CA1116047A - Power steering valve and method of making same - Google Patents
Power steering valve and method of making sameInfo
- Publication number
- CA1116047A CA1116047A CA324,148A CA324148A CA1116047A CA 1116047 A CA1116047 A CA 1116047A CA 324148 A CA324148 A CA 324148A CA 1116047 A CA1116047 A CA 1116047A
- Authority
- CA
- Canada
- Prior art keywords
- valve sleeve
- grooves
- groove
- valve
- axially extending
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000004519 manufacturing process Methods 0.000 title abstract description 4
- 238000005520 cutting process Methods 0.000 claims abstract description 44
- 239000000463 material Substances 0.000 claims abstract description 8
- 239000012530 fluid Substances 0.000 claims description 34
- 238000004891 communication Methods 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 12
- 230000004323 axial length Effects 0.000 claims description 7
- 230000001154 acute effect Effects 0.000 claims description 3
- 230000001276 controlling effect Effects 0.000 claims 2
- 239000002184 metal Substances 0.000 description 5
- 238000003754 machining Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- ZUXNHFFVQWADJL-UHFFFAOYSA-N 3,4,5-trimethoxy-n-(2-methoxyethyl)-n-(4-phenyl-1,3-thiazol-2-yl)benzamide Chemical compound N=1C(C=2C=CC=CC=2)=CSC=1N(CCOC)C(=O)C1=CC(OC)=C(OC)C(OC)=C1 ZUXNHFFVQWADJL-UHFFFAOYSA-N 0.000 description 1
- 241000905957 Channa melasoma Species 0.000 description 1
- 235000017276 Salvia Nutrition 0.000 description 1
- 241001072909 Salvia Species 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 229940081330 tena Drugs 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
- B62D5/08—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle characterised by type of steering valve used
- B62D5/083—Rotary valves
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
- B62D5/20—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application
- B62D5/22—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application for rack-and-pinion type
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Power Steering Mechanism (AREA)
- Multiple-Way Valves (AREA)
- Steering Controls (AREA)
Abstract
POWER STEERING VALVE AND METHOD OF MAKING THE SAME
ABSTRACT OF THE DISCLOSURE
An improved power steering valve has a cylindrical sleeve which circumscribes an inner valve member. The valve sleeve has relatively short inner grooves which extend in opposite directions from a central portion of the sleeve. Although the inner grooves can be sequentially formed with an end mill, a pair of the axially extending inner grooves are advantageously formed at the same time by simultaneously cutting away material from the inside of the valve sleeve with a pair of rotating end mills. When a pair of axially extending inner valve grooves are being formed by the use of two end mills, the end mills extend into the valve sleeve from opposite axial ends of the valve sleeve.
ABSTRACT OF THE DISCLOSURE
An improved power steering valve has a cylindrical sleeve which circumscribes an inner valve member. The valve sleeve has relatively short inner grooves which extend in opposite directions from a central portion of the sleeve. Although the inner grooves can be sequentially formed with an end mill, a pair of the axially extending inner grooves are advantageously formed at the same time by simultaneously cutting away material from the inside of the valve sleeve with a pair of rotating end mills. When a pair of axially extending inner valve grooves are being formed by the use of two end mills, the end mills extend into the valve sleeve from opposite axial ends of the valve sleeve.
Description
: ~ ; BACRGROU~D OF TH~ INVENTION ~ :
¦. ~his invention relates to a'new and improved power . ¦ steering-valve and more speci~ically to a valve sleeve having I , . . .
; ~ I relatiYely short internal grooves which may b~ formea by a .-. .. :, . :.,, . -~ , .
.rotating cutting tool, such as an end mill.
.: . ., - ':, It has been previously suggested that a plurality of axially e~tending in~ernal grooves could be sequentially formed in a hollow cylindrical valve sleeve by using a rotating cutting tool such as çnd mill. The en~ mill is usea to form long grooves which extend throughout most of the axial length of the valve sleeve~ Due to the relatively lon~ length of the axiall~ extending inner groovesr they must be formed . one at a time with a single end mill. A complete di sclosure .
.. ' ~
of this previously suggested manner of forming grooves in a valve sleeve with an end mill is set forth in Canadian Patent Application Serial No. 323,3~, filed March 13, 1979 by Richard W. Dymond and entitled "Power Steeringr Valve And Method of Making The Same" (Docket No. TRW(M)7257).
SUMMARY 0~ r~lE PRESENT INVENTION
The present invention provicles a power steering apparatus comprising hydraulic motor means for assisting in operation of a vehicle steering gear. The apparatus further comprises a housing having a plurality of passages connected in comm~mication with a source o fluid and the hydraulic motor means, and improved valve means disposed in the housing for use in controlling fluid 10w through the passage in the housing to thereby control operation of the hydraulic motor means. The valve means includes an inner valve member and a Yalve sleeve circumscribing the inner valve member. The hollow valYe sleeYe includes an array of outer grooves each which opens outwardly and extends around the sleeve.
The array of outer grooves includes a first outer groove disposed in a central portion of the valve sleeve and connected in 1uid communication with a first one of the passages on the housing, a second outer groove disposed to one axial side of the central portion of the valYe sleeYe and the first outer groo~e and connected in fluid communication wi-th a second one of said passages in the housing, and a third outer groove disposed to another axial side of the central portion of the valve sleeve and the first groove and connected in fluid communication with a third one of the passages in the housing. The valve sleeve further includes a plurality of axially extending grooves on the inside of the valYe sleeve. A first one of the plurality o axially extending grooves has a first end surface disposed in the central portion . . .
~3~
i47 of the valve sleeve adjacent to the first outer groove and a Eirst main section which extends axlally away from the first end surface in a first axial direction to a second end surface disposed to the one axial side of the central portion of the valve sleeve and adjacent to the second outer groove. A second one of the plurality of axially extending grooves has a third end surEace disposed in the central portion of the valve sleeve adjacent to the first outer yroove and a second main section which extends axially away from the third end surface in a second axial direction which is opposite from said first axial direction to a fourth end surface disposed to the other axial side of the central portion of the sleeve and adjacent to the third outer groove.
Due to the Eact that the internal grooves extend in opposite axial directions from a central portion of the valve sleeve, at least some of the internal grooves are axially offset relative to other internal grooves. Since each of the internal grooves extends in only one axial direction from a central portion of the valve sleeve~ the machining time required to form the groove is reduced.
A method for manufacturing the improved valve sleeve of the invention is provided. The method includes the steps of providing a hollow valve sleeve, rotating first and second cutting tools about their central axes, engaging the inside of the hollow valve sleeve with the outer end portions of the rotating cutting tools at locations spaced apart from axial end portions of the valve sleeve. The first and second axially extending grooves having closed end portions inside the valve sleeve are formed simul~aneously by moving the first and second rotating cutting tools and valve sleeve relative to each other while maintaining the rotating cutting tools in engagement with the inside of the valve sleeve. Subsequently, the valve sleeve and cutting tools are moved out of engagement with each other.
-2a-, . , - , . ~ . . , IL1161~9L7 ( Accordingly, it is an object oE this invention to provide a new and improved valve sleeve havin~ internal grooves which extend in opposite axial directions from a central portion of the valve sleeve.
Another object of this invention is to provide a new and improved method o~ forming a valve sleeve and wherein a pair . .
of rotating cutting tools are simultaneously utilized to forlQ ~:
a pair of axially extending grooves inside a valve sleeve. . .:. .
Another object of this invention is to provide a new and improved valve sleeve having an array oE annular grooves formed in the outside of the valve sleeve and axially .
extending grooves formed inside the valve sleeve and wherein one of the inner grooves extends axially in a first dLrection .
from a central portion of the array of annular grooves and another inner groove extends in the opposite direction from :
the cen~ral portion of the array of annular grooves~;
. . ' ~
BRIEF DESCRIPTION OF THE DRAWINGS
: ... . ~ . ".' . The foregoing and other objects and features of the ~.
.~ present.invention will become more apparent upon a consideration of the following description taken in connection -with the accompanying drawings wherein:
Fi~. l is a fragmenta~y sectional view o~ a rack and .
pinion power steering apparatus having a control valve . ¦assembly constructed in accordance with the present invention;
¦ Fig. 2 is an enlarged fragmentary view further lillustrating the construction of the valve assembly;
. .
. .
. : . . ~ ;
6~47 Fig. 3 is a still further enlaryed secti.onal view ¦illustrating a valve sleeve constructed in accordance with the present invention and the relat:ionship hetween the valve sleeve and a pa.ir o~ rotating cutting tools which are u~ilized to simultaneously Eorm a pair of grooves in the val.ve sleeve;
and Fig. 4 is a schematic illustrati.on depicting the relationship between axially extending grooves Eormed in the ' valve sleeve and annula~ grooves formed on the outside of the valve sleeve, the valve sleeve being shown in a laid out plan view. , '.' ~ " , .. DESCRIPTION OF SPECIFIC PRE~RED. .
