GB2218951A

GB2218951A - Power transmission system of vehicles

Info

Publication number: GB2218951A
Application number: GB8812415A
Authority: GB
Inventors: Hiroshi Sato
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-05-27
Filing date: 1988-05-25
Publication date: 1989-11-29
Also published as: JPH0771898B2; GB8812415D0; JPS63297126A

Abstract

A power transmission system of vehicies has wheels; fluid pressure motors 20 each connected to each wheel; fluid pipings for connecting the fluid motors in parallel relation; and main fluid pressure circuits each connected to the corresponding fluid piping. <IMAGE>

Description

TITLE OF THE INVENTION POWER TRANSMISSION SYSTEM OF VEHICLES BACKGROUND OF THE INVENTION This invention relates to a vehicle in a broad sense.

Particularly, this invention relates to a power transmission system from one aspect (hereinafter referred to as the first invention). From another aspect, it relates to a power transmission system with a brake mechanism (hereinafter referred to as the second invention).

More particularly. the first invention relates to a power transmission system of vehicles such as automobiles utilizing a fluid pressure such as an oil pressure as a power source. whereas the second invention relates to a power transmission system of vehicles such as automobiles in which the first invention + the pressure of a fluid such as oil pressure are utilized as a brake mechanism.

In conventional vehicles, power is transmitted from a power source such as an engine to the wheels through a mechanical connection of a shaft and a differential gear.

Further, in a convention brake mechanism for parking utilizing the engine, the engine is mechanically connected to the wheels to prevent the rotation of the wheels.

In this case, the mechanical structure of the power transmission system becomes very complicated and its weight is increased. As a result, the -fuel charges are increased.

Furthermore, due to limitation from the mechanical structure.

they are not suitable t steer the whole wheels and the steering angles are also limited.

In addition. if mechanisms such as a clutch and a whole wheel drive are added, their mechanisms become multiplicatively complicated.

Therefore. problems regarding the first invention also has its own problems as will be described. which can not be seen in the prior art.

SUMMARY OF THE INVENTION The present invention has been accomplished in order in view of the above problems.

A power transmission system of vehicles according to the first invention has solved the above problems by providing a fluid pressure motor such as a hydraulic motor to each wheel.

The second invention comprises the first invention plus a brake mechanism, in which a mechanical pressure is normally applied to wheels in order to prevent the rotation thereof. and a counter pressure is obtained from a fluid pressure. so that the braking is not acted on the wheels when the fluid pressure is present, but the braking is automatically acted thereon when the fluid pressure is not present.

The concrete structure of a power transmission system of vehicles according to the present invention will be described in detail.

First, there are wheels of a vehicle. Next. there are fluid pressure motors. Each of the fluid pressure motors is connected to each wheel. Further, there are fluid pipings. the fluid pipings are adapted to connect the fluid pressure motors in parallel relation. Lastly, there are main fluid pressure circuits. Each of the main fluid pressure circuits is connected to the corresponding fluid piping.

Since the second invention is constituted based on the first invention, the whole description of the first invention is quoted here. And. the description on the constitution of the second invention as will be described hereinafter is added thereto. The second invention is a constitution as a conventional parking brake and a constitution which takes the place of a short time engine brake, and offsets the weak point of a brake mechanism as a fluid pressure motor.

This is a means directly or indirectly provided to each wheel and which acts on the wheel, directly or indirectly. for preventing the rotation thereof by a mechanical pressure such as a spring, and by rendering a counter force with a fluid pressure from the main fluid pressure circuit by a fluid pressure cylinder such as hydraulic cylinder, the braking is not acted on the wheel while the fluid pressure is present. but the braking is acted on the wheel while the fluid pressure is not present.

With the above mentioned constitution of a power transmission system of vehicles according to the present invention. the following functions are produced.

A fluid pressure motor is connected to each wheel, fluid pipings are adapted to connect the fluid pressure motors in parallel relation, and the main fluid pressure circuits are connected to the corresponding fluid pipings, Accordingly, each wheel is driven by a fluid pressure motor such as a hydraulic motor provided thereto.

