Transmission

The present invention relates to an improve(12) AUSTRALIAN PATENT ABRIDGMENT (19) AU (11) AU-B1-35 305/78

<td> (54)</td><td> REGENERATIVE</td><td colspan="2"> HYDROSTATIC TRANSMISSION</td><td></td>

<td> (75)</td><td> VINCENT EARL</td><td> CARMAN</td><td></td><td></td>

<td> (21)</td><td> 35 305/78</td><td></td><td> 522 012 (22)</td><td> 20.4.78</td>

<td> (23)</td><td> 20.4.78</td><td></td><td> (24)</td><td> 20.4.77</td>

<td> (31)</td><td> 789197</td><td></td><td> (32) 20.4.77 (33)</td><td> US</td>

<td> (43)</td><td> 25.10.79</td><td></td><td> (44)</td><td> 13.5.82</td>

<td> (51)2</td><td> F15B 1/02</td><td> B60K 9/00</td><td> B60K 20/14</td><td></td>

<td> (74)</td><td> DM</td><td></td><td></td><td></td>

<td> (56)</td><td> 33055/78</td><td> 513 553</td><td> B60K 26/04, 41/22</td><td></td>

<td></td><td> 18190/76</td><td></td><td> F15B 1/02, B62D 63/02</td><td></td>

<td> (57)</td><td> Claim 1. An</td><td> hydrauli c</td><td> multi-speed, multi-torque</td><td></td>

transmission system for a wheeled vehicle for selectively storing energy normally lost in braking the vehicle and releasing the stored energy to aid in accelerating the vehicle, said system compri sing:

(a) an accumulator for hydraulically pressurizing a compressible gas and storing hydraulic fluid under the pressure of said gas;

(b) hydraulic pump means mechanically coupled to the wheels of said vehicle for being driven by said wheels, said pump means having an inlet and an outlet, the outlet of said pump means being selectively hydraulically connected to said accumulator for pumping hydraulic fluid into said accumulator to pressurize said gas in response to the driving of said pump means by said wheels to brake said vehicle;

.../2

Dl

16*3 *115/17/4

<img file="AU522012B2_D0001.tif" />

<img file="AU522012B2_D0002.tif" />

I .78 .77 .82 or ι ng e

171 a

n der h e d aid to to

../2 (d) (e) (f) hydraulic motor means mechanically coupled to the wheels of said vehicle for driving said wheels, said motor means having an inlet and an outlet, the inlet of said motor means being selectively hydraulically connected to said accumulator for receiving hydraulic fluid under pressure therefrom, said motor means comprising a plurality of fixed displacement hydraulic motors mechanically coupled to said vehicle wheels;

an engine mounted on said vehicle;

fixed displacement hydraulic pump means driven by said engine, said fixed displacement pump means having an inlet and an outlet, said outlet being connected to the inlet of said hydraulic motor means for supplying hydraulic fluid under pressure to said motor means; and selectively operable valve means interposed between the inlet of said motor means and the outlet of said engine-driven fixed displacement pump means for selectively directing the flow of hydraulic fluid under pressure from said fixed displacement pump means alternatively to any one or more of said plurality of fixed displacement hydraulic motors.

Appl:

Comp!

Prioj

Relal ’Name

VIA fr .Addrt

Actui

,.^ddr(

Compj ,··. The j ‘ “inclx

6*3 *115/17/5

<img file="AU522012B2_D0003.tif" />

open

The terms and expressions which have been employed in the foregoing abstract and specification are used therein

<img file="AU522012B2_D0004.tif" />

COMMONWEALTH OF AUSTRALIA

PATENTS ACT 1952

COMPLETE SPECIFICATION (Original)

FOR OFFICE USE

35305/⁷⁸

Class

Application Number:

Lodged:

Complete Specification Lodged :

Accepted :

Published:

<img file="AU522012B2_D0005.tif" />

Priority:

Related Art:

/

<img file="AU522012B2_D0006.tif" />

r v · t e « O O &lt; ' I - · - . , . , « Ο * * « '-•-Name of Applicant: VINCENT EARL CARMAN β « « c » c nr &lt;&lt;» a

,.Address of Applicant: ⁹⁵¹² 3.W. 47th Avenue, Portland, Oregon * 97219, United States of America β Λ » * t « »

C © «

Actual Inventor(s): VINCENT EARL CARMAN e o« to to » • as /'.Address for Service: DAVIES &amp; COLLISON, Patent Attorneys, _e 1 Little Collins Street, Melbourne, 3000.

a © tt tt a ” Complete specification for the invention entitled:

HYDRAULIC ENERGY STORAGE MULTI-SPEED TRANSMISSION to 9 to to to to » to to to .··. The following statement is a full description of this invention, ^e ’including the best method of performing it known to us

78.