.EMBODIMEN'rS OF THE IN~ENTION :
A power steering~apparatus 20 (see Fig. 1) is connected with a pair of steerable vehicle wheels in a known manner by ~ :
a pair of tie rods~ one of which is indicatéd at 22 in Fig.
, ....... . .
. 1. The power steering apparatus 20 includes a power steering motor 26 having a circular piston 28 disposed in a motor . , : ' : .
.. cylinder 30. The circular piston 2~ is fixedly connected with . generally cylindrical rack bar 32 upon which a longitudinally ~ .
. extenaing array oE rack gear teeth 34 are disposea. Opposite ends of the rack bar 32 are connected with the tie rods by .
ball joints. Accordingly, the tie rod 22 is connected with :
the rack bar 32 by a ball joint 36. :
A va]ve assembly 42 is provided to control the operation ~
of the power steering motor 26. The valve assembly 42 .
includes an input section 46 which is connected with a . rut~table vehicle steerin~ wheel ~not shown) and is integrally ... 4 .
. . ..
. ' I
: ~ "' '; '' ' :
~ormed with an inner valve member ~8. Upon rot;ltion oE the input section 46, the ~alve assembl~ ~2 directs Eluid under pressure from a conduit 50 to either a conduit 52 or a conduit 54 connected with the power steering motor 26. The other one of the two conduits 52 or 54 is exhausted to a arain or fluid return conduit 58 through the valve assembly ~2. ~he relatively high fluid pressure conducted to the power steering motor 26 results in movement of the piston 28 and rack gear 34 :
to effect turning movement of the vehicle wheels and rotation of a pinion gear 60.
The pinion gear 60 cooperates with the valve assembl~ 42 to return it to an unactuated condition when the steerable wheels have been turned to an extent correspondiny to the extent of rotation of the input section 46. I~ should be noted that although the rack bar is primarily moved under the influence of forces applied by the power steering motor 26, drive forces can also be transmitted directly to the rack bar by the pinion gear 60 in a known manner. Since the general construction and mode of operation o~ the power steerlng `
apparatus 20 is well known, it will not be further described herein to avoid prolixity of description.
The valve assembly 42 (see Fig~ 2) includes a generally cylindrical inner valve member 48 which is integrally ~ormed with the input section 46, A torsion spring or rod 66 connects the inner valve member 48 with the pinion gear 60 in such a manner as to enable the inner valve member 48 to rotate -through a limited distance before the pinion gear 60 is rotated. This limited rotation of the valve member 48 is effective to move the valve member relative to ~ housing 70 ~ , . . :~' ~- . 5 . . .
- ' ' ; . , ' ;.,`~ ; ' .
~ . , , . . ~ ~ ., 6~
and valve sleeve 72 Erom an ~nactuated condition to an actuatea condition Actuation of the v~Lve assembly 42 is e~fective to direct fl~lid pressure from a housin~ inlet Ipassage 76 connected with the conduit 50 to a housiny passage j77 connected in fluid communication with the motor conduit 154. At the same time, the motor conduit 52 is connected ~7ith ¦drain conduit through housing passages 82 and ~ This ¦results in the power steering motor being operated to turn the ¦steerable vehicle wheels.
When the valve assembly ~2 is in the unactuated condition, fluid from conduit 50 is conducted through the housing passage 76 to an annular groove 80 dispose~ in a central portion of the valve sleeve 72. The annular groove 80 is connected with a pair o~ longitudinally extending pressure chambers or passages (not shown) disposed between the inner valve member 48 and the valve sleeve 7~ by a pair of raaially extending passages (not shown).
When the valve assembly 42 is in the unactuated conditiont the fluid in the longitudinally extending pressure chambers flows to a pair of diametrically opposed longitudinally extending outlet chambers (not shown~ formed between the valve sleeve 72 and valve member 48. This fluid flow between the longitudinally extenaing inlet and outle~
chambers i5 conducted through a plurality of axially extending grooves 100, 102, 104, and 106 (see Fig. 4) formed in the one-piece valve sleeve 72. The grooves 100, 102, ]04, and 106 all have arcuate bottom surfaces which promo~es a laminar flow of fluid through the grooves~ The laminar fluid flow tends to ~reduce valve noise.
.' - .
~ ' .
The axially ext:entli.n-J grooves 102 and 106 are connected jwith an annular ~roove 11~ forrned on the outside o~ the valve ¦sleeve at one axi~l end portion oE the annular array oE
grooves by a pa;r o~ pa~sages 116 and 118 (see Fiys. 2 and 4).
I The annular groove 11~ is connected in fluid communication ¦with the motor conduit 54 through the housing passage 77.
¦ The axially extending inner grooves 100 and 104 are connected with an annular outer groove 122 by valve passages 124 and 126. The annular groove 122 is connected in fluid communication with the motor conduit. 52 through the housing .
passage 82. .
. Upon actuation oE the valve assembly 42 to e~fec~ a turn, the inner valve member 4~ restricts fluid flow from the . pressure chambers to the axially extending grooves 100 a~d . 104. At the same time, the inner valve member 48 increases : the fluid col~munication between the grooves 100 and 104 and .
the relatively low pressure fluid outlet chambers. :, . While the fluid flow to the grooves 100 and 104 from the ~ . power steering pump is being decreased, ~luid flow to the .. :' axially extending grooves 102 and 106 is being increased. The ' . axially extending passages 102 and 106 are,connected with an : . axially outer annular groove 114 formed on the valve sleeve,7~
by the passages 116 and.118. The annular groove 114 is ' ' : ., connected in ~luid communication with the motor conduit 54 .
through the housing passage 77. ~ .~ :
¦ The axially extending grooves 100 and 104 are connected with the annular groove 122 (Fig. 2) by passages 124 and 126. :
' This enables the low pressure fluid exhausted from the power steering motor 26 to be conducted ba-ck to drain. .
. ~:
. ~ ,, j During a turn in the opposite direction, the inner valve member 48 is rotated in the opposite direction relative to the valve sleeve 72. Therefore, the axially extending passages 100 and 104 are connected with the longitud:inally extending pressure chambers and the inlet fluid is conducted to the annular outer groove 122 through the valve passages 124 and 126 extending between the inner grooves 100 and 104 and the annular groove 122. The axially outer groove 122 is connected in ~luid communication with the motor conduit 52 through the housing passage 82. At this time, the motor conduit 54 is exhausted to the drain conduit 58 through the axially outer annular groove 114, axially extending inner grooves 104 and 106, and longitudinally extending outlet chambers formed between the valve member 48 and valve sleeve 72.
The manner in which the valve member 48 cooperates with the one-piece valve sleeve 72 is more Eully described in the aforementioned Canadian Patent Application Serial No. 323,344, Eiled March 13, 1979, by Richard W. Dymond and entitled "Power Steering Valve And ~ethod Of Making The Same" (Doclcet No.
TRW(M)7257). Since the manner in which the valve sleeve 72 and valve member cooperate during steering operations is well known to those skilled in the art, it will not be further described herein.
The inner grooves 100, 102, 104, and 106 have a relatively short axial extent. Thus, the axial grooves 100, 102, 104, and 106 each have an overall axial length which is equal to ,. .~ , ; . ~
ppro~imat~ly tl~10 tllircls oE th~ overall axial lengtll o the array oE annular grooves 80, 114, and 122 on the outside of the valve s]eeve 72.
The grooves 100 and 102 extend axially in a first direction from a cent~al portion 132 (see Fiy. 4) of the ~ne-piece valve sleeve 72 toward the annular groove 122 and ., the axial end surface 134 of the valve sleeve. Similarly, the inner grooves 102 and 106 extend in the opposite direc~ion from the central p~rtion 132 of the valve sleeve toward the ' ' opposite axial end surface 138 of the valve sleeve. By forming the grooves 100, 102, 104~ and 106 with relatively short axial lengths, the machining time required to form the grooves tends to be minimized. In addition, the structural rigidity oE the valve sleeve 72 tends to be enhanced~ , The axially extending grooves 100 and 104 have Llat semicircular axially inner end surfaces 142 and 144. ~The end surfaces 142 and 144 are disposed in the central portion of the valve sleeve 72 at a location generally radial~y inwardly , of the annular ou~er groove 80 (see Figs. 3 and 4). ~Thus~ the end surfaces 1~2 and 144 are located radially inwardly from an annular side surface 145 of the groove 80.