Since the second invention is eonstituted based on the first invention. the whole description of the first invention is quoted here.

And. the following description on the functions is added thereto. These are functions which take the place of the conven- tional engine brake and offset the weak points of a brake mechanism as a fluid pressure motor such as a hydraulic motor.

A mechanical pressure such as a spring directly or indirectly mounted on the wheel prevents, directly or indirectly the rotating force of the wheel. Ey rendering a counter force with a fluid pressure from the main fluid pressure circuit by a fluid pressure cylinder such as a hydraulic cylinder, the brazing is not acted on the wheel while the fluid pressure is present, but the braking is acted on the wheel while the fluid pressure is not present.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side view of one embodiment of a power transmission system of vehicles according to the first invention: Fig. 2 is a plan view of Fig. 1; Fig. 3 is an enlarged front sectional view of a wheel portion thereof; Fig. 4 is an enlarged front sectional view of a wheel portion according to another embodiment; Fig. 5 is an enlarged side schematic view of a hydraulic motor.

Fig. 6 is a front sectional view of an independently suspending wheel and a flexible piping portion: Fig. 7 is a schematic front view showing an axle and its vicinity; Fig. 8 is a front sectional view of a hydraulic motor and a wheel and its vicinity according to still another embodiment; Fig. 9 is a front sectional view of like part of Fig. 8 according to still anther embodiment; Fig. 10 is a front sectional view of a shaft and a wheel and its vicinity according to still another embodiment; Fig. Ii is a front sectional view of a wheel and a hydraulic motor and its vicinity of a motorcycle; Fig. 12 is a side view of Fig. 11; Fig. 13 is a schematic side view of a parking brake portion according to one embodiment of the second invention; ; Fig. 14 is likewise a schematic side view of a parking brake portion according to'anotherembodiment; Fig. 15 is a circuit diagram of one embodiment of a hydraulic circuit employed in the second invention; Fig. 16 is a front sectional view of a hydraulic motor and its vicinity according to another embodiment of the first invention: Fig. 17 is a front view of a gear according to another embodiment of the hydraulic motor: Fig. 18 is a side sectional view of Fig. 17 but having a cover; and Fig. 19 through 25 are modified embodiments thereof.

wherein; Fig. 19 is a sectional view: Fig. 20 is a side view; Fig. 21 is front sectional view; Fig. 22 and 23 are front views: and Fig. 24 and 25 are side sectional views.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A power transmission system of vehicles according to the present invention will be described in detail with reference to the illustrated embodiment.

FIG. 1 is a side view of a' power transmission system of vehicles according to one embodiment of the invention (the first invention).

Fig. 2 is a plan view of Fig. 1.

Reference numeral 10 denotes an automobile as a vehicle and 11 denotes wheels thereof. 20 denotes hydraulic motor as one example of a fluid pressure motor. Each of the hydraulic motors 20.

as illustrated in Fig. 2, is connected to each of the wheels 11.

30 denotes oil Pressure pipings. The pipings 30 are adapted to connect the hydraulic motors 20 in parallel relation. 40 denotes main oil pressure circuits. The main oil pressure circuits 40 are connected to the corresponding oil pressure pipings 30.

In a vehicle having four wheels or more. the wheels are usually held in a cantilever fashion. In a two-wheeled vehicle, the wheels are mostly held from both sides thereof,- Therefore, in order to build an oil pressure motor in the wheel. as the front sectional view showing this portion in Fig. 3. an external rotor type motor is advantageous. Of course. as the front sectional view showing this portion in Fig. 4, an internal rotor type motor is good enough. At present, various configurations of internal rotor type hydraulic motors are proposed. Since they are well known per se, the description will be omitted. In the current market, the external rotor type is seen in an electric motor but hardly seen in a hydraulic motor.The reason seems to be that there is no demand for it. - One example of the external rotor type hydraulic motor will be described with reference to Fig. 5. As seen in the figure. an elliptical stator 25 is secured, a plurality of vanes 23 are provided at the inner side of a rotor 22 having a circular inner wall, and the vanes 23 are urged against the stator 25 by springs 24 or oil pressure. Both ends in the long diameter direction of the stator 25 are contacted with the inner wall of the rotor 22.

