DK141929B

DK141929B - HYDROSTATIC AID POWER STEERING NECESSARY FOR MOTOR VEHICLES

Info

Publication number: DK141929B
Application number: DK317477A
Authority: DK
Inventors: A Lang
Original assignee: Zahnradfabrik Friedrichshafen
Priority date: 1976-07-22
Filing date: 1977-07-13
Publication date: 1980-07-21
Also published as: YU176377A; DE2633011B2; DE2633011C3; FR2359018A1; JPS5312779A; SE421604B; DK141929C; DK317477A; IT1079982B; FR2359018B1; SE7708378L; JPS6140586B2; DE2633011A1; BR7704805A; PL199795A1

Description

(11) FREMLÆGGELSESSKRIFT 141929 DANMARK (51) Intel.3 B 62 D 5/06 «(21) Ansøgning nr. 317^-/77 (22) Indleveret den 13· Jul. 1977 (23) Løbedag 13· jul. 1977 (44) Ansøgningen fremlagt og ^(11) PRESENTATION 141929 DENMARK (51) Intel.3 B 62 D 5/06 '(21) Application No. 317 ^ - / 77 (22) Filed on 13 · Jul. 1977 (23) Race day 13 · Jul. 1977 (44) The application presented and ^

fremlæggelsesskriftet offentliggjort den dl. JUX. 19oUthe petition published on dl. Jux. 19oU

DIRΕΚΤΟRATET FORTHE DIRECTORY FOR

PATENT- OG VAREMÆRKEVÆSENET OO) Prioritet begæret fra denPATENT AND TRADEMARKET OO) Priority requested from it

22. jul. 1976, 2633011, DEJul 22 1976, 2633011, DE

(71) ZAHNRADFABRIK FRIEDRICHS HAF EN AKTIENGESELLSCHAFT, Postfach 507, Pried= richshafen, DE.(71) ZAHNRADFABRIK FRIEDRICHS HAF AN AKTIENGESELLSCHAFT, PO Box 507, Pried = richshafen, DE.

(72) Opfinder! Amin Lang, Rheinstr. 10, Schwaebisch Gmuend, DE.(72) Inventor! Amin Lang, Rheinstr. 10, Schwaebisch Gmuend, DE.

(74) Fuldmægtig under sagens behandling:(74) Plenipotentiary in the proceedings:

Civilingeniør M.Gregersen._ (54) Hydrostatisk hjælpekrafts tyring, navnlig til motorkøretøjer.Civil engineer M.Gregersen._ (54) Hydrostatic auxiliary power steering, especially for motor vehicles.

Opfindelsen angår en hydrostatisk hjælpekraftstyring, navnlig til motorkøretøjer, af den i krav l's indledning angivne art.The invention relates to a hydrostatic auxiliary power control, in particular for motor vehicles, of the kind specified in the preamble of claim 1.

Hjælpekraftstyringer af denne art kan i det væsentlige inddeles i to udførelsesformer: Den ene udførelsesform er udstyret med en styreventil, der i neutralstilling blokerer arbejds-cylinderen, medens den anden udførelsesform har en styreventil, der i neutralstilling frembringer en forbindelse fra en håndpumpe til arbejdscylinderen, som det f.eks. er beskrevet i et trykskrift ”ZF-Ross-Servostat, hydrostatische Lenkung, Typen-reihe 8440 bis 8455" fra Zahnradfabrik Friedrichshafen AG.Auxiliary power controls of this kind can be essentially divided into two embodiments: one embodiment is provided with a control valve which in neutral position blocks the working cylinder, while the other embodiment has a control valve which in neutral position provides a connection from a hand pump to the working cylinder, such as the is described in a publication "ZF-Ross-Servostat, Hydrostatic Lenkung, Typen-range 8440 bis 8455" from Zahnradfabrik Friedrichshafen AG.