The grooves 100 and 104 have constant depth main sections, , 146 and 148 which extend axially outwardly toward the leEt (as, ' viewed in Fig. 3) or upwardly tas viewed in Fig. 4) to a , location ad~acent to the axially outer annular groove 122.
The main sections 146 and 148 extend parallel to each other and to a longitudinal central axis 152 of the valve sleeve 72. The constant depth main sections 146 and 148 of the . . , . . , .
.
., . " . . .. :: .
' grooves 100 and 104 have a generally semicircular crosssectional conEiguration in ~ plane which extends perpendicular to the longitudinal central axis 152 of the valve sleeve 72.
Main sections 146 and 14~ of the inner grooves 100 and 104 end at axially outer end surfaces 154 and 156 which are disposed adjacent to the axially outer end surface 134 of the one-piece valve sleeve 72. The end surfaces 15~ and 156 have an arcuately curving configuration and form a portion of a cylinder. The sloping end surfaces 154 and 156 are intersected by the valve passages 124 and 126 which extend between the axially extending inner grooves 100 and 104 and the annular outer groove 122. In accordance with the disclosure in the aforementioned Dymond Application Serial No. 323,344, fi]ed March 13, 1979 (Docket No. TRW(M)7257) the annular outer groove 122 is deeper than the annular inner groove 80. However, the central groove 80 has a greater axial extent so that the grooves 80 and 122 have the same crosssectional area to accommodate fluid flow.
The axially extending inner grooves 102 and 106 extend in the opposite direction from the central portion 132 as do the grooves 100 and 104 (see Fig. 4~. The inner grooves 102 and 106 have flat semicircular end surfaces 160 and 162 (see Figs.
¦. ~his invention relates to a'new and improved power . ¦ steering-valve and more speci~ically to a valve sleeve having I , . . .
; ~ I relatiYely short internal grooves which may b~ formea by a .-. .. :, . :.,, . -~ , .
.rotating cutting tool, such as an end mill.
.: . ., - ':, It has been previously suggested that a plurality of axially e~tending in~ernal grooves could be sequentially formed in a hollow cylindrical valve sleeve by using a rotating cutting tool such as çnd mill. The en~ mill is usea to form long grooves which extend throughout most of the axial length of the valve sleeve~ Due to the relatively lon~ length of the axiall~ extending inner groovesr they must be formed . one at a time with a single end mill. A complete di sclosure .
.. ' ~
of this previously suggested manner of forming grooves in a valve sleeve with an end mill is set forth in Canadian Patent Application Serial No. 323,3~, filed March 13, 1979 by Richard W. Dymond and entitled "Power Steeringr Valve And Method of Making The Same" (Docket No. TRW(M)7257).
SUMMARY 0~ r~lE PRESENT INVENTION
The present invention provicles a power steering apparatus comprising hydraulic motor means for assisting in operation of a vehicle steering gear. The apparatus further comprises a housing having a plurality of passages connected in comm~mication with a source o fluid and the hydraulic motor means, and improved valve means disposed in the housing for use in controlling fluid 10w through the passage in the housing to thereby control operation of the hydraulic motor means. The valve means includes an inner valve member and a Yalve sleeve circumscribing the inner valve member. The hollow valYe sleeYe includes an array of outer grooves each which opens outwardly and extends around the sleeve.
The array of outer grooves includes a first outer groove disposed in a central portion of the valve sleeve and connected in 1uid communication with a first one of the passages on the housing, a second outer groove disposed to one axial side of the central portion of the valYe sleeYe and the first outer groo~e and connected in fluid communication wi-th a second one of said passages in the housing, and a third outer groove disposed to another axial side of the central portion of the valve sleeve and the first groove and connected in fluid communication with a third one of the passages in the housing. The valve sleeve further includes a plurality of axially extending grooves on the inside of the valYe sleeve. A first one of the plurality o axially extending grooves has a first end surface disposed in the central portion . . .
~3~
i47 of the valve sleeve adjacent to the first outer groove and a Eirst main section which extends axlally away from the first end surface in a first axial direction to a second end surface disposed to the one axial side of the central portion of the valve sleeve and adjacent to the second outer groove. A second one of the plurality of axially extending grooves has a third end surEace disposed in the central portion of the valve sleeve adjacent to the first outer yroove and a second main section which extends axially away from the third end surface in a second axial direction which is opposite from said first axial direction to a fourth end surface disposed to the other axial side of the central portion of the sleeve and adjacent to the third outer groove.
Due to the Eact that the internal grooves extend in opposite axial directions from a central portion of the valve sleeve, at least some of the internal grooves are axially offset relative to other internal grooves. Since each of the internal grooves extends in only one axial direction from a central portion of the valve sleeve~ the machining time required to form the groove is reduced.
A method for manufacturing the improved valve sleeve of the invention is provided. The method includes the steps of providing a hollow valve sleeve, rotating first and second cutting tools about their central axes, engaging the inside of the hollow valve sleeve with the outer end portions of the rotating cutting tools at locations spaced apart from axial end portions of the valve sleeve. The first and second axially extending grooves having closed end portions inside the valve sleeve are formed simul~aneously by moving the first and second rotating cutting tools and valve sleeve relative to each other while maintaining the rotating cutting tools in engagement with the inside of the valve sleeve. Subsequently, the valve sleeve and cutting tools are moved out of engagement with each other.
-2a-, . , - , . ~ . . , IL1161~9L7 ( Accordingly, it is an object oE this invention to provide a new and improved valve sleeve havin~ internal grooves which extend in opposite axial directions from a central portion of the valve sleeve.
Another object of this invention is to provide a new and improved method o~ forming a valve sleeve and wherein a pair . .
of rotating cutting tools are simultaneously utilized to forlQ ~:
a pair of axially extending grooves inside a valve sleeve. . .:. .
Another object of this invention is to provide a new and improved valve sleeve having an array oE annular grooves formed in the outside of the valve sleeve and axially .
extending grooves formed inside the valve sleeve and wherein one of the inner grooves extends axially in a first dLrection .
from a central portion of the array of annular grooves and another inner groove extends in the opposite direction from :
the cen~ral portion of the array of annular grooves~;
. . ' ~
BRIEF DESCRIPTION OF THE DRAWINGS
: ... . ~ . ".' . The foregoing and other objects and features of the ~.
.~ present.invention will become more apparent upon a consideration of the following description taken in connection -with the accompanying drawings wherein:
Fi~. l is a fragmenta~y sectional view o~ a rack and .
pinion power steering apparatus having a control valve . ¦assembly constructed in accordance with the present invention;
¦ Fig. 2 is an enlarged fragmentary view further lillustrating the construction of the valve assembly;
. .
. .
. : . . ~ ;
6~47 Fig. 3 is a still further enlaryed secti.onal view ¦illustrating a valve sleeve constructed in accordance with the present invention and the relat:ionship hetween the valve sleeve and a pa.ir o~ rotating cutting tools which are u~ilized to simultaneously Eorm a pair of grooves in the val.ve sleeve;
and Fig. 4 is a schematic illustrati.on depicting the relationship between axially extending grooves Eormed in the ' valve sleeve and annula~ grooves formed on the outside of the valve sleeve, the valve sleeve being shown in a laid out plan view. , '.' ~ " , .. DESCRIPTION OF SPECIFIC PRE~RED. .
.EMBODIMEN'rS OF THE IN~ENTION :
A power steering~apparatus 20 (see Fig. 1) is connected with a pair of steerable vehicle wheels in a known manner by ~ :
a pair of tie rods~ one of which is indicatéd at 22 in Fig.
, ....... . .
. 1. The power steering apparatus 20 includes a power steering motor 26 having a circular piston 28 disposed in a motor . , : ' : .
.. cylinder 30. The circular piston 2~ is fixedly connected with . generally cylindrical rack bar 32 upon which a longitudinally ~ .
. extenaing array oE rack gear teeth 34 are disposea. Opposite ends of the rack bar 32 are connected with the tie rods by .
ball joints. Accordingly, the tie rod 22 is connected with :
the rack bar 32 by a ball joint 36. :
A va]ve assembly 42 is provided to control the operation ~
of the power steering motor 26. The valve assembly 42 .
includes an input section 46 which is connected with a . rut~table vehicle steerin~ wheel ~not shown) and is integrally ... 4 .
. . ..
. ' I
: ~ "' '; '' ' :
~ormed with an inner valve member ~8. Upon rot;ltion oE the input section 46, the ~alve assembl~ ~2 directs Eluid under pressure from a conduit 50 to either a conduit 52 or a conduit 54 connected with the power steering motor 26. The other one of the two conduits 52 or 54 is exhausted to a arain or fluid return conduit 58 through the valve assembly ~2. ~he relatively high fluid pressure conducted to the power steering motor 26 results in movement of the piston 28 and rack gear 34 :
to effect turning movement of the vehicle wheels and rotation of a pinion gear 60.
