idly rotated and will not disturb the other rotating wheel. The same is true with respect to oil leakage caused by disorder of the hydraulic motor itself or breakage of the piping belonging to the output circuit. In this case, the disordered portion is automatically separated by exactly the same reason.

Similarly, even when it is locked or nearly locked due to disorder of the hydraulic motor itself or by rapid increase of loads thereby to rapidly reduced oil quantity. it is easy that a warning is issued utilising this detector or other suitable treatment is performed.

Because of the af o re - ment i oned reason, the conven t i otla I mechanica differential gear, brake device and clutch device can all be replaced with the hydraulic drive circuit. Thus, there can be obtained a hydraulic full-time four-wheel drive vehicle. This is not limited to the four-wheel drive vehicle.

It can of course likewise applied to two-wheel drive vehicle. Moreover, it can be also applied even to special vehicles having three wheels or more. An endless orbit vehicle such as a crawler will be described next.

Fig.13 is a circuit diagram of one embodiment, in which a hydraulic motor drive vehicle according to the third invention is applied to an endless orbit vehicle, and Fig.14 is illustration showing the combination of the end less orbit port ions thereof.

The present invention can be applied to an endless orbit(crawler) drive type vehicle. That is. as shown in Fig.13, one system of niain circuit 81 is connected with two systems of branch circuits 82 and 83. The branch circuits 82 and 83 are each provided with a flowing oil control means 90.That is, if means for controlling the oil pressure. oil quantity and switching of the direction is inserted therein respectively. the vehicle can be of course moved forward and backward by simultaneously driving the right and left endless orbits 31a and 32a? and in addition. the vehicle can be flirned from its stopping state by driving the right and left endless orbits 31a and 32a in the opposite direction w I th respect to each other.

Lastly there ill Le 'de.cr jed a modification in which the above.- mentioned flowing oil control means 90 becomes an integrated means.

Fig. 15 is a circuit diagram of another embodiment of a flowing oil control means of a hydraulic motor drive vehicle according to the third invention and only one is illustrated in the figure. A required number of the illustrated circuit may be connected in parallel relation according to necessity.

As apparent from the figure, there are provided flow rage control valves (throttle valves) 91b. 92b and 93b. i.e., flowing oil control means 90. which are linearly connected the main circuit 31. The central flowing rate control valve (throttle valve) 92b is connected with the oil pressure motor (21 and others) in parallel relation. The operation thereof will be described. The braking operation will be described first.

The second flowing rate control valve 92b is now in its completely closed state. If the first and the second flow rate control valves 91b and 93b are gradually closed from the completely opened state simultaneously or at the different time and finally brought to be in the completely closed state as shown in Fig. 16, the oil quantity Qw to be subjected to work is reduced and finally brought to be zero as seen from the figure. therefore. the hydraulic motor (actuator) is loched.

In this case, the first and the second flow rate control alves 1 ant 93b are completely closed and the second flo\ > rate control valve 02b is compietel opened thus allowing the vehicle to run by inertia. and then the second flow rate control valve 92b is gradually closed. Even in the foregoing state, the braking function is obtainable.

When the first and the third flow rate control valves 31b and 93b are throttled here. the working of the brake will be delicately different depending on the direction of rotation of the hydraulic motor. Therefore, it is sometimes more effective to control at different time rather than controlling simultaneously. The clutch will be described next.

The second flow rate control valve 92b is brought to be in its completely opened state. In the foregoing state, the first and the third flow rate control valves 91b and 93b are gradually opened. simultaneously or - at different time. from the completely closed state so as to increase the oil quantity Qw as shown in Fig. 17 and at the same time. the second flow rate control valve 92b is gradually throttled so as to reduce the oil quantity Qb for bypass. As a consequence. the clutch function can be obtained.

In the initial state where the first and the th i rd flow rate control valves 91b and 93b are completes closed and the second flow rate control valve 92b is completely opened. the hydraulic motor (21 and others) is separated from the main circuit 81 and rotated idly. The anti-skid function will be described next.

