JP2684552B2 - Fluid distribution device for vehicle power steering system - Google Patents

Description

The present invention includes a pair of parallel circuits between a pressure source and a tank, each circuit including at least one first variable throttle and at least one second variable throttle in series. By means of the input member, the variable throttles in the two circuits are arranged to control a fluid motor having opposed chambers connected to the corresponding circuits at an intermediate point between the pair of first and second variable throttles. A fluid distribution device of a type, in particular a vehicle power steering system, of a type adapted to be operated in synchronism, each circuit further comprising a fixed throttle which is activated by an input member in synchronism with a variable throttle. It is about. A fluid distribution device of this type is described in GB 2,028,240. The fluid distribution device described in this specification includes a cylindrical sleeve and a rotor, and a fixed throttle in the shape of a through passage of a reduced cross section provided in the rotor,
During operation of the rotor, downstream of the second variable throttle which is operated in the opening direction so as to discharge the non-pilot-controlled chamber of the fluid motor, between the second variable throttle and the return to the tank which are activated and which are operated. Is closed and the flow of fluid returning to the tank is forced to flow to a branch passage passing through this fixed throttle. This construction, in a manner known per se, makes it possible to regulate the noise of the fluid by creating a head loss in the return circuit to the tank when the distributor is activated, but the operation of the fixed throttle The insertion of the throttle into the circuit is not controlled and there is a risk that cavitation or even impact can occur in the distributor. The object of the present invention is to reduce the noise of the fluid during operation significantly, and to make the structure inexpensive and simple, sturdy and reliable in operation, without affecting the accuracy and balance of the distributor. It is an object of the present invention to improve the above-mentioned fluid distribution device so that it can be variously adapted depending on the type of the distribution device. To this end, the invention comprises a pair of parallel circuits between the pressure source and the tank, each circuit comprising at least one first variable throttle and at least one second variable throttle in series. By means of the input member, the variable throttles in the two circuits are arranged to control a fluid motor having opposed chambers connected to the corresponding circuits at an intermediate point between the pair of first and second variable throttles. The first fixed throttle and the second fixed throttle, which are operated in synchronism with each other, are arranged downstream of the first variable throttle and alternately activated by an input member in synchronization with the variable throttle. A fluid distribution device further comprising a fixed throttle, each fixed throttle being formed by a radial concave surface provided on at least one surface of the two distribution members. To provide the device fluid distribution device There. According to a preferred feature of the invention, the first fixed aperture and the second fixed aperture
The fixed throttle is adapted to be operated downstream of the second variable throttle in each circuit. According to another preferred feature of the present invention, the first fixed diaphragm and the second fixed diaphragm are respectively activated in the downstream side of the first variable diaphragm and the second variable diaphragm of each circuit. The fixed throttle to be placed is located on the downstream side of the variable throttle which is operated in the closing direction by the input member. According to this configuration, the fixed throttle, which is normally inactive, is activated immediately after the distributor is activated, downstream of the variable throttle of each circuit that is activated in the closing direction.
A back pressure is generated immediately downstream of the closed variable throttle, and the head loss caused thereby can return the flow of the fluid disturbed and disturbed considerably by the closing of the variable throttle to an effective laminar flow, and thus in the distributor. The fluid noise can be greatly reduced. The above and other features and advantages of the present invention will become apparent from the following description of embodiments, which refers to the accompanying drawings. In the following description and drawings, the same or similar components are designated by the same reference numerals. In the detailed description and the claims, the term "fixed throttle" means a throttle having a constant reduced passage area over most of the working stroke of the distributor. By "actuated" by a fixed throttle is meant inserting or adding the throttle from a desired point in time into a fluid flow path that has not been required to pass through this fixed throttle. First, in FIG. 8, a pair of opposing working chambers V ₁ and V ₂
A conventional arrangement in a fluid distribution device for controlling a fluid motor V with is shown. The fluid distributor forms two parallel fluid circuits α, α ′ between the pressure source S and the low pressure tank or reservoir R, each fluid circuit comprising a first and a second fluid circuit.