Hjælpekraftstyringer med blokerede arbejdscylindre anvendes fortrinsvis i arbejdsmaskiner, f.eks. i byggeindustrien, 141929 2 eller i maskiner i terræn. I køretøjer til disse formål er et automatisk tilbageløb af de drejede hjul til en stilling for kørsel ligeud ikke ønskelig. Betjeningen af arbejdshydraulikken stiller nemlig fra tid til anden så store krav til føreren, at 5 han må bruge begge hænder hertil og slippe rattet. Derfor må det være sikret, at den indstillede kørselsretning ikke ændres. Styreventilen, der i neutralstilling blokerer arbejdscylinderen, hindrer en omstilling af hjulene på grund af stød fra kørebanen.Auxiliary power controls with blocked work cylinders are preferably used in work machines, e.g. in the construction industry, 141929 2 or in machinery in terrain. In vehicles for these purposes, an automatic return of the turned wheels to a straight-forward position is not desirable. The operation of the working hydraulic does, from time to time, place such great demands on the driver that he has to use both hands for this purpose and release the steering wheel. Therefore, it must be ensured that the set direction of travel does not change. The control valve, which in neutral position blocks the working cylinder, prevents the wheels from being changed due to impacts from the roadway.

10 Hjælpekraftstyringer med en styreventil, der frembringer en forbindelse fra håndpumpen til arbejdscylinderen, en styreventil efter gennemstrømningssystem, anvendes fortrinsvis f.eks. i køretøjer, der bevæger sig på faste kørebaner. I dette tilfælde ønsker føreren en så god kørebanekontakt som muligt og et au-15 tomatisk tilbageløb af hjulene fra en stilling til kørsel i kurver til en stilling til kørsel ligeud. Et sådant køretøj kan også iden vanskeligheder trækkes, da det automatisk løber efter trækkøretøjet.Auxiliary power controls with a control valve which produce a connection from the hand pump to the working cylinder, a control valve according to flow system, are preferably used e.g. in vehicles moving on fixed lanes. In this case, the driver wants as good a lane contact as possible and an au-15 tomato return of the wheels from a position for driving in curves to a position for driving straight ahead. Such a vehicle can also be difficult to pull, as it automatically runs after the towing vehicle.

Ved hydrostatiske hjælpekraftstyringer optræder der sær-20 lige problemer, fordi en fuldstændig fyldning af arbejdscylinderen må være sikret i enhver driftstilstand. Ved en styreventil efter gennemstrømningssystemet kan trykolie eftersuges gennem kortslutningsventiler, der er indskudt mellem håndpumpen og o-liebeholderen. Ved en hjælpekraftstyring med blokeret styreven-25 til er kortslutningsventilerne dog uvirksomme i styreventilens neutralstilling og kan derfor ikke forhindre, at der opstår et vakuum i arbejdscylinderen. Et vakuum, der opstår i arbejdscylinderen i styreventilens neutralstilling, kan så kun udfyldes ved en drejningsbevægelse på rattet. Vakuummet kan opstå på 30 grund af lækolie ved blokeringskanterne og hurtigt blive større ved en såkaldt opgyngningsproces, d.v.s., der opstår voksende svingninger i vakuummet. Dette forløb kan forklares nærmere som følger: Virker der på arbejdscylinderens stempel, f.eks. på grund af et kørebanestød, en kraft mod højre, vil der i den 35 højre cylinderledning blive opbygget et tryk, og der opstår en lækstrømning til oliebeholderen ved den lukkede styrekant mellem ventilstemplet og styrehuset. I det overfor liggende trykrum i arbejdscylinderen kan der som følge af blokeringen ikke strømme nogen trykolie efter, så at der dannes et vakuum. Vir- 3 141929 ker der derefter en kraft i modsat retning på stemplet, vil denne kraft på grund af vakuummet i det venstre trykrum ikke møde nogen midstand. Stemplet bevæger sig tværtimod uhindret mod venstre et vejstykke, der svarer til lækstrømningen. Ved 5 denne bevægelse opstår der så et vakuum i det højre trykrum.In hydrostatic auxiliary power controls, special problems occur because a complete filling of the working cylinder must be ensured in every operating condition. In a control valve according to the flow system, pressure oil can be aspirated through short-circuit valves inserted between the hand pump and the oil tank. However, in an auxiliary power control with blocked control valve 25, the short-circuit valves are inoperative in the neutral position of the control valve and therefore cannot prevent a vacuum in the working cylinder. A vacuum created in the working cylinder in the neutral position of the control valve can then only be filled by a rotational movement of the steering wheel. The vacuum can occur due to leakage oil at the blocking edges and quickly become larger by a so-called buildup process, i.e., increasing fluctuations in the vacuum occur. This process can be explained in more detail as follows: Does the working cylinder piston, e.g. due to a roadway impact, a force to the right, a pressure will build up in the 35 right cylinder line and a leakage flow to the oil reservoir will occur at the closed guide edge between the valve piston and the steering body. In the opposite pressure chamber in the working cylinder, as a result of the blockage, no pressure oil can flow afterwards to create a vacuum. If a force is then applied in the opposite direction to the piston, this force, due to the vacuum in the left pressure chamber, will meet no middle distance. On the contrary, the piston moves unobstructed to the left a section of road corresponding to the leakage flow. At this motion, a vacuum then arises in the right pressure chamber.