The first and the third flow ate control I valves 91 b and 3'b are completely closed and the second flow rate control valve 92b is completei- opened and the main circuit 31 and the branch circuits (82 and others) are separated by the afore-mentioned clutch function. As a result. tlie separated hydraulic motor is rotated idly and therefore. the vehicle wheel associated with that motor is rotated idly.

cci,lellt counter measure in this embod i ment will be describeil hereinafter.

When an oil leakage is occurred due to disorder of the hydraulic motor (21 and others) itself and/or breakage of wiring belonging to tie branch circuit (82 and others). the first and the third flow rate control valves 91b and 9:3b are completely closed and the second flow rate control valve 92b is completely opened. As a result, the hydraulic motor is separated from the main circuit S1. Therefore, the vehicle can be kept running by the remaining wheels. Anticipating such accident to occur, a detector for detecting rapid increase of oil quantity may be provided.When locked or nearly locked due to disorder of the hydraulic motor itself or due to rapid increase of loads. and as a result. the oil quantity Qw is rapidly reduced. the counter measure which was described in the column of individual means can be likewise employed.

With the above-mentioned constitution, there is such a significant characteristic in that energy can be recollected.

When the vehicle is running by. inertia. the hydraulic motor 20 acts as a hydraulic pump and working oil is reversely transferred to the main circuit 81. In order to rotate the hydraulic pump 11 connected to a prime mover, if the prime mover is of the' type for recollecting energy. the oil reversely transferred is returned back the inertial of the vehicle in the form of energy and at the same time is acted as braking function (as engine brake of a conventional vehicle).

Although the flow rate control valve has been described as a throttle valve, it may be any other suitable valve such as a servo valve and a proportional control valve as long as it is capable of controlling the flow rate. Furthermore. the flow rate control valve 90 shown in Fig. 12 may be inserted into the main circuit as shown in Fig. 18 so as to separate all branch circuits (82 and others). It may be inserted into the main circuit 81 and all the branch circuits (82 and others).

In all of the above-mentioned embodiments, the oil pressure supply device 10 may comprise one system of several such units as a group. Further, it is understood that the present invention is not limited to a hydraulic motor, but the technical scope of the invention includes all types of fluid motors which use liquid or gas. The reason is that the technical idea is the same for motors using other types of fluid.

Supposing the shaft output torques of the hydraulic motor are all the same, if the front and the rear wheels are different in outer diameter, the power for driving the portion contacting the ground is different. In order to make it same, a pressure reducing valve may be inserted into each hydraulic motor so as to establish an oil pressure corresponding to the outer tiiametel of the wheel. By this, it can easily cope with a sitliation in that although the outer diameter of the wheels is the same, the driving power is required to be changed per each wheel depending on the condit-ions of the road surface.If a pressure regulatiiig valve which can be regulated from outside is used instead of the pressure reducing valve, the driving power can be changed automatically or manually.

In this case, if the hydraulic motor is'of the type which can be rotated in both directions, it is required to insert the pressure reducing valves one each from each side of the motor in symmetrical relation.

Lastly, one embodiment of the fourth invention will be described . In this embodiment, the oil pressure supply device 10 of the first invention is modified as such that each hydraulic motor receives the supply of oil pressure from a plurality of systems of oil pressure supply device. Since the remaining constitution is all the same as the first invention, the description will be omitted.

In this case, as shown in Fig. 19, one drive source such as an engine may be connected with a plurality of oil pressure supply devices 10 such as a plurality of hydraulic pumps in tandem so as to be rotated simultaneously.

Otherwise. a plurality of driving sources may be connected with an oil pressure supply device 10 respectively. And. each branch circuit (82 and others) may be provided with a pressure reducing valve or other suitable means.

Furthermore this can also be applied to a vehicle. The description of the third invention is also quoted here. In this case, if the flowing oil control means is connected to the rotation of a handle of the vehicle so that oil quantity supplied to each hydraulic primp of teach wheel is controlled according to the angle of rotation thereof. As a result, a favorable operation and function can be obtained.

Since a parallel drive hydraulic motor system according to the present invention is constituted in the manner as described in the foregoing, the following significant effects can be obtained.