The pinion gear 60 cooperates with the valve assembl~ 42 to return it to an unactuated condition when the steerable wheels have been turned to an extent correspondiny to the extent of rotation of the input section 46. I~ should be noted that although the rack bar is primarily moved under the influence of forces applied by the power steering motor 26, drive forces can also be transmitted directly to the rack bar by the pinion gear 60 in a known manner. Since the general construction and mode of operation o~ the power steerlng `
apparatus 20 is well known, it will not be further described herein to avoid prolixity of description.
The valve assembly 42 (see Fig~ 2) includes a generally cylindrical inner valve member 48 which is integrally ~ormed with the input section 46, A torsion spring or rod 66 connects the inner valve member 48 with the pinion gear 60 in such a manner as to enable the inner valve member 48 to rotate -through a limited distance before the pinion gear 60 is rotated. This limited rotation of the valve member 48 is effective to move the valve member relative to ~ housing 70 ~ , . . :~' ~- . 5 . . .
- ' ' ; . , ' ;.,`~ ; ' .
~ . , , . . ~ ~ ., 6~
and valve sleeve 72 Erom an ~nactuated condition to an actuatea condition Actuation of the v~Lve assembly 42 is e~fective to direct fl~lid pressure from a housin~ inlet Ipassage 76 connected with the conduit 50 to a housiny passage j77 connected in fluid communication with the motor conduit 154. At the same time, the motor conduit 52 is connected ~7ith ¦drain conduit through housing passages 82 and ~ This ¦results in the power steering motor being operated to turn the ¦steerable vehicle wheels.
When the valve assembly ~2 is in the unactuated condition, fluid from conduit 50 is conducted through the housing passage 76 to an annular groove 80 dispose~ in a central portion of the valve sleeve 72. The annular groove 80 is connected with a pair o~ longitudinally extending pressure chambers or passages (not shown) disposed between the inner valve member 48 and the valve sleeve 7~ by a pair of raaially extending passages (not shown).
When the valve assembly 42 is in the unactuated conditiont the fluid in the longitudinally extending pressure chambers flows to a pair of diametrically opposed longitudinally extending outlet chambers (not shown~ formed between the valve sleeve 72 and valve member 48. This fluid flow between the longitudinally extenaing inlet and outle~
chambers i5 conducted through a plurality of axially extending grooves 100, 102, 104, and 106 (see Fig. 4) formed in the one-piece valve sleeve 72. The grooves 100, 102, ]04, and 106 all have arcuate bottom surfaces which promo~es a laminar flow of fluid through the grooves~ The laminar fluid flow tends to ~reduce valve noise.
.' - .
~ ' .
The axially ext:entli.n-J grooves 102 and 106 are connected jwith an annular ~roove 11~ forrned on the outside o~ the valve ¦sleeve at one axi~l end portion oE the annular array oE
grooves by a pa;r o~ pa~sages 116 and 118 (see Fiys. 2 and 4).
I The annular groove 11~ is connected in fluid communication ¦with the motor conduit 54 through the housing passage 77.
¦ The axially extending inner grooves 100 and 104 are connected with an annular outer groove 122 by valve passages 124 and 126. The annular groove 122 is connected in fluid communication with the motor conduit. 52 through the housing .
passage 82. .
. Upon actuation oE the valve assembly 42 to e~fec~ a turn, the inner valve member 4~ restricts fluid flow from the . pressure chambers to the axially extending grooves 100 a~d . 104. At the same time, the inner valve member 48 increases : the fluid col~munication between the grooves 100 and 104 and .
the relatively low pressure fluid outlet chambers. :, . While the fluid flow to the grooves 100 and 104 from the ~ . power steering pump is being decreased, ~luid flow to the .. :' axially extending grooves 102 and 106 is being increased. The ' . axially extending passages 102 and 106 are,connected with an : . axially outer annular groove 114 formed on the valve sleeve,7~
by the passages 116 and.118. The annular groove 114 is ' ' : ., connected in ~luid communication with the motor conduit 54 .
through the housing passage 77. ~ .~ :
¦ The axially extending grooves 100 and 104 are connected with the annular groove 122 (Fig. 2) by passages 124 and 126. :
' This enables the low pressure fluid exhausted from the power steering motor 26 to be conducted ba-ck to drain. .
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. ~ ,, j During a turn in the opposite direction, the inner valve member 48 is rotated in the opposite direction relative to the valve sleeve 72. Therefore, the axially extending passages 100 and 104 are connected with the longitud:inally extending pressure chambers and the inlet fluid is conducted to the annular outer groove 122 through the valve passages 124 and 126 extending between the inner grooves 100 and 104 and the annular groove 122. The axially outer groove 122 is connected in ~luid communication with the motor conduit 52 through the housing passage 82. At this time, the motor conduit 54 is exhausted to the drain conduit 58 through the axially outer annular groove 114, axially extending inner grooves 104 and 106, and longitudinally extending outlet chambers formed between the valve member 48 and valve sleeve 72.
The manner in which the valve member 48 cooperates with the one-piece valve sleeve 72 is more Eully described in the aforementioned Canadian Patent Application Serial No. 323,344, Eiled March 13, 1979, by Richard W. Dymond and entitled "Power Steering Valve And ~ethod Of Making The Same" (Doclcet No.
TRW(M)7257). Since the manner in which the valve sleeve 72 and valve member cooperate during steering operations is well known to those skilled in the art, it will not be further described herein.
The inner grooves 100, 102, 104, and 106 have a relatively short axial extent. Thus, the axial grooves 100, 102, 104, and 106 each have an overall axial length which is equal to ,. .~ , ; . ~
ppro~imat~ly tl~10 tllircls oE th~ overall axial lengtll o the array oE annular grooves 80, 114, and 122 on the outside of the valve s]eeve 72.
The grooves 100 and 102 extend axially in a first direction from a cent~al portion 132 (see Fiy. 4) of the ~ne-piece valve sleeve 72 toward the annular groove 122 and ., the axial end surface 134 of the valve sleeve. Similarly, the inner grooves 102 and 106 extend in the opposite direc~ion from the central p~rtion 132 of the valve sleeve toward the ' ' opposite axial end surface 138 of the valve sleeve. By forming the grooves 100, 102, 104~ and 106 with relatively short axial lengths, the machining time required to form the grooves tends to be minimized. In addition, the structural rigidity oE the valve sleeve 72 tends to be enhanced~ , The axially extending grooves 100 and 104 have Llat semicircular axially inner end surfaces 142 and 144. ~The end surfaces 142 and 144 are disposed in the central portion of the valve sleeve 72 at a location generally radial~y inwardly , of the annular ou~er groove 80 (see Figs. 3 and 4). ~Thus~ the end surfaces 1~2 and 144 are located radially inwardly from an annular side surface 145 of the groove 80.
The grooves 100 and 104 have constant depth main sections, , 146 and 148 which extend axially outwardly toward the leEt (as, ' viewed in Fig. 3) or upwardly tas viewed in Fig. 4) to a , location ad~acent to the axially outer annular groove 122.
The main sections 146 and 148 extend parallel to each other and to a longitudinal central axis 152 of the valve sleeve 72. The constant depth main sections 146 and 148 of the . . , . . , .
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' grooves 100 and 104 have a generally semicircular crosssectional conEiguration in ~ plane which extends perpendicular to the longitudinal central axis 152 of the valve sleeve 72.
Main sections 146 and 14~ of the inner grooves 100 and 104 end at axially outer end surfaces 154 and 156 which are disposed adjacent to the axially outer end surface 134 of the one-piece valve sleeve 72. The end surfaces 15~ and 156 have an arcuately curving configuration and form a portion of a cylinder. The sloping end surfaces 154 and 156 are intersected by the valve passages 124 and 126 which extend between the axially extending inner grooves 100 and 104 and the annular outer groove 122. In accordance with the disclosure in the aforementioned Dymond Application Serial No. 323,344, fi]ed March 13, 1979 (Docket No. TRW(M)7257) the annular outer groove 122 is deeper than the annular inner groove 80. However, the central groove 80 has a greater axial extent so that the grooves 80 and 122 have the same crosssectional area to accommodate fluid flow.
The axially extending inner grooves 102 and 106 extend in the opposite direction from the central portion 132 as do the grooves 100 and 104 (see Fig. 4~. The inner grooves 102 and 106 have flat semicircular end surfaces 160 and 162 (see Figs.