Slår stemplet an mod oliesøjlen i det venstre trykrum, opstår der dér på grund af massekræfter et forholdsvis højt tryk, og den tilsvarende lækoliemængde strømmer ud. Herved vil arbejds-stemplet i arbejdscylinderen komme til at udføre svingninger 10 med tiltagende amplitude, hvad der kan virke meget uheldigt på kørselssikkerheden.If the piston touches the oil column in the left pressure chamber, there is a relatively high pressure there due to mass forces and the corresponding amount of leakage oil flows out. Hereby, the working piston in the working cylinder will perform oscillations 10 with increasing amplitude, which can have a very adverse effect on the driving safety.

Den beskrevne mangel vil kunne afhjælpes ved, at man forbinder de to arbejdscylindre-ledninger med oliebeholderen over kortslutningsventiler, der åbner i retning mod trykrumme-15 ne. Denne indretning giver dog, bortset fra betydelige meromkostninger, en yderligere sikkerhedsrisiko, da styringen vil svigte, hvis en af disse ventiler bliver uvirksom.The deficiency described can be remedied by connecting the two working cylinder lines to the oil tank over short-circuit valves which open in the direction of the pressure chambers. However, apart from significant additional costs, this device presents an additional safety risk as the control will fail if one of these valves becomes inoperative.

Den foreliggende opfindelse tager sigte på at angive en hydrostatisk hjælpekraftstyring af den omhandlede art, ved 20 hvilken de ovennævnte ulemper er undgået og dannelse af et forstyrrende vakuum i arbejdscylinderen er forhindret, uden at der kræves en større indsats af byggedele for ikke at påvirke kørselssikkerheden.The present invention aims to provide a hydrostatic auxiliary force control of the kind in which the above-mentioned drawbacks are avoided and the formation of a disruptive vacuum in the working cylinder is prevented, without requiring greater effort on the part of the building so as not to affect driving safety.

Dette opnås ifølge opfindelsen ved, at hjælpekraftsty-25 ringen er udformet som angivet i krav l's kendetegnende del.This is achieved according to the invention in that the auxiliary power control is designed as defined in the characterizing part of claim 1.

Ved denne udformning af hjælpekraftstyringen opnår man, at styreforholdet af den hydrostatiske hjælpekraftstyring med blokeret arbejdscylinder bliver betydelig forbedret, og desuden bliver de af kavitation betingede svingninger af arbejds-30 stemplet i arbejdscylinderen på tilforladelig måde forhindret.In this embodiment of the auxiliary power control, the control ratio of the hydrostatic auxiliary power control with the blocked working cylinder is significantly improved, and in addition the cavitation-dependent oscillations of the working piston in the working cylinder are reliably prevented.