In the case a conventional mechanical drive device is replaced with the oil pressure drive device according to the present invention, in the oil pressure supply device, a hydraulic pump may be simply directly connected to a prime mover of a variable speed of rotation and variable or output (however. the speed of rotation of the prime mover is required to be used to that estent in that a cavitation is not taken place in the hydraulic pump). and this may be simply connected with the load (branch ci rcu it) through piping.The oil pressure devices such as the lydraul ic pump. the hydraulic motor and the valve, etc. can be easily made sinai I though they have coml)aratively large output , and the structures thereof are very simple. Therefore, a hydraulic motor can be embedded in the wheel portion of the driving wheel. and the piping materials can be freely select fro any desirable material such as meta; resin. rubber or the like according to purposes. Further. the lovating place of the mechanical driving devices can be freely designed. and the trouble rate of the devices ill be reduced in proportion to the simplicity of the devices will be reduced in proportion to the simplicity of the stricture.

moreover. the present invention can also be applied to a four-wheel steering automobile very easily. and the four-weels can be all steered by 90 degrees.

It can be not only moved forward and backward but it can be even moved sideward like the sidewise crawl of a crab.

Claims (16)

WHAT IS CLAIMED IS:

1. A parallel drive hydraulic motor system comprising a system of oil supply device, and a plurality of hydraulic motors which receive oil pressure in parallel from said oil pressure supply device load of the output of said hydraulic motors bering mechanically connected.

2. A parallel drive hydraulic motor system as claimed in claim 1, wherein said hydraulic motors receive oil pressure from said oil pressure supply device through flowing oil control means.

3. A parallel drive hydraulic motor system as claimed in claim 2, wherein said flowing oil control means is a controllable throttle valve.

4. A parallel drive hydraulic motor system as claimed in claim 2, wherein said flowing oil control means is a regulator.

5. A parallel drive hydraulic motor system as claimed in claim 2, wherein flowing oil control means is a controllable servo valve.

6. A parallel drive hydraulic motor system as claimed in claim 2, wherein flowing oil control means is a proportional control valve.

7. A parallel drive hydraulic motor system as claimed in claim 2, wherein said flowing oil control means is means for restricting oil quantity and for separating the power side from the load side.

8. A parallel drive hydraulic motor system as claimed in claim 2, wherein said flowing oil control means is means for controlling oil pressure, oil quantity and direction switch.

9. A parallel drive hydraul it-' motor system as claimed in claim 1, wherein the loads of the output of said hydraulic motors are connected with one another by friction.

10. A parallel drive hydraulic motor system as claimed in claim 1, wherein the loads of the output of said hydraulic motors are connected with one another by gear.

11. A parallel drive hydraulic motor system as claimed in claim 1, wherein said one system of oil pressure supply device comprises a plurality of hydraulic pumps.

12. A parallel drive hydraulic motor system as claimed in claim 1, wherein said flowing oil control means comprises three flow rate control valves (throttle valves) linearly connected with one another, and the center flow rate control valve is connected with the hydraulic motors in parallel relation.

13. A hydraulic motor drive vehicle comprising a plurality of vehicle wheels and a plurality of hydraulic motors for directly driving said plurality of vehicle wheels, respectively.

14. A hydraulic motor drive vehicle comprising one system of oil pressure supply device, a plurality of hydraulic motors which receive oil pressure in parallel from said oil pressure supply device, and a plurality of vehicle wheels driven b said plurality of hydraulic motors respectively.

15. A hydraulic motor drive vehicle comprising a plurality of system of oil pressure device, a plurality of hydraulic motors which receive the supply of oil pressure from said plurality of system of oil pressure supply device respectively, and a plurality of vehicle wheels driven by said plurality of hydraulic motors respectively.

16. A parallel drive hydraulic motor system substantially as hereinbefore described with reference to, and as illustrated in, Fig. 1, or Figs. 2 and 3, or any one of Figs. 4 - 6, or Fig. 9 or Figs. 9 and 10, or Fig. 11 or Figs. 12a and 12b, or Figs. 13 and 14, or Fig. 15 or any one of Figs. 18 - 20, of the accompanying drawings.