Variable throttles A, B or A ', B' are provided, which are adapted to be actuated synchronously by an input member 1 of the distributor, which input member is, for example, for a motor vehicle power steering system. The hydraulic motor V is in this case connected to the steering mechanism or wheels of the vehicle. In the structure of such a steering device, when the input member 1 is operated in one direction, the first
Variable aperture A is opened when the closed second variable throttle B simultaneously, and the first variable throttle A 'is closed at the same time the second variable throttle B' pressure of the chamber V ₁ of the fluid motor V open parallel fluid circuit , The fluid contained in the other chamber V ₂ of the fluid motor is discharged to the tank R through the opened second variable throttle B ′. The operation of the dispensing device in the opposite direction is the reverse of the above. 1 to 3 show a first embodiment of the structure of a fluid distribution device according to the present invention. In FIG. 1, it is shown that variable diaphragms A, B and A ', B'are formed on the first distribution member 2 and the second distribution member 3, respectively, and these distribution members 2 and 3 are in contact with each other. It has adjacent cooperating surfaces represented by the plane 4. As in the conventional case, the variable diaphragm has a flat surface 4
Along with the distribution members 2 and 3 are actuated by relative displacement with respect to each other from the central rest position shown in FIG.
In detail, the first variable throttle A cooperates with the inlet O of the first distributor 2 connected to the pressure source S and the distributor E of the second distributor 3 connected to the chamber V ₁ of the fluid motor V. It is formed between the edges. The second variable throttle B is formed between the cooperating edges of the distribution port E and the intermediate port H of the first distribution member 2 separated from the inlet O. As in the conventional case, the first and second variable apertures A
The edges of the first distribution member 2 forming B and B are chamfers l ₁ and l ₂
Is provided. According to the invention, an intermediate port F is formed between the outlet G and the outlet E of the second distributor 3 connected to the tank R. The first distributing member 2 is formed with a central opening I extending to both ends of the discharge port G along the plane 4 and communicating with an adjacent intermediate opening F. The central opening I is fixed to the first distributing member 2. An intermediate opening H is separated by a web portion 5, said web portion 5 extending along a plane 4 underneath the intermediate opening F, the face d of said web portion facing the second distribution member 3 being a distance from the plane 4. It is arranged slightly offset by h (in the part of the first distribution member 2 between the chamfers l ₁ and l ₂ the surface facing the second distribution member 3 is a variable diaphragm A, B or A ′, B). 'Match plane 4 so that one or the other can be completely closed). Therefore, when a relative displacement occurs between the distribution members 2 and 3, the web portion 5 of the first distribution member 2 will be
To form a fixed diaphragm C or D between the intermediate opening F and the intermediate opening H or the central opening I in cooperation with one or the other of the edges of
The cross-sectional area of this fixed aperture is determined by the separation distance h. The structure of the distributor described above is symmetrical in all respects with respect to the other parallel fluid circuit α '. For example, the first distribution member 2 is
When displaced to the left in the figure, the variable diaphragms A and B'will be closed, while the variable diaphragms A'and B will be opened. When this relative displacement of the distribution member occurs, then fixed throttles C and D are added in the circuit downstream of the variable throttle which closes in the corresponding circuit. Therefore, not only the fluid returning from the distribution port E leading to the chamber V ₁ to the tank R, but also the residual flow of the pressurized fluid escaping from the distribution port E leading to the chamber V ₂ to the tank R when the second variable throttle B ′ is closed, Laminar flow can be created at ports I and G, which will pass through the corresponding fixed throttles in the operating state, allowing a noise reduction of the fluid which can reach 30 dB. When the distributor is activated, the fluid pressure difference between the distributor port E and the return ports I and G corresponding to the discharge side chamber of the fluid motor V (ie, chamber V _{1 in the} above example) is Mouth I and G
Is smaller than the pressure difference between the other distribution port and therefore the fixed throttles C and C'may be smaller than the fixed throttles D and D ', in which case the first distribution between the ports H and F. The surface d of the solid web portion 5 of the member 2 may be provided with a step as indicated by d'in FIG. 2 and 3 show a specific embodiment of the structure of the dispensing device shown schematically in FIG. A distributor of this type with a star-shaped rotor is described in EP-A-0,095,415 in the name of the Applicant, the content of which is referenced in the following description.
The first distribution member 2 is in the form of a flat star rotor with radial arms and is housed in a circular chamber 6 of a stator 7 consisting of an assembly of two annular end members 8 and 9 and an annular spacer member 10. The spacer members 10 define the outer circumference of the chamber 6 and the different members of the stator 7 are connected by bolts 11 extending axially between adjacent arms of the first distributor member or rotor 2. The rotor 2 is centrally connected to the input member or shaft 1. As shown, the mouths E, F, G are formed on at least one of the flat axial surfaces of the rotor arms, the mouths H, I are formed on the arms of the rotor 2, and the inlet O is the rotor 2 described above. Is formed between the adjacent arms. 4 and 5 show a second embodiment of the structure of the dispensing device according to the invention. In this embodiment, the first distribution member 2 has two intermediate ports H ₁ and H ₂ defined by its two separate web parts 5 ₁ and 5 ₂ between the inlet O and the central port I, The second distribution member 3 is an intermediate first distribution port E ₁ and second distribution port.
E ₂ and the second outlet is the corresponding chamber V ₁ of the fluid motor or
It is connected to V ₂ . As is clearly shown in FIG. 4, the first variable diaphragm A is formed by the adjoining edges of the inlet O and the first distribution opening E ₁ , while the second variable diaphragm B is formed by the first distribution member 2. Is formed between the intermediate opening H ₂ and the adjacent edge of the second distribution port E ₂ of the second distribution member 3. The first fixed aperture C is the second
The second fixed aperture D is formed by the step portion d _{1 on} the surface of the web portion 5 ₁ arranged on the side opposite to the variable aperture B and facing the second distribution port E _2. There is formed between the central port I and the intermediate port F by setback d ₂ extending across the second web portion 5 ₂ of the entire surface of the first distribution member 2. This embodiment operates in the following manner. If the first distributing member 2 is displaced leftward in FIG. 4 with respect to the second distributing member 3, the variable diaphragms A and B'will be closed and the variable diaphragms A'and B will be opened. At the same time, variable diaphragm A with fixed diaphragm C closed
Is added in the fluid flow path between the distribution ports E ₁ and E ₂ on the downstream side. In the other circuit, the variable diaphragm B'where the fixed diaphragm D'is closed.
Between the ports F and G is activated immediately downstream of. In this embodiment, a fixed throttle is not added in the return flow path between the return chamber V ₁ and the tank R, and therefore downstream of the variable throttle, which closes to restrict the flow of high pressure fluid. The turbulent flow generated through the variable throttles is reduced by the back pressure generated by the fixed throttles at the mouth between the closed variable throttles and the corresponding fixed throttles. Substantially laminar flow can occur on return to the downstream tank. FIG. 5 is a partial view similar to FIG. 2 showing the arrangement of the ports of FIG. 4 for a distributor having a star rotor. The third embodiment shown in FIGS. 6A, 6B and 7 is in principle similar in all respects to that described with reference to FIGS. 4 and 5, but in this case the inlet O and the exhaust The difference is that the circuit portion between the outlet G and the second distributing member, that is, each arm of the star-shaped rotor 2 is not formed in series in the circumferential direction, and the first portion of this circuit is the outer circumference of each arm. The second part of this circuit, while being formed in a section, is offset radially inward, closer to the base of the arm, as clearly shown in FIG. The communication is established by the Z-shaped second distribution port E ₂ of the second distribution member 3. Referring again to FIG. 8, in the embodiment shown in FIGS. 1 and 2, the fixed throttles C and D are arranged in the parallel fluid circuit α at the positions indicated by points γ ₂ and δ, respectively, and D 'is the point gamma' is disposed within the 'fluid circuit α in' ₂ and [delta]. In the embodiment shown in FIGS. 4 to 7, the fluid circuit α is
The fixed throttles C and D therein are arranged at points γ ₁ and δ, respectively, and the fixed throttles C ′ and D ′ are likewise arranged in the fluid circuit α ′ at points γ ′ ₁ and δ ′.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a developed sectional view of a first embodiment of the structure of a fluid distributor according to the present invention, and FIG. 2 is a schematic view of a star-shaped rotor fluid distributor having the structure of FIG. FIG. 3 is a sectional view, FIG. 3 is a side view showing a half portion of the distributor shown in FIG. 2 in section, FIG. 4 is a developed sectional view similar to FIG. 1 showing a second embodiment of the present invention, and FIG. FIG. 6 is a partial schematic sectional view of a star-shaped rotor type fluid distribution device having the structure of FIG. 4, FIGS. 6A and 6B show a third embodiment of the present invention along lines 6A and 6B of FIG. 7, respectively. Fig. 6 and Fig. 6A and Fig. 7 are the same developed sectional views along Figs.