Denne virkning understøttes ved udformning af hjælpekraftstyringen som angivet i krav 2. En sådan understøtning af virkningen opnås også ved udformning af hjælpekraftstyringen som angivet i krav 3. Egenvægten af ventilbøsningen vil virke 35 til at sikre, at den spalte, der dannes ved hver styrekant u-den overdækning i den neutrale stilling ikke kan indsnævres.This effect is supported by designing the auxiliary power control as set forth in claim 2. Such support of the effect is also obtained by designing the auxiliary power control as set forth in claim 3. The self-weight of the valve bushing will act to ensure that the gap formed at each guide edge -the cover in the neutral position cannot be narrowed.

Hjælpekraftstyringen ifølge opfindelsen forklares nærmere under henvisning til tegningen, på hvilken 4 141929 fig. 1 viser et forenklet længdesnit gennem en udførelsesform for hjælpekraftstyringen i neutralstilling, og fig. 2 et olieskema for hjælpekraftstyringen i fig. 1.The auxiliary force control according to the invention is explained in more detail with reference to the drawing, in which FIG. 1 shows a simplified longitudinal section through an embodiment of the auxiliary power control in neutral position; and FIG. 2 shows an oil diagram for the auxiliary power control of FIG. First

5 Ved drejning af et rat 1 drives en rotor 2 i en hånd pumpe 3 over en styrespindel 4, en torsionsstav 5 og en ledaksel 6. Derved bliver torsionsstaven 5 selv drejet, så at der ker en relativdrejning mellem styrespindlen 4 og ledakslen 6.5 When rotating a steering wheel 1, a rotor 2 is driven in one hand by pump 3 over a guide spindle 4, a torsion rod 5 and a joint shaft 6. The torsion rod 5 itself is then rotated so that there is a relative rotation between the control spindle 4 and the joint shaft 6.

En med en radialboring 9 forsynet ventilbøsning 7 i en styre-10 ventil 8 er dels over en medbringerfortanding 40 forbundet med ledakslen 6 og dels over en skrueformet slidse 10, i hvilken der indgriber en medbringerstift 11, der er indpresset i styrespindlen, forbundet med styrespindlen 4. Ved denne anordning er en aksial forskydning af ventilbøsningen 7 inden for et be-15 stemt styrespillerum mulig på kendt måde. Styrespillerummet for ventilbøsningen 7 er begrænset såvel ved hjælp af slidsen 10 og medbringerstiften 11 som også ved hjælp af en som dødgangskobling virkende anslagsring 12. Efter overvindelse af styrespillerummet bliver det drejningsmoment, der virker på 20 rattet, derfor ikke blot over stiften 11 og slidsen 10 overført til ventilbøsningen 7, men yderligere overført over an-slagsringen 12, der er forbundet med ventilbøsningen og med flankespillerum (ikke synlig] indgriber i styrespindlen 4. Forbindelsen mellem ventilbøsningen 7 og anslagsringen 12 sker o-25 ver en let forskydelig kilefortanding 40 og 41. Arbejdsstrøm-men fra en oliepumpe 13 ledes gennem tilløbskanaler 14 og 14A i et styrehus 15 og gennem styreventilen 8 alt efter drejningsretningen af rattet 1 til en trykkanal 16 eller 17 og dermed til håndpumpen 3. Arbejdstrykket fra oliepumpen 13 er indstil-30 let på en højeste værdi ved hjælp af en trykbegrænsningsven-til 18.A valve sleeve 7 provided with a radial bore 9 in a guide valve 8 is connected, partly over a driver tooth 40, to the shaft 6 and partly over a helical slot 10, in which engages a driver pin 11 which is pressed into the control spindle, connected to the control spindle. 4. In this arrangement, an axial displacement of the valve bushing 7 within a determined control clearance is possible in known manner. The control space for the valve bushing 7 is limited both by the slot 10 and the carrier pin 11 as well as by a stop ring acting as deadlock clutch 12. After overcoming the control room, the torque acting on the steering wheel becomes not only above the pin 11 and the slot 10 transferred to the valve bushing 7, but further transferred over the abutment ring 12, which is connected to the valve bushing and with flank clearance (not visible) engages in the control spindle 4. The connection between the valve bushing 7 and the stop ring 12 occurs over a slightly sliding wedge tooth 40 and 41 The workflow from an oil pump 13 is passed through inlet ducts 14 and 14A in a control housing 15 and through the control valve 8 according to the direction of rotation of the steering wheel 1 to a pressure channel 16 or 17 and thus to the hand pump 3. The working pressure from the oil pump 13 is adjusted to 30. a maximum value by means of a pressure limiting valve 18.