2 and 4) which are disposed in the central portion 132 of the valve sleeve 72 at a location generally inwardly of the central annular outer groove 80. Thus, the end surfaces 160 and 162 are located radially inwardly from an annular side surface 163 of the grOQve 80.
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The grooves 102 ancl l.0~ have axlally extendi.ng constant Idepth mc~ln sect:ions 164 and :l66. The main sections 164 and ¦166 extend axially out~ardly from the central portion 132 in a directi.on opposite from the grooves 100 and 10~, that is in a downward direction as vie~ed in Fig. 4 or toward the left as viewed in Fig. 3. The main sections 164 and 166 oE the grooves 102 and 106 extend parallel to each other and to the longitudi.nal central axis 152 of the valve sleeve 72. The main sections 164 and 166 of the grooves 102 and 106 have the same semicircular cross sectional conEiguration as the main . sections 146 and 1~8 of the grooves 100 and 104. .
: The constant depth main sections 164 and 166 o~ the . grooves 102 and lD6 terminate at axiall.y sloping end surfaces . 170 and 172 (see Figs. 2 and 4) which are disposed generally radially inwardly of the axially outer annular groove 11~
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The end surfaces 170 and 172 slope axially outwardly toward . the outer end surface 138 of the valve sleeve ~72 and have a arcuately curving configuration corresponding to a portion of a cylinder. The valve passages 116 and 118 extend between the .
end surfaces 170 and 172 of the axially extending inner . . ' ' '. , , . .
. grooves 102 and 106 and the annular outer groove 114. :
It should be noted that the annular outer groove 114 has a sloping bottom surface which enables it to be relatively ~
deep and to have a relatively short axial extent, compared to .
the annuIar center groove ~0, while still havin~ the same . crosssectional area for handling fluid flo~ as the annular groove. By providiny both oE the axially outer annular ¦grooves 114 and 122 with sloping bottom surfaces which are .,' ~. : :, .'' : , ' :. .
~djac~nt to the .510ping bottorn sur~clces o~ t.he associated axially eY.tending inner ~rooves, the overall axial extent o~
the valve sleeve 72 tends to be rninimized.
In accordance with a feature of the present inventi~n, the relatively short axial length of the inner grooves 100, 102, 104, and 106 enables a pair oE rotatiny cutting tool~, which have been indicated in dashed lines at 178 and 180 in Fig. 3, to be utilized to simultaneously form a pair o~ inner grooves. Although other types oE rotatable cutting tools could be used, the cutting tools 178 and 180 are end mills.
The end mill 178 has a circular end Eace 184 and a cylindrical side portion 186. The end mill 180 is identical to the end mill 178 and has a circular end face and a ~ylindri~al side portion.
The end mills 178 and 1~0 are simultaneously rotated about their longitudinally extending central axes by suitable drive members or chucks (not shown~. ~lthough many difEerent types of end mills could be utilized, one suitable type o end mill is of the center cutting t~pe manu~actured by Green~ield Tap & Die d Green~ield, Massachusetts. ~his particular end mill has cutting flutes at the circular end face 184 and cutting ~lutes extending along the side portion 186 so that material can ~e cut away with either the end face 184 or the side portion 186 oE the end mill.
When the axially extending grooves 100, 102, 104, and 106 are to be formed in the metal valve sleeve 72, the valve sleeve is firmly mounted in an indexible holder or chuck (not shown). The chuck grips the central portion of the valve sleeve 72 and leaves opposite ends of the valve sleeve open.
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rhe chuck holds tlle valve sleeve 72 with tlle central axis 152 oE the valve sleeve co;ncident ~ith the axis o~ rotation of the chuck. The chuck is accurately indexible to t~o positions spaced 180~ apart with each o~ the positions corresponding to a location in which t~70 of the axially extending grooves are simultaneously forMed.
In order to simultaneously form the two axially extendinc) grooves 100 and 102, the end mills 178 and 180 are inserted .
into opposite axial open ends of the valve sleeve 72. The leading or axially outer end portions oE the end mills 178 and 180 are moved into engagetnent with the valve sleeve 72 at locations adjacent.to opposike axial ends of the valve sleeve. This results in the simultaneously forming of the axially sloping side surfaces 154 ancl 170 with the side portions of the.rotating end mills 178 and 1800 It should be noted that the longitudinal central axes o~ the two end mills .
intersect the longitudinal central axis 152 of the valve .
sleeve 72 and extend at the same acute angle relative to the longitudinal central axis 152 of the valve sleeve 72. .
Therefore, the simultaneously formed end surfaces 154 and 170 of the axially ex-tending grooves 100 and 102 slope inwardly toward the axis 152 in a direction toward the opposite axial end suraces 134 and 138 of the valve sleeve 72. It should also be noted that the sloping end surface 154 of the axially extending groove 100 is disposed radially inwardly of the annular outer groove 122 while the axially sloping end surface 170 of the inner groove 102 is disposed radiall~ inwardly of the annular groove 114.
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In order to simultaneous.l.y Eorrn tlle eon~.tarlt depth main ¦sections 146 ~nd 1~ of the two yroove~ 100 and :lO2, tile rotating end mi.lls 178 and 180 are simultaneously moved into the valve sleeve 72 along paths extending paral].el to the longituclinal central axis 152 of the valve sleeve. As the end mill 178 moves axially inwardly into the valve sleeve 72, the circular end face 184 oE the end mill cuts away the material on the inside of the valve sleeve to form the s~raight groove 100. At the same time, the rotating circular end ace oE the . end mill 180 is cutting away material on the inside of the valve sleeve 72 to form the straight groove 102.
. Since the main body portions 146 and 164 of the grooves lnO and 102 are simultaneously formed by the rotating circular end faces of the end mills 178 and 180 as they move axially into the valve sleeve 72, the constant depth main sections o the grooves 100 and 102 have the same semicircular cross sectional configurations in a plane extending perpendicular to .
the longitudinal central axis 152 of the valve sleeve 72.
- This arcuate cross sectional configuration promo~es a ~uiet . laminar flow o fluid through the grooves during operation of the valve assembly.~
The inward movement oE the end mill 178 into the one-piece valve sleeve 72 is terminated at the slop.ing end sur~ace 142. Simultaneously therewith, the axially inward movement of the rotating end mill 180 is terminated at the sloping end surface 160. The sloping end surEaces 142 and 160 are formed b~ the circular end Eaces oE the end mills 178 and 180 at locations on opposite axial sides oE the central portion 132 of the valve sleeve 72.
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~ lhen the end mills 1.7~ ~nd 180 re~ch their end o~ stroke positions shown in dashed :Lines in Fig. 3, the end mil]s do not en~age each other or the opposite axial ends of the valve-s].eevè 72. This is due to the ~act that the grooves 100 and 102 have a relatively short axial extent. IE the groove 100 was substantially longer, the end mill 178 ~Jould nick the axially outer end of the valve sleeve 72. It should also be noted that the axes about which the end mills are rotated both intersec~ the central axis 152 of the valve s.teeve 72.
Therefore, i the end mills 178 and 180 were moved further into the valve sleeve 72, there would be a tendenc~ for the end mills to engage each other.
Once the grooves 100 and 102 have been .simultaneously formed in the manner previously explained, the ro-tating end mills 178 and 180 will be disengaged from the grooves ana withdrawn from the valve sleeve 72~ The valve sleeve is then rotated about its central axis through an arcuate distance of 180~ to position the valve sleeve 72 or the ~ormation of the-grooves 104 and 106. The groove I04 is formed by the end mill 178 simultaneously with the formation of the yroove 106 by the end mill 180. It should be noted that the graove 104 will De identical to the groove 100 and that the groove 106 will be identical to the groove 102. It should also be noted t'nat the only difference in the grooves 100 and 104 and grooves 102 and 106 is that they extend .in opposite directions from the central portion 132 of the valve sleeve 72.
Although the grooves 100 and 102 have been described herein as being formea by moving the rotating cutting tools 178 and 180 simultaneously inwardly toward the central portion . . ' , , . ,, ' . ; , tlle valve sleeve, ;t i5 contemplated tl~at the groo-~es 100 and 102 could be simultaneouE;ly forrned by moviny ~he valve sleeve 72 relative to the ro~ating cuttiny too:Ls 17~ and 1~0.