<img file="AU522012B2_D0007.tif" />

Oregon

Ξ , , 3000.

J vention,

The present invention relates to an improvement in the invention described in my U.S. patent No. 3,903,696 entitled Hydraulic Energy Storage Transmission, issued September 9, 1975. The dis5 closure of such patent is incorporated herein in its entirety by this reference.

A major problem which is presented with systems which, store braking energy and convert it to drive power by hydraulic principles is that such systems

10.. require an hydraulic transmission comprising one or more hydraulic motors to be driven by the output from the brake energy accumulator and an engine-driven pump. For vehicular use such hydraulic transmission must of necessity be multi-speed and multi-torque in character, i.e. it must have a selectively variable ratio of output shaft speed and torque with respect to the speed and torque of the engine.

β co « β o to a a c &lt; rt » » rt β

OO «ft e o o *· « ο e&gt; rt o e· ο β o © » * » » rt

K- tt *.

<img file="AU522012B2_D0008.tif" />

» a « I» β * « Q 1 — la

<img file="AU522012B2_D0009.tif" />

73ts stems rom ump.

.e :t β β ο » β « 4 ν « ε i 9 Ο Ο

Λ « β « β © - Ο * &gt;. © 0

Such multi-speed and torque capability is conventionally accomplished with hydraulic transmissions by the utilization of variable displacement pumps and/or motors in the transmission. A problem however arises from the fact that such variable displacement pump and motor equipment is customarily of very low efficiency due co the swash plate, wobble plate or other type of mechanical volumetric variation apparatus- utilized within the equipment.

According to the present invention there is provided an hydraulic multi-speed, multi-torque transmission system for a wheeled vehicle for selectively storing energy normally lost in braking the vehicle and releasing the stored energy to aid in accelerating the vehicle, said system comprising:

(a) an accumulator for hydraulically pressurizing a compressible gas and storing hydraulic fluid under the pressure of said gas;

(b) hydraulic pump means mechanically coupled to the wheels of said vehicle for being driven by said wheels, said pump means having an inlet and an outlet, the outlet of said pump means being selectively hydraulically connected to said accumulator for pumping hydraulic fluid into said accumulator to pressurize said gas in response to the driving of said pump means by said wheels to brake said vehicle;

<img file="AU522012B2_D0010.tif" />

(e) fixed displacement hydraulic pump means &lt; , 10.

Λ «ί '· Ο Ο v a a

c ©

». ο β

ί» « *

20.

Ο ♦

3α (c) hydraulic motor means mechanically coupled to the wheels of said vehicle for driving said wheels, said motor means having an inlet and an outlet, the inlet of said motor means being selectively hydraulically connected to said accumulator for receiving hydraulic fluid under pressure therefrom, said motor means comprising a plurality of fixed displacement hydraulic motors mechanically coupled to said vehicle wheels;

Cd) an engine mounted on said vehicle;

Ce) fixed displacement hydraulic pump means driven by said engine _f said fixed displacement pump means having an inlet and an outlet, said outlet being connected to the inlet of said hydraulic motor means for supplying hydraulic fluid under pressure to said motor means; and

(.f) selectively operable valve means interposed between the inlet of said motor means and the outlet of said engine-driven fixed displacement pump means for selectively directing the flow of hydraulic fluid under pressure from said fixed displacement pump means alternatively to any one or more of said plurality of fixed dis

<img file="AU522012B2_D0011.tif" />

♦ hydraulic motor means Cc). comprise a plurality of fixed displacement hydraulic pump-motors capable of placement hydraulic motors .

A preferred embodiment wi.ll hereinafter be described with reference to the accompanying drawing which is a single figure and is a schematic diagram of an illustrative embodiment of the hydraulic energy storage and conversion transmission system of the present invention.

- 3a ·-

<img file="AU522012B2_D0012.tif" />

9,. A wheeled vehicle incorporating an hydraulic multi-speed, multi-torque transmission

Detailed Description of the Invention

The illustrative embodiment of the invention shown in the single figure is in a number of respects identical to that shown in my U.S. patent No. 3,903,696, incorporated herein by reference. Identical numbers are used herein to indicate the same parts with the same functions as described in said patent, with the exceptions noted below, and will therefore not be duplicated in detail here, the reader being directed to said patent for a fuller explanation.