Den af håndpumpen doserede arbejdsstrøm når svarende til rattets styreslag fra trykkanalen 16 eller 17 over en forbindelseskanal henholdsvis 20 og 21 til et trykrum henholdsvis 35 22 og 23 i en arbejdscylinder 24. Den olie, der fortrænges fra det i øjeblikket aflastede trykrum i arbejdscylinderen 20, strømmer trykløst gennem en forbindelseskanal 20 eller 21, styreventilen 8 og en mellemkanal 25 eller 26 til en tilbageløbskanal 27, der fører til en beholder 28. I tilbageløbskanalen 5 H1929 27 og i en yderligere kanal 33, der er forbundet med tilbageløbskanalen 27, er der indskudt kortslutningsventiler henholdsvis 31 og 32, der lukker sig i retning mod beholderen 28. Disse kortslutningsventiler har den opgave at muliggøre en ef-5 terindskydning af trykolie, når den af drivmaskinen drevne o-liepumpe 13 svigter, altså ved styring uden hydraulisk understøttelse, ved hjælp af håndpumpen 3 fra beholderen 28. Kortslutningsventilen 31 har ved styring med hjælpekraft den yderligere opgave at efterindsuge ekstra trykolie ved en opadbevæ-10 gelse af arbejdscylinderstemplet, fordi den fra trykrummet 23 fortrængte oliemængde ikke er tilstrækkelig til at fylde trykrummet 22. Denne sidste efterindsugning har sin årsag i de forskellige slagvolumen af de to trykrum 22 og 23.The working flow metered by the hand pump reaches the steering stroke of the steering wheel from the pressure channel 16 or 17 over a connecting channel 20 and 21 respectively to a pressure chamber 35 and 22 respectively in a working cylinder 24. The oil displaced from the currently unloaded pressure space in the working cylinder 20, flows pressurelessly through a connecting duct 20 or 21, the control valve 8 and an intermediate duct 25 or 26 to a reflux duct 27 leading to a container 28. In the reflux duct 5 H1929 27 and in a further duct 33 connected to the reflux duct 27, injected short-circuit valves 31 and 32, respectively, which close in the direction of the container 28. These short-circuit valves have the task of enabling an additional injection of pressure oil when the oil pump 13 driven by the drive machine fails, ie by control without hydraulic support, at by means of the hand pump 3 from the container 28. The short-circuit valve 31 has the additional task of controlling with power the additional pressure oil is sucked in by an upward movement of the working cylinder piston, because the amount of oil displaced from the pressure chamber 23 is not sufficient to fill the pressure chamber 22. This last after suction has its cause in the different impact volumes of the two pressure spaces 22 and 23.

Ifølge opfindelsen er ventilbøsningen 7 udformet såle-15 des, at det nederste trykrum 22, der er tilsluttet til en ringnot 34 i huset, i den viste neutralstilling, fig. 1, er blokeret ved hjælp af en styrekant 35. Det øverste trykrum 23, der er tilsluttet til en anden husringnot 36, står derimod over en åben styrekant 37 over boringen 9 og over et inderrum 38 i ven-20 tilbøsningen 7 i forbindelse med trykkanalen 17, der fører til håndpumpen 3. Med hensyn til blokeringsvirkningen fås der herved samme overraskende effekt som ved en på begge sider spærret arbejdscylinder, da et i trykrummet 22 virkende trykstød umiddelbart opfanges ved styreventilen 8, medens et i trymrukket 23 25 virkende trykstød ligeledes bliver blokeret ved styreventilen ad omvejen over håndpumpen 3.According to the invention, the valve bushing 7 is designed so that the lower pressure chamber 22, which is connected to a ring groove 34 in the housing, in the neutral position shown, FIG. 1, is blocked by a guide edge 35. The top pressure chamber 23, which is connected to a second housing groove 36, on the other hand, faces an open guide edge 37 over the bore 9 and over an inner space 38 in the friend sleeve 7 in connection with the pressure channel. 17, which leads to the hand pump 3. With regard to the blocking effect, the same surprising effect is obtained as for a working cylinder which is blocked on both sides, since a pressure shock acting in the pressure chamber 22 is immediately caught by the control valve 8, while a pressure shock acting in the drum jerk 23 25 also becomes blocked by the control valve by the detour over the hand pump 3.

Hjælpekraftstyringen virker ved drejning af rattet mod venstre eller mod højre på den allerede foran antydede, kendte måde.The auxiliary power control acts by turning the steering wheel to the left or to the right in the already known, known way.

30 I fig. 1 og 2 er neutralstillingen vist, i hvilken ven tilbøsningen 7 indtager sin midterstilling. Denne midterstilling fås altid, når der ikke virker kræfter på rattet 1 og de styrede hjul. Den af oliepumpen 13 frembragte oliestrøm ledes fra tilløbskanalen 14 over de åbne styrekanter i ventilbøsnin-35 gen 7 til mellemkanalerne 25 og 26 og fra disse gennem tilbageløbskanalen 27 til beholderen 28. Olien i de andre kanaler og i håndpumpen 3 er herved ikke i bevægelse. Som allerede nævntIn FIG. 1 and 2, the neutral position is shown in which the member 7 takes up its center position. This center position is always obtained when the steering wheel 1 and the steering wheels do not work. The oil flow produced by the oil pump 13 is conducted from the inlet duct 14 over the open guide edges of the valve bushing 7 to the intermediate ducts 25 and 26 and from these through the reflux duct 27 to the container 28. The oil in the other ducts and in the hand pump 3 is thereby not moving. As already mentioned

Claims

6 141929 above, the working cylinder is blocked partly immediately by the control valve 8 and partly by the hand pump 3 at the control valve, so that the guided wheels maintain the set direction of travel. If in the neutral position of the valve bushing 7 for the oil pad enclosed in the pressure chamber 22 over the piston rod 30 a force, for example due to a roadway shock, a leakage flow can be formed from the housing ring groove 34 to the intermediate channel 25 and thus to the return channel 27. In order that no vacuum can arise in the pressure chamber 23, then the short-circuit valve 32, which allows oil to flow through the housing ring 36 to the pressure chamber 23. reacts in the opposite direction to the oil pad enclosed in the pressure chamber 23, this does not cause disturbing growing oscillations in the vacuum because the short-circuit valve 32 reacts at the subsequent reversal of the force of the thrust. The driving safety is thereby significantly increased. It is advantageous that the guide edges of the valve sleeve 7 which, by virtue of the built-in position of the auxiliary force control and the gravity of the valve sleeve by themselves, act in the direction of overlay, are carried out with overlay. In the present embodiment, this applies to the guide edge 35.

1. Hydrostatic auxiliary power control, in particular for motor vehicles, with a steering wheel-driven hand pump, a high-pressure oil pump operated by the vehicle's engine, and a control valve adjustable depending on the rotation of the steering wheel in both directions , which is interposed between channels leading from the hand pump to a working cylinder, the pressure oil transported by the high pressure oil pump in the control valve neutral position being able to flow back to a container, as well as with a short-circuit valve between each of the channels leading to the hand pump and a reflux line for suction of pressure oil, characterized in that the control valve (81 in neutral position forms a connection from one side of the hand pump (31 to a pressure chamber) (231 in the working cylinder (241), while the other pressure chamber (221 is blocked by means of the control valve (81.