FIG. 6B is a sectional view similar to FIG. 2 showing a star-shaped rotor type fluid distributor having the structure of FIG. 6B, and FIG. 8 is a schematic view showing the fluid distributor according to the present invention installed in a control circuit for a fluid motor. is there. A, A '... first variable diaphragm, B, B' ... second variable diaphragm, C,
C '... 1st fixed aperture, D, D' ... 2nd fixed aperture, E, E ₁ , E
₂ …… Distribution port, F, H, H ₁ , H ₂ …… Intermediate port, G …… Discharge port, I
...... central opening, O ...... inlet, R ...... low pressure tank, S ...... pressure source, V ...... fluid motor, V _1, V ₂ ...... working chamber, alpha, alpha '
...... fluid circuit 1 ...... input member, 2 ...... first distribution member or rotor, 3 ...... second distribution member, 5,5 _1, 5 ₂ ...... web portion, 6 ...... circular chamber, 7 ...... Stator.

Claims (1)

(57) [Claims] A pair of parallel circuits (α; α ′) is included between the pressure source (S) and the tank (R), each circuit including at least one first variable throttle (A; A ′) and at least one first variable throttle (A; A ′). Two variable diaphragms (B; B ') are arranged in series, and the variable diaphragms in the two circuits are opposed to each other and are connected to the corresponding circuit at an intermediate point between the paired first and second variable diaphragms. It is adapted to be actuated synchronously by the input member (1) so as to control a fluid motor (V) having a chamber (V ₁ ; V ₂ ), each circuit (α;
α ') is a first fixed throttle (C; C') which is activated alternately by the input member (1) in synchronization with the variable throttle downstream of the first variable throttle (A; A '). And the second fixed aperture (D;
D ') further comprising a fixed restrictor (C, D; C', D ') on each of the two distribution members (2, 3) in the radial direction. Concave surface (d)
A fluid distribution device for a vehicle power steering device, the fluid distribution device being formed by: 2. The first fixed throttle (C; C ') and the second fixed throttle (D; D') are activated at the downstream side of the second variable throttle (B; B ') of each circuit (α; α'). The fluid distribution device according to claim 1, wherein the fluid distribution device is configured as follows. 3. The first fixed diaphragm (C; C ') and the second fixed diaphragm (D; D') are the first variable diaphragm (A; A ') and the second variable diaphragm (B; B) of each circuit (α; α'). ′) Is operated in the downstream side, and the fixed throttle to be operated is located downstream of the variable throttle operated in the closing direction by the input member (1). The fluid distribution device according to claim 1, wherein 4. Variable diaphragm (A, B; A ′, B ′) and fixed diaphragm (C, D; C ′,
D ') ports (O, E, H, F, formed on the adjoining faces of two distribution members (2, 3) which can be displaced relative to each other on each side of the central position
Fluid distribution device according to any one of claims 1 to 3, characterized in that it is formed by the mutually cooperating edges of I). 5. At least one concave surface (d) of the fixed aperture of each circuit (α; α ′) extends between two adjacent mouths (H, I) of the corresponding distribution member (2) The fluid distribution device according to claim 4. 6. The concave surface (d ₁ ) of the first fixed aperture (C; C ') of each circuit (α; α') approaches the chamfered portion (l ₂ ) forming the second variable aperture (B; B ') of the above circuit. The fluid distribution device according to claim 4 or 5, wherein the fluid distribution device is formed as follows. 7. The fluid distribution device according to any one of claims 4 to 6, characterized in that the two distribution members (2, 3) are of a rotary type. 8. A fluid distribution device according to claim 7, characterized in that the adjacent surfaces of the distribution members (2, 3) are flat. 9. Claims, characterized in that the distribution member consists of a star-shaped rotor (2) housed in the circular chamber (6) of the stator (7), the concave surface (d) being formed in the rotor (2). The fluid distribution device according to item 8.