I this was done, the circular end face o~ one o the cuttiny tools would be utilized to cut away mekal to forrn one of the axially extending inner grooves while the side portion of khe other rotating cutting tool would be utilized to s;multaneously cut away metal and form the other axially extending inner groove. I the grooves were to be formed in this manner, one o the cutting tools would be moved into engagement with the valve sleeve 72 at a location where an axially outer end surEace of a groove is to be formed while the other cutting tool would be moved into engagement with valve sleeve at a location where an axially inner end sur~ace of a groove is to be ormed. The valve sleeve would then be moved axially relative to the rotating cuttiny tools to effect -the simultaneous formation of the two grooves~
If the grooves 100 and 102 are to be form~d in this manner, the circular end face 184 o~ the rotating cutting tool 178 may be utilized to cut away metal to form the groove 100.
The side portion of the rotating cuttiny tool 180 coul.d be utilized to cut away metal to orm the groove 102. Thus~ the leading end portion of the end mill 178 would be moved into engagement with the valve sleeve 72 to form the end surface 15~ in the manner previously explained. Simultaneously therewith, the leading or axially outer end portion of the rotating cu~ting tool 180 would engage the central portion 132 of the valve sleeve to form the end surace 160 of the axially ¦exten ng inner groove l02.
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" .::` :' Once the two end mills have forlned the axiaLly outer end surEace 154 and the axially inner surfc~ce 160, the valve sleeve would be moved axially relative to the rotating end mills. Thus, the valve sleeve ~70uld be movecl axially toward the right (as viewed in Fig. 3) to enable the outer face 1~4 of the end mill 17~ to form the constant depth main section .
146 of the groove 100. This axial movement oE the valve sleeve would also cause the side port;on oE the rotating end mill 180 to cut away the main portion 16~ of the axially .
extending inner ~roove 102. The axial movement of the valve sleeve 72 would be stopped when the end mil]. 178 had been inserted far enough into the valve sleeve 72 to form the en~
face 142 and the end mill 180 and had been withdLawD from the valve sleeve 72 through a sufficient distance to Eorm the end surface 170. . ; -In view of the foregoing remarks it is apparent that the present invention provides a new and improved one-p1ece valve sleeve 72 and method by which the valve sleeve is formed. The hollow cylindrical`valve sleeve 72 has a plurality of .
relatively short axially extending internal grooves 100, 102, 104, and 106. The internal grooves 100 and 104 ex-tena in one axial direction from a central portion 132 of the valve sleeve while the grooves 102 and 106 extend in the opposite axial direction. ~herefore, at least some of the internal grooves are axially offset relative to other internal grooves. Since -each o the internal grooves 100, 102, 104, and 106 extends in only one axial direction from a central portion 132 oE the : -valve sleeve, the machining time required to form each of the grooves is xeduced.
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In accorcl~lnce ~1.ith another fe~ture o~ the present invention, it is possible to sirnultaneously ~orm two of the short axially extending grooves by using a pair o~ rotary cutting tools such as end mill.s 178 and 180. When the a%ially extending grooves 100, 102, 104, and 106 are to be formed in this manner, the end mills 178 and 180 are inserted into opposite axial. ends of the valve sleeve. Upon the occurrence of relative movement between the end mills 178 and 180 and the valve sleeve 72, the end mills simultaneously cut away metal to form a pair of axially ext,ending grooves in the one-piece valve sleeve. However, it is contemplated that the grooves .
100, 102, 104, and 106 could be sequentially formed one at a time th a singIe ~nd mill if desired.
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The grooves 102 ancl l.0~ have axlally extendi.ng constant Idepth mc~ln sect:ions 164 and :l66. The main sections 164 and ¦166 extend axially out~ardly from the central portion 132 in a directi.on opposite from the grooves 100 and 10~, that is in a downward direction as vie~ed in Fig. 4 or toward the left as viewed in Fig. 3. The main sections 164 and 166 oE the grooves 102 and 106 extend parallel to each other and to the longitudi.nal central axis 152 of the valve sleeve 72. The main sections 164 and 166 of the grooves 102 and 106 have the same semicircular cross sectional conEiguration as the main . sections 146 and 1~8 of the grooves 100 and 104. .
: The constant depth main sections 164 and 166 o~ the . grooves 102 and lD6 terminate at axiall.y sloping end surfaces . 170 and 172 (see Figs. 2 and 4) which are disposed generally radially inwardly of the axially outer annular groove 11~
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The end surfaces 170 and 172 slope axially outwardly toward . the outer end surface 138 of the valve sleeve ~72 and have a arcuately curving configuration corresponding to a portion of a cylinder. The valve passages 116 and 118 extend between the .
end surfaces 170 and 172 of the axially extending inner . . ' ' '. , , . .
. grooves 102 and 106 and the annular outer groove 114. :
It should be noted that the annular outer groove 114 has a sloping bottom surface which enables it to be relatively ~
deep and to have a relatively short axial extent, compared to .
the annuIar center groove ~0, while still havin~ the same . crosssectional area for handling fluid flo~ as the annular groove. By providiny both oE the axially outer annular ¦grooves 114 and 122 with sloping bottom surfaces which are .,' ~. : :, .'' : , ' :. .
~djac~nt to the .510ping bottorn sur~clces o~ t.he associated axially eY.tending inner ~rooves, the overall axial extent o~
the valve sleeve 72 tends to be rninimized.
In accordance with a feature of the present inventi~n, the relatively short axial length of the inner grooves 100, 102, 104, and 106 enables a pair oE rotatiny cutting tool~, which have been indicated in dashed lines at 178 and 180 in Fig. 3, to be utilized to simultaneously form a pair o~ inner grooves. Although other types oE rotatable cutting tools could be used, the cutting tools 178 and 180 are end mills.
The end mill 178 has a circular end Eace 184 and a cylindrical side portion 186. The end mill 180 is identical to the end mill 178 and has a circular end face and a ~ylindri~al side portion.
The end mills 178 and 1~0 are simultaneously rotated about their longitudinally extending central axes by suitable drive members or chucks (not shown~. ~lthough many difEerent types of end mills could be utilized, one suitable type o end mill is of the center cutting t~pe manu~actured by Green~ield Tap & Die d Green~ield, Massachusetts. ~his particular end mill has cutting flutes at the circular end face 184 and cutting ~lutes extending along the side portion 186 so that material can ~e cut away with either the end face 184 or the side portion 186 oE the end mill.
When the axially extending grooves 100, 102, 104, and 106 are to be formed in the metal valve sleeve 72, the valve sleeve is firmly mounted in an indexible holder or chuck (not shown). The chuck grips the central portion of the valve sleeve 72 and leaves opposite ends of the valve sleeve open.
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rhe chuck holds tlle valve sleeve 72 with tlle central axis 152 oE the valve sleeve co;ncident ~ith the axis o~ rotation of the chuck. The chuck is accurately indexible to t~o positions spaced 180~ apart with each o~ the positions corresponding to a location in which t~70 of the axially extending grooves are simultaneously forMed.
In order to simultaneously form the two axially extendinc) grooves 100 and 102, the end mills 178 and 180 are inserted .
into opposite axial open ends of the valve sleeve 72. The leading or axially outer end portions oE the end mills 178 and 180 are moved into engagetnent with the valve sleeve 72 at locations adjacent.to opposike axial ends of the valve sleeve. This results in the simultaneously forming of the axially sloping side surfaces 154 ancl 170 with the side portions of the.rotating end mills 178 and 1800 It should be noted that the longitudinal central axes o~ the two end mills .
intersect the longitudinal central axis 152 of the valve .
sleeve 72 and extend at the same acute angle relative to the longitudinal central axis 152 of the valve sleeve 72. .
Therefore, the simultaneously formed end surfaces 154 and 170 of the axially ex-tending grooves 100 and 102 slope inwardly toward the axis 152 in a direction toward the opposite axial end suraces 134 and 138 of the valve sleeve 72. It should also be noted that the sloping end surface 154 of the axially extending groove 100 is disposed radially inwardly of the annular outer groove 122 while the axially sloping end surface 170 of the inner groove 102 is disposed radiall~ inwardly of the annular groove 114.
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In order to simultaneous.l.y Eorrn tlle eon~.tarlt depth main ¦sections 146 ~nd 1~ of the two yroove~ 100 and :lO2, tile rotating end mi.lls 178 and 180 are simultaneously moved into the valve sleeve 72 along paths extending paral].el to the longituclinal central axis 152 of the valve sleeve. As the end mill 178 moves axially inwardly into the valve sleeve 72, the circular end face 184 oE the end mill cuts away the material on the inside of the valve sleeve to form the s~raight groove 100. At the same time, the rotating circular end ace oE the . end mill 180 is cutting away material on the inside of the valve sleeve 72 to form the straight groove 102.
. Since the main body portions 146 and 164 of the grooves lnO and 102 are simultaneously formed by the rotating circular end faces of the end mills 178 and 180 as they move axially into the valve sleeve 72, the constant depth main sections o the grooves 100 and 102 have the same semicircular cross sectional configurations in a plane extending perpendicular to .
the longitudinal central axis 152 of the valve sleeve 72.