When oil is supplied to the IN side of the stator 5 and when the OUT side thereof is connected to a tank the external rotor 25 starts rotation. The internal stator of the hydraulic motor 20 is not limited to the elliptical configuration as in this embodiment. Instead. it may take any non-circular configuration having a long and a short diameters.

In the case of an independent suspension, flexible pipings 30 are provided at the foremost ends thereof with quick couplers 31 and 41 as shown in Fig. 6, so that the flexible pipings 30 can be connected to the main oil pressure circuits 40 through the quick couplers 31 and 41. In the case of a penetration shaft suspension used in a truck or the like. as a front sectional view of this portion shown in Fig. 7, an axle may be provided at each end thereof with a hydraulic motor built-in type wheel. In the case of a double tire, as is shown in Fig. 7, two tires may be regarded as one wheel 11. In the case the hydraulic motor 20 and the wheel 11 are separated from the other. the hydraulic motor 20 and the wheel 11 may be placed separately from the other.In this case, as the front sectional views of the embodiments of this portion shown in Figs. 8 and 9, the hydraulic motor 20 is mounted to the vehicle body, so that the wheel is driven by a universal joint 12. Due to the foregoing arrangement. the weight under the spring 13 can be reduced and thus convenient.

In the case of a tractor. the trailer is merely trailed.

However, if it is made in an oil pressure drive type, the trailer side can also be driven easily as shown in Fig. 1. Moreover.

since the hydraulic motor itself has the braking function. too.

two pipings are just enough in view of its own nature of the oil pressure circuit. In the case of a double tire as shown in Fig.

2, two tires may be regarded as one tire.

A vehicle, which is used for agriculture or work in mountains and forests, must be designed to have a sufficient space from the ground to the bottom of the body because it runs on a ground having a lot of humps'and valleys. Further, it must be designed, as much as possible not to have projections other than the wheels 11. In this case. the oil pressure drive type is advantageous, too. To this end, as is shown in Fig. 10, the vehicle body is provided with tubular shafts 14 projecting therefrom. and a built-in type wheel 11 is mounted on each of the tubular shafts 14. The oil pressure piping 30 for driving the hydraulic motor 20 may be inserted through the shaft 14. The steering is also made possible by of the shaft 14.In the case of a four-wheeled vehicle, therefore four wheel drive and four wheel steering can be performed simultaneously. This is also applicable to vehicles having a larger number of wheels such as a six-wheeled vehicle with ease.

As a very interesting one, there is an embodiment in which the present invention is applied to a two-wheeled vehicles are of rear wheel drive, and the front wheel is used for steering. If this conventional two-wheeled vehicle is designed to have an oil pressure drive system, the front wheel drive is available with ease. As is shown in Fig. 11, if the wheel 11, in which the hydraulic motor 20 is embedded and which is held in a cantilever fashion, is mounted on the front wheel and connected to the main body through the flexible piping 30 and couplers 40 and 41, it becomes able to run by two wheels. Although the piping is exposed in Fig. 12, it may be inserted through a supporting mechanism 15.

The supporting mechanism 15 employed in this embodiment may of course be of a cantilever type.

Since the second invention is based on the first invention.

the description of the first invention is all quoted here. The following description is to be added to the foregoing description. That is, it is a constitution which takes the place of the conventional engine brake and is a mechanism which offsets the weak points of a brake mechanism as a fluid pressure motor.

Although the hydraulic motor has the braking function. too.

it is not sufficient when it is used for parking for a long time.

If the hydraulic motor is of a vane type, oil leaks a little.

Complete prevention of the oil leakage for a long time is not advantageous in view of costs. Therefore, if it is used for parking, a mechanical brake must be built in the wheel. More specifically, an oil pressure cylinder is used so that when oil pressure is occurred, the brake is released. When the foregoing arrangement, when the engine is stopped and when the oil pressure becomes zero, the braking is naturally effected. The braking may be manually effected by pulling a bar as in the conventional manner.