To summarize the elements of the system, ah *

engine or prime mover 62 drives a fixed displacement pump 64 which receives hydraulic fluid 30 from a reservoir 28 through line 68 and discharges the fluid under pressure into line 66. The pressurized fluid flows selectively to fixed displacement pump-motors 24' and 24’’, such motors being mechanically coupled to the wheels 55 and 55' through wheel drive shaft 26. In the driving mode, operator-controlled valves V-^ and Vg selectively regulate the flow of pressurized fluid to the pump-motors to control the motion of the vehicle. Return flow of the fluid from the pump-motors to the reservoir is through normally open valves V2 and and line 52.

Reverse motion can be accomplished through any conventional gearbox (not shown) mechanically coupling the drive pump-motors 24’ and 24’’ to the wheels or, alternatively, by utilizing bi-directional fixed displacement pump-motors and appropriate associated reversing circuitry, for example of the general type shown in my co-pending U.S.

patent application Serial No. 765,951, filed February 7,

1977, incorporated herein by this reference. Moreover the fixed displacement pump 64 could alternatively be a pump-motor for starting the engine 62 with associated cir5 cuitry and controls of the type shown in my aforesaid copending patent application.

In response to the application of the vehicle brakes, one or both of valves V£ and close, causing one or both of the pump-motors 24' and 24'' to be driven as pumps by the wheels 55, 55' and shaft 26 so as to help brake the vehicle. In the braking mode, the pump-motors deliver pressurized fluid through line 34 to the accumulator 16 through port 20, causing fluid under pressure to enter the accumulator in which a compressible gas designated by the numeral 60 is captivated. The gas, under the influence of this increasing pressure is compressed and, subsequently, when either or both of the valves and Vg are opened in the driving mode, for example in response to operation of a foot throttle, and the corresponding valves V2 and

V4 are open, the gas forces the hydraulic fluid in the accumulator to flow from port 20 to the pump-motors alone or in conjunction with fluid from the pump 64 to accelerate or otherwise propel the vehicle. Conversely, when the control valves V and are closed, hydraulic fluid from the pump

64 is directed into the accumulator 16 and the energy is stored therein, together with any braking energy supplied from the pump-motors 24' and 24'', for later use in helping to accelerate or otherwise propel the vehicle.

The major differences, between the figure herein and that of the referenced U.S. patent No. 3,903,696, involves the pump-motors 24' and 24'' and the control valving and associated hydraulic circuitry therefor.

Rather than a single drive motor, the present invention utilizes multiple fixed displacement drive pump-motors 24' and 24'' both mechanically coupled to the wheel drive shaft 26 so as to deliver torque to the shaft or, alternatively, receive torque from the shaft 26. Pump-motor 24' is of a higher volumetric capacity per revolution and has a higher torque output for any given hydraulic input pressure than does the smaller pump-motor 24''. For illustrative purposes it will be assumed that pump-motor 24' has twice the volumetric capacity and torque output as does pump-motor 24'’.

In the driving mode, the inputs 40' and 40'' of the two pump-motors respectively are selectively connected with the pressurized output of the pump 64 and accumulator 16 through respective lines 100' and 100'' and valves Vj and V3, while the outputs 48' and 48'' of the drive pump-motors are connected through open valves V2 and V4 respectively to the line 50 leading to the input line 68 of the pump 64 and to the reservoir 28.

Alternatively, when either valves V2 and V4 are closed in response to the braking of the vehicle, fluid under pressure from the respective pump-motor outlet

48' or 48'' is directed to the accumulator 16 through a respective check valve 102' or 102'' and line 34. The check valves 102' and 102'' prevent cross-feed between the outputs of the two pump-motors 24' and 24'' in case ' only one of the pump-motors is being used for braking, for reasons to be described hereafter, and also prevent short-circuiting of the pump-motors in the driving mode by the high-pressure fluid from the pump 64 and accumulator 16. A check valve 104 in the output line 66 of o tt * « *

© « at ft ft ft » « β ft ft et ϋ w ft the engine-driven pump 64 prevents excessive back pressure against the pump 64 in the braking mode.

During the braking mode, the respective valves and are both closed in response to the deactivation of the vehicle accelerator, and the respective pump-motors 24’ and/or 24’’ draw their input fluid from reservoir line 106 through a respective check valve 108' or 108 ¹ ' . The check valves 108' and 108'' prevent short-circuit' j of the pump-motors when in the driving mode.

Valves Vj and V-^, the positions of which may be manually controlled but are preferably automatically respon sive to an operating parameter of the vehicle such as drive torque or the pressure of hydraulic fluid supplied to the drive motors, are capable of selectively varying the speed and torque ratios between the wheel drive shaft 26 and engine drive shaft 62b. In the embodiment illustrated in the figure, when the valves and V3 are both open (valves V2 and also being open since the brake is not applied), hydraulic fluid under pressure is directed to the inputs 4Q' and 40'' of both pump-motors simultaneously. This results in the delivery of maximum torque to the wheels 55 and 55' through the shaft 26, and provides the lowest speed ratio of the wheels to the engine drive shaft 62b. Such valve positions would be used, for example, in accelerating the vehicle initially from a standing start.

If the valve V3 is closed, leaving the valve Vj open, only the higher-torque, higher-volume motor 24' receives pressurized fluid, the smaller motor 24'' being permitted to recirculate fluid drawn through line 106.

In these positions of the valves Vj_ and Vj , assuming for simplicity the same engine speed and engine torque output as in the first case ^r ire both valves were open, and neglecting the effect jf the pressure in th&lt; ?umulator 16, the torque delivered to the wheels 55 and 55' would be only 2/3 of that delivered in the first case, but the speed ratio of the wheels to the engine drive shaft 62b would’b£ 1-1/2 times that of the first case.

If the valve Vf is closed and the valve opened, only the smaller drive motor 24¹¹ is fed with pressurized fluid and the larger motor 24' simply recirculates its fluid as did the motor 24'' in the previous paragraph. In these positions of the valves and V^, under the same assumptions as in the previous paragraph, only 1/3 of the torque previously delivered to the wheel drive shaft 26 in the first case is now delivered, but the ratio of wheel speed to engine drive shaft speed is now three times the ratio in the first case. These latter positions of the valves would normally be used, for example, at vehicle cruising speeds.

The coast mode of the transmission is achieved by the closure of both of valves and Vg, valves V₂ and V₄ remaining open for recirculation.

In the braking ruode, valves Vj and Vg are closed, but one or both of valves V₂ and are likewise closed so as to charge the accumulator 16 with hr.'kinu energy through line 34. Valves Vo and Vmay 1 2 '•.inuaihy controlled but are preferably automatically responsive to an appropriate operating parameter such as the degree of brake pedal force applied by the operator. For example at relatively high vehicle speed only minimal braking would be desired to retain control of the vehicle and prevent skidding. In such case, in response to light brake pedal pressure, valve V^ would be closed to charge the accumulator with the smaller pump-motor 74’’ while valve V2 is left open to permit pump-motor 2· recirculate. At higher brake pedal pressure, where _ nigher degree of braking can obviously be tolerated, valve V would be open while valve \I is closed, resulting in pump-motor 24’ providing twice the braking torque of the pump-motor 24'' and twice the storage of braking energy assuming the same distance of travel during braking Where a maximum degree of braking is indicated, both valves V2 and V^ would be closed resulting in three times the braking torque of pump-motor 24’' and three times the storage of braking energy.

The foregoing explanation of operating conditions of the transmission is summarized for convenience in the following table:

*115/17/4

Ui

16*3

<img file="AU522012B2_D0013.tif" />

condition

Valves C=closed O=open ^V1 c

c c

c c

^V2 c

V_q

C c

c c

c ^V4 c

c illustrates a three-speed ft ft ft ft · ft ft ft « ft ft ft * « «

C)&gt; ft ·&gt; ft ft

Maximum acceleration

Intermediate acceleration

Minimum acceleration

Coast

Minimum braking Intermediate braking Maximum braking

The above example transmission utilizing two fixed displacement pump-motors of differing volumetric and torque capacity. Three fixed displacement pump-motors of different volumetric and torque capacity, with comparable valving, would result in a seven-speed transmission, and so forth. Moreover it is not vital that the various multiple fixed displacement pump-motors be mechanically coupled to the same wheel or wheels of a vehicle, but can be coupled to different sets of wheels.

With the utilization of multiple fixed displacement pump-moto :s, and with the aforedescribed proper type of control valving, an extremely efficient multi-speed, multi-torque hydraulic transmission can be utilized with a hydraulic brakino energy storage and conversion system without suffering any of the severe efficiency drawbacks normally associated with variable speed, variable torque hydraulic transmission systems, since all variable displacement mechanisms, primarily responsible for inefficiency, are eliminated.

*115/17/5

<img file="AU522012B2_D0014.tif" />

The terms and expressions which have been employed in the foregoing abstract and specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.

c(? P *

• ( ft » &amp;

ft tt