- This arcuate cross sectional configuration promo~es a ~uiet . laminar flow o fluid through the grooves during operation of the valve assembly.~
The inward movement oE the end mill 178 into the one-piece valve sleeve 72 is terminated at the slop.ing end sur~ace 142. Simultaneously therewith, the axially inward movement of the rotating end mill 180 is terminated at the sloping end surface 160. The sloping end surEaces 142 and 160 are formed b~ the circular end Eaces oE the end mills 178 and 180 at locations on opposite axial sides oE the central portion 132 of the valve sleeve 72.
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~ lhen the end mills 1.7~ ~nd 180 re~ch their end o~ stroke positions shown in dashed :Lines in Fig. 3, the end mil]s do not en~age each other or the opposite axial ends of the valve-s].eevè 72. This is due to the ~act that the grooves 100 and 102 have a relatively short axial extent. IE the groove 100 was substantially longer, the end mill 178 ~Jould nick the axially outer end of the valve sleeve 72. It should also be noted that the axes about which the end mills are rotated both intersec~ the central axis 152 of the valve s.teeve 72.
Therefore, i the end mills 178 and 180 were moved further into the valve sleeve 72, there would be a tendenc~ for the end mills to engage each other.
Once the grooves 100 and 102 have been .simultaneously formed in the manner previously explained, the ro-tating end mills 178 and 180 will be disengaged from the grooves ana withdrawn from the valve sleeve 72~ The valve sleeve is then rotated about its central axis through an arcuate distance of 180~ to position the valve sleeve 72 or the ~ormation of the-grooves 104 and 106. The groove I04 is formed by the end mill 178 simultaneously with the formation of the yroove 106 by the end mill 180. It should be noted that the graove 104 will De identical to the groove 100 and that the groove 106 will be identical to the groove 102. It should also be noted t'nat the only difference in the grooves 100 and 104 and grooves 102 and 106 is that they extend .in opposite directions from the central portion 132 of the valve sleeve 72.
Although the grooves 100 and 102 have been described herein as being formea by moving the rotating cutting tools 178 and 180 simultaneously inwardly toward the central portion . . ' , , . ,, ' . ; , tlle valve sleeve, ;t i5 contemplated tl~at the groo-~es 100 and 102 could be simultaneouE;ly forrned by moviny ~he valve sleeve 72 relative to the ro~ating cuttiny too:Ls 17~ and 1~0.
I this was done, the circular end face o~ one o the cuttiny tools would be utilized to cut away mekal to forrn one of the axially extending inner grooves while the side portion of khe other rotating cutting tool would be utilized to s;multaneously cut away metal and form the other axially extending inner groove. I the grooves were to be formed in this manner, one o the cutting tools would be moved into engagement with the valve sleeve 72 at a location where an axially outer end surEace of a groove is to be formed while the other cutting tool would be moved into engagement with valve sleeve at a location where an axially inner end sur~ace of a groove is to be ormed. The valve sleeve would then be moved axially relative to the rotating cuttiny tools to effect -the simultaneous formation of the two grooves~
If the grooves 100 and 102 are to be form~d in this manner, the circular end face 184 o~ the rotating cutting tool 178 may be utilized to cut away metal to form the groove 100.
The side portion of the rotating cuttiny tool 180 coul.d be utilized to cut away metal to orm the groove 102. Thus~ the leading end portion of the end mill 178 would be moved into engagement with the valve sleeve 72 to form the end surface 15~ in the manner previously explained. Simultaneously therewith, the leading or axially outer end portion of the rotating cu~ting tool 180 would engage the central portion 132 of the valve sleeve to form the end surace 160 of the axially ¦exten ng inner groove l02.
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" .::` :' Once the two end mills have forlned the axiaLly outer end surEace 154 and the axially inner surfc~ce 160, the valve sleeve would be moved axially relative to the rotating end mills. Thus, the valve sleeve ~70uld be movecl axially toward the right (as viewed in Fig. 3) to enable the outer face 1~4 of the end mill 17~ to form the constant depth main section .
146 of the groove 100. This axial movement oE the valve sleeve would also cause the side port;on oE the rotating end mill 180 to cut away the main portion 16~ of the axially .
extending inner ~roove 102. The axial movement of the valve sleeve 72 would be stopped when the end mil]. 178 had been inserted far enough into the valve sleeve 72 to form the en~
face 142 and the end mill 180 and had been withdLawD from the valve sleeve 72 through a sufficient distance to Eorm the end surface 170. . ; -In view of the foregoing remarks it is apparent that the present invention provides a new and improved one-p1ece valve sleeve 72 and method by which the valve sleeve is formed. The hollow cylindrical`valve sleeve 72 has a plurality of .
relatively short axially extending internal grooves 100, 102, 104, and 106. The internal grooves 100 and 104 ex-tena in one axial direction from a central portion 132 of the valve sleeve while the grooves 102 and 106 extend in the opposite axial direction. ~herefore, at least some of the internal grooves are axially offset relative to other internal grooves. Since -each o the internal grooves 100, 102, 104, and 106 extends in only one axial direction from a central portion 132 oE the : -valve sleeve, the machining time required to form each of the grooves is xeduced.
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In accorcl~lnce ~1.ith another fe~ture o~ the present invention, it is possible to sirnultaneously ~orm two of the short axially extending grooves by using a pair o~ rotary cutting tools such as end mill.s 178 and 180. When the a%ially extending grooves 100, 102, 104, and 106 are to be formed in this manner, the end mills 178 and 180 are inserted into opposite axial. ends of the valve sleeve. Upon the occurrence of relative movement between the end mills 178 and 180 and the valve sleeve 72, the end mills simultaneously cut away metal to form a pair of axially ext,ending grooves in the one-piece valve sleeve. However, it is contemplated that the grooves .
100, 102, 104, and 106 could be sequentially formed one at a time th a singIe ~nd mill if desired.
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Claims (17)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A power steering apparatus comprising hydraulic motor means for assisting in operation of a vehicle steering gear, a housing having a plurality of passages connected in communication with a source of fluid and said hydraulic motor means, and valve means disposed in said housing for use in controlling fluid flow through said passages to thereby control operation of said hydrau-lic motor means, said valve means including an inner valve member and a valve sleeve circumscribing said inner valve member, said valve sleeve including outer side surface means for defining an array of outer grooves each of which opens outwardly and extends around said sleeve, said array of outer grooves including a first outer groove disposed in a central portion of said valve sleeve and connected in fluid communication with a first one of said passages in said housing, a second outer groove disposed to one axial side of the central portion of said valve sleeve and said first outer groove and connected in fluid communication with a second one of said passages in said housing, and a third outer groove disposed to another axial side of the central portion of said valve sleeve and said first groove and connected in fluid communication with a third one of said passages in said housing, said valve sleeve further including inner surface means for defin-ing a plurality of axially extending grooves on the inside of said valve sleeve, a first one of said plurality of axially extending grooves having a first end surface disposed in the central portion of said valve sleeve adjacent to said outer groove and a first main section which extends axially away from said first end surface in a first axial direction to a second end surface disposed to the one axial side of the central portion of said valve sleeve and adjacent to said second outer groove, a second one of said plurality of axially extending grooves having a third end surface disposed in the central portion of said valve sleeve adjacent to said first outer groove and a second main section which extends axially away from said third end surface in a second axial direc-tion which is opposite from said first axial direction to a fourth end surface disposed to the other axial side of the central portion of said sleeve and adajcent to said third outer groove.
2. An apparatus as set forth in claim 1 wherein said second end surface slopes away from the central portion of the valve sleeve in the first axial direction and has a central axis which intersects the central axis of the valve sleeve at a first acute angle, said fourth end surface slopes away from the central portion of the valve sleeve in the second axial direction and has a central axis which intersects the central axis of the valve sleeve at said first acute angle.
3. An apparatus as set forth in claim 1 wherein each of said axially extending grooves has an overall axial length which is approximately two-thirds of the axial length of said array of outer grooves.
4. An apparatus as set forth in claim 1 wherein said first end surface is disposed inwardly from a first axial side of said first outer groove and said second end surface is disposed in-wardly from a second axial side of said first outer groove.
5. An apparatus as set forth in claim 1 further including a first valve passage means extending between said second outer groove and said second end surface for conducting fluid between said first axially extending groove and said second outer groove, and second valve passage means extending between said third outer groove and said fourth end surface for conducting fluid between said second axially extending groove and said third outer groove.