The brake may be either a drum type or a disc type. In the case the parking brake is released-by a hydraulic motor. the way of application of the oil pressure is different depending on the state of the vehicle, suchas, for example, the accelerator is stepped in, the vehicle is running by inertia or engine brake is working. In a extreme case, a negative pressure is applied.

Therefore. in a parking brake 50 comprising a spring. etc. as shown in Fig.13 or Fig.l4, when pressure is accumulated by an accumulator 54, etc. in an oil Pressure circuit as shown in Fits. 15 and when the engine is working, the oil pressure must be always present so as to be able to release the parking brake 50. With the foregoing arrangement. as soon as the engine is stopped. a switch valve S is turned on with one shot in order to lower the oil pressure.

The concrete constitution thereof will be described hereunder. It is a means which is mounted, directly or indirectly, on the wheels 11, and in which a brake member 52 is tightened by a mechanical pressure such as a spring 51 or the like so as to prevent, directly or indirectly, the rotating force of the wheel 11, and by rendering a counter force with the oil pressure cylinder 53 by a fluid pressure from the main fluid pressure circuit 40, the braking is not acted on the wheel 11 while the oil pressure is present there, but the braking is acted on the wheel 11 while the oil pressure is present.

In a vehicle of an oil pressure drive system, it is very difficult to completely prevent the leakage of oil of a hydraulic pump and a hydraulic motor. Therefore, it should be designed as such that the leaked working fluid can be collected. In particular, an oil leakage measurement of the hydraulic rotor embedded in the wheel must be taken into a good consideration. One embodiment of the constitution will be described hereunder.

Two flexible hoses (for the use of P, T port) are required for pipings 30 and 40 disposed between the vehicle 10 and the hydraulic motor 20. In addition, one more hose is prepared for drain collection pipings 32 and 2.

Therefore, three hoses in total are required for one wheel.

In the hydraulic motor 20, as a front sectional view around this portion shown in Fig. 16, an oil pool is formed with a drain collection cover 60 for covering the oil leaking place, and flexible collection pipings 32 and 42 are connected through couplers 33 and 43, and the drain is collected to a tank by a pump having a small capacity. Of course, the collection pump may be omitted, and it may be collected to the tank by a natural pressure of the drain As a possible divisional applLcation in the future. another embodiment of the outer rotor motor will be described.

As the hydraulic - motor, there is an internal gear motor which is commercially available. This internal gear motor is modified in order to make an outer rotor motor 120. The first one is shown in the plan view of Fig. 17 and in the side-sectional view of Fig. 18. For an easy understanding, Fig. 17 illustrates only the combination of gears. As shown in Figs. 17 and 18, an idle gear 121 and a main gear 122 are intersected at right angles, both the gears 121 and 122 are sealed with a cover 123.

and a working fluid is pushed in through an oil pressure inlet port 125 disposed in the vicinity of a meshing potion 124 as shown by an arrow and discharged from an oil Pressure outlet port 126 disposed in the other direction, thereby to rotate the gears 121 and 122. The gears 121 and 122 intersecting at right angles may be formed in an umbrella shape as shown in Figs. 19 and 20.

Instead of the gears intersecting at right angles, the teeth of the main gear wheel 122, as shown in Fig. 21, may be formed in the inner side on the outer periphery, so that the teeth may be meshed with the idle gear 121.

In such construction as described above, a filler piece which is required for an ordinary internal gear motor. is not required any more. A rotation torque Ft of this type of motor is represented by the following formula; Ft = A x n x Ps wherein A is the sectional dimension (tooth height x tooth width) of the meshing portion of the gear wheel. n is the number of the idle gears and Ps is the oil pressure.

Therefore, in order to increase the torque with a constant oil pressure, the number of the idle gear 121 must be increased or the sectional dimension A must be made large. Specifically.

those shown in figures following Fig. 22 inclusive can be considered. As is shown in Fig. 22. one piece of main gear 122 is provided with a Plurality of idle gears 121a through 121n. and each of the idle gears 121a through 121n is provided with an inlet port and an outlet port. Further, as is shown in Fig. 23, the main gear 122 may provided to the front and back, ,and the idle gears 121, which are required for it, may also be provided.

Otherwise, as is shown in Figs. 24 and 25, two of the main gears 122 may be formed integrally. By the foregoing structure, the outer rotor motor 120 is accomplished.

With the above-mentioned constitution, ,a power transmission system of vehicles according to the present invention produces the following effects In a vehicle such as an automobile or a two-wheeled vehicle which runs by oil pressure, since the hydraulic motor is small and light compared with the engine, each of such hydraulic motors can be mounted to each wheel separately.

In this way, by providing hydraulic motors separately and driving them in parallel relation, a differential mechanism is no more required and the vehicle can be run by using all wheels.

Further, since the hydraulic motor is small and light, it can be built even in the wheel.

Furthermore, the present invention makes it possible to obtain all wheel steering. Moreover. steering of 45 to 90 degrees is available.

Claims

WHAT IS CLAIMED IS:

1. A power transmission system of vehicles comprising wheels: fluid pressure motors each connected to each of said wheels: fluid pipings for connecting said fluid motors in parallel relation; and main fluid pressure circuits each connected to the corresponding fluid Piping. --

2. A power transmission system of vehicles comprising wheels: fluid pressure motors each donnected to each of said wheels; fluid pipings for connecting said fluid pressure motors in parallel relation; main fluid pressure circuits each connected to the corresponding fluid piping; and means mounted directly or indirectly, to said wheels and acting on the wheels to prevent.

directly or indirectly, the rotation thereof by mechanical pressure such as a spring, by rendering a counter force with a fluid pressure cylinder such as hydraulic pressure by a fluid pressure from said main fluid Pressure circuit, braking being not acted on said wheels while the fluid pressure is present, but braking being acted on said wheels while the fluid pressure is not present.

3. A power transmission system of vehicles as claimed in claim 1 or claim 2, wherein said fluid pressure motor is a hydraulic motor.

4. A power transmission system of vehicles as claimed in claim 1 or claim 2, wherein said fluid pressure motor is indirectly connected to said wheel by at least one piece of free joint.

5. A power transmission system of vehicles as claimed in claim 1 or claim 2, wherein said fluid pressure motor is built in said wheel and directly connected thereto.

6. A power transmission system of vehicles as claimed in claim 9 or claim 2. wherein said fluid pressure motor is an outer rotor type.

7. A power transmission system of vehicles as claimed in claim 6 wherein said fluid pressure motor comprises a non-circular inner stator having a long diameter and a short diameter, and a circular outer rotor inscribed in an end of the long diameter of said inner stator.

8. A power transmission system of vehicles as claimed in claim 7 wherein said inner stator of said fluid pressure motor is formed in an elliptical shape.

9. A power transmission system of vehicles as claimed in claim 1 or claim 2, wherein said fluid pressure motor chiefly comprises a gear wheel as a rotor with its gear Portion provided on anywhere other than the outer periphery thereof, and a stator including an idle gear for meshing with the gear portion of said rotor.

10. A power transmission system of vehicles as claimed in claim 1 or claim 2, wherein said fluid pressure motor is provided with a drain collection cover at a potion where a fluid such as oil leaks from, and said fluid piping is provided with a drain collection piping extending from a fluid tank of said main fluid pressure circuit to said collection cover.

11. A power transmission system of vehicles as claimed in claim 1 or claim 2, wherein ät least a part of said fluid piping is flexible.

12. A power transmission system of vehicles as claimed in claim 1 or claim 2, wherein said fluid piping is connected to said main fluid pressure circuit by a joint such as a coupler.

13. A power transmission system of vehicles as claimed in claim 1 or claim 2, wherein said fluid piping is provided to a tractor and said main fluid Pressure circuit is provided to a trailer.

14. A power transmission system for vehicles, the system being substantially as hereinbefore described with reference to the accompanying drawings.