6. A method of forming a valve, said method comprising the steps of providing a hollow valve sleeve, rotating first and second cutting tools about their central axes, engaging the inside of the hollow valve sleeve with the outer end portions of the rotating cutting tools at locations spaced apart from axial end portions of the valve sleeve, simultaneously forming first and second axially extending grooves having closed end portions inside the valve sleeve by moving the first and second rotating cutting tools and valve sleeve relative to each other while main-taining the rotating cutting tools in engagement with the inside of the valve sleeve, and subsequently moving the valve sleeve and cutting tools out of engagement with each other.
7. A method as set forth in claim 6 wherein said step of simultaneously forming first and second axially extending grooves includes the step of forming grooves having surface areas with semicircular cross-sectional configurations in a plane extending perpendicular to the central axes of the grooves by simultaneously cutting away material from the sleeve with the outer end portions of the first and second rotating cutting tools while moving the rotating cutting tools and valve sleeve relative to each other with the outer end portions of the cutting tools in engagement with the inside of the valve sleeve.
8. A method as set forth in claim 6 wherein said step of simultaneously forming first and second axially extending grooves having closed end portions includes the steps of forming one end portion of the first groove in a central portion of the valve sleeve, forming another end portion of the first groove adjacent to a first axial end portion of the valve sleeve, forming one end portion of the second groove in a central portion of the valve sleeve, and forming another end portion of the second groove adjacent to a second axial end portion of the valve sleeve.
9. A method as set forth in claim 6 wherein said first and second cutting tools have circular end faces and longitudinal-ly extending side sections, said step of simultaneously forming first and second axially extending grooves including the step of cutting away material from the valve sleeve with the circular end face of one of the cutting tools while simultaneously therewith cutting away material from the valve sleeve with the longitudinal-ly extending side section of the other cutting tool.
10. A method as set forth in claim 6 wherein said first and second cutting tools have circular end faces, said step of simultaneously forming first and second axially extending grooves includes the step of simultaneously cutting away material from the valve sleeve with the circular end faces of the first and second rotating cutting tools.
11. A method as set forth in claim 6 wherein said step of engaging the inside of the hollow valve sleeve with the outer end portions of the cutting tools includes the step of inserting the first cutting tool through one open axial end portion of the valve sleeve and inserting the second cutting tool through the other open axial end portion of the valve sleeve.
12. A method as set forth in claim 6 wherein said step of simultaneously forming the first and second axially extend-ing grooves includes the step of moving the valve sleeve axially relative to the first and second cutting tools.
13. A power steering apparatus comprising hydraulic motor means for assisting in operation of a vehicle steering gear, a housing having a plurality of passages connected in communication with a source of fluid and said hydraulic motor means, and valve means disposed in said housing for use in con-trolling fluid flow through said passages to thereby control operation of said hydraulic motor means, said valve means in-cluding an inner valve member and a valve sleeve circumscribing said inner valve member/ said valve sleeve including inner sur-face means for defining first and second axially extending grooves on the inside of said valve sleeve, each of said axially extending grooves having an axial length which is less than the axial extent of said valve sleeve and having opposite end por-tions which are spaced apart from axial end portions of said valve sleeve, said first axially extending groove having a main section which extends between first and second end surfaces of said first axially extending groove, said first and second end surfaces of said first axially extending groove being disposed axially inwardly of opposite axial ends of said valve sleeve, said second axially extending groove having a main section which extends between first and second end surfaces of said second axially extending groove, said first and second end sur-faces of said second axially extending groove being disposed axially inwardly of opposite axial ends of said valve sleeve, said first end surface of said first axially extending groove being disposed closer to a first axial end of said valve sleeve than said second end surface of said first axially extending groove and being spaced from the first axial end of said valve sleeve by a first distance, said first end surface of said second axially extending groove being disposed closer to the first axial end of said valve sleeve than said second end surface of said second axially extending groove and being spaced from the first axial end of said valve sleeve by a second distance which is greater than said first distance.
14. An apparatus as set forth in claim 13 wherein said second end surface of said first axially extending groove is spaced from a second axial end of said valve sleeve by a third distance, said second end surface of said second axially extend-ing groove being spaced from the second axial end of said valve sleeve by a fourth distance which is less than said third distance.
15. An apparatus as set forth in claim 14 wherein said valve sleeve further includes outer surface means for defining an array of outer grooves each of which opens outwardly and ex-tends around said sleeve, said first and second end surfaces of said first and second axially extending grooves being disposed inwardly of said array of outer grooves.
16. An apparatus as set forth in claim 15 further includ-ing first valve passage means extending between a first one of said outer grooves and said first end surface of said first axially extending groove for connecting said first one of said outer grooves and said first axially extending groove in fluid communication.
17. An apparatus as set forth in claim 16 further including second valve passage means extending between a second one of said outer grooves and said second end surface of said second axially extending groove for connecting said second one of said outer grooves and said second axially extending groove in fluid communication.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US89161078A | 1978-03-30 | 1978-03-30 | |
| US891,610 | 1992-06-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1116047A true CA1116047A (en) | 1982-01-12 |
Family
ID=25398520
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA324,148A Expired CA1116047A (en) | 1978-03-30 | 1979-03-26 | Power steering valve and method of making same |
Country Status (13)
| Country | Link |
|---|---|
| JP (1) | JPS54162340A (en) |
| AR (1) | AR215384A1 (en) |
| BE (1) | BE875193A (en) |
| BR (1) | BR7901933A (en) |
| CA (1) | CA1116047A (en) |
| DE (1) | DE2912791A1 (en) |
| DK (1) | DK130579A (en) |
| ES (2) | ES479030A1 (en) |
| FR (1) | FR2421097A1 (en) |
| GB (1) | GB2019796B (en) |
| IT (1) | IT1112483B (en) |
| LU (1) | LU81094A1 (en) |
| NL (1) | NL7902436A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9624900D0 (en) * | 1996-11-29 | 1997-01-15 | Adwest Steering Ltd | A power assisted steering mechanism |
| US6176343B1 (en) * | 1997-12-15 | 2001-01-23 | Trw Inc. | Vehicle steering apparatus |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3591139A (en) * | 1968-03-20 | 1971-07-06 | Arthur E Bishop | Method and apparatus for making valve sleeves |
| GB1241428A (en) * | 1968-11-15 | 1971-08-04 | Adwest Eng Ltd | Rack and pinion steering mechanisms for motor vehicles |
| US3709099A (en) * | 1970-08-11 | 1973-01-09 | Trw Inc | Convertible rack and pinion steering gear |
| GB1427705A (en) * | 1972-09-09 | 1976-03-10 | Burman & Sons Ltd | Manufacture of power-assisted steering gear |
-
1979
- 1979-03-22 GB GB7910067A patent/GB2019796B/en not_active Expired
- 1979-03-26 CA CA324,148A patent/CA1116047A/en not_active Expired
- 1979-03-28 ES ES479030A patent/ES479030A1/en not_active Expired
- 1979-03-29 BE BE0/194800A patent/BE875193A/en not_active IP Right Cessation
- 1979-03-29 NL NL7902436A patent/NL7902436A/en not_active Application Discontinuation
- 1979-03-29 JP JP3766879A patent/JPS54162340A/en active Pending
- 1979-03-29 FR FR7907923A patent/FR2421097A1/en active Granted
- 1979-03-29 LU LU81094A patent/LU81094A1/en unknown
- 1979-03-29 BR BR7901933A patent/BR7901933A/en unknown
- 1979-03-29 IT IT21414/79A patent/IT1112483B/en active
- 1979-03-30 DE DE19792912791 patent/DE2912791A1/en not_active Ceased
- 1979-03-30 DK DK130579A patent/DK130579A/en not_active Application Discontinuation
- 1979-03-30 AR AR276009A patent/AR215384A1/en active
-
1980
- 1980-02-12 ES ES488498A patent/ES488498A1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DK130579A (en) | 1979-10-01 |
| ES479030A1 (en) | 1980-08-16 |
| NL7902436A (en) | 1979-10-02 |
| BR7901933A (en) | 1979-10-23 |
| ES488498A1 (en) | 1980-09-16 |
| IT7921414A0 (en) | 1979-03-29 |
| FR2421097A1 (en) | 1979-10-26 |
| JPS54162340A (en) | 1979-12-22 |
| BE875193A (en) | 1979-07-16 |
| GB2019796B (en) | 1983-04-27 |
| FR2421097B1 (en) | 1983-01-14 |
| LU81094A1 (en) | 1979-06-19 |
| DE2912791A1 (en) | 1979-10-04 |
| IT1112483B (en) | 1986-01-13 |
| AR215384A1 (en) | 1979-09-28 |
| GB2019796A (en) | 1979-11-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |