HYDRAULIC TORQUE IMPULSE GENERATOR WITH BYPASS MEANS

Abstract: A hydraulic torque impulse generator comprising a rotationally driven drive member (10; 50), a hydraulic fluid chamber (16; 51) confined in said drive member (10; 50), an output spindle (18; 53) having a rear impulse receiving portion (17; 52) extending into said fluid chamber (16; 51), at least two radially slidable vanes (23, 24; 58, 60) carried by said rear spindle portion (17; 52) and cooperating with corresponding seal portions (25, 26; 62, 63, 64) on the fluid chamber wall, axially extending seal ribs (29, 30; 65, 66, 67) on the fluid chamber wall and corresponding axially extending seal ribs (27, 28; 68, 70) on the rear spindle portion (17; 52). Simultaneous sealing cooperation is obtained more than once during each revolution of said drive member (10; 50) relative to said output spindle (18; 53), whereby said fluid chamber (16; 51) is momentarily divided into at least two high pressure compartments (H.P.) and at least two low pressure compartments (L.P.) A first passage means (32-35; 74-78) in said drive member (10; 50) cooperate with a second passage means (37, 38; 73) in said output spindle (18;53) to form bypass passages between said high pressure compartments (H.P.) and said low pressure compartments (L.P.) in all but one of the fluid chamber dividing positions, such that only one torque impulse per relative revolution between the drive member (10; 50) and the output spindle (18; 53) is generated.

Description: This invention relates to a hydraulic torque impulse generator of the type comprising a drive member coupled to a rotation motor, a substantially cylindrical fluid chamber confined in said drive member, an output spindle provided with a rear impulse receiving portion which extends into said fluid chamber, and at least two radially slidable vanes carried by said rear spindle portion and arranged to cooperate sealingly with corresponding seal portions on the wall of said fluid chamber, at least two axially extending seal ribs on the fluid chamber wall and at least two axially extending seal ribs on the rear spindle portion arranged to cooperate with said seal ribs on the fluid chamber wall, said vanes, seal portions and seal ribs being arranged to divide said fluid chamber during two or more limited intervals of each revolution of said drive member relative to said output spindle into at least two high pressure compartments and at least two low pressure compartments. The most important characteristic feature of this device, known from GB-A-2 136 719, is the location of the seal ribs, which has the purpose of preventing more than one torque impulse per revolution to be generated. This specific seal rib arrangement means that the axially directed seal ribs on the output spindle are located in a plane not extending through the rotation axis of the spindle, and that the seal ribs on the cylinder in a similar way are located in a plane not extending through the rotation axis of the cylinder. This means that there is obtained a sealing cooperation between the seal ribs on the output spindle and the seal ribs on the cylinder wall once only every relative revolution between the cylinder and the output spindle. Accordingly, one torque impulse only is generated per relative revolution. In contrast to this known device, our invention, which is defined in claim 1, comprises a bypass means which does not refer to the seal ribs on the output spindle and the cylinder wall. Instead, the seal ribs in the two-vane embodiment impulse generator according to our invention are in fact located symmetrically in planes extending through the common rotation axis of the cylinder and the output spindle, respectively, so as to accomplish a sealing action each half revolution between the cylinder and the output spindle. In order to accomplish a bypass function, the impulse generator according to the invention comprises a first passage means in one of the end walls of the cylinder and a second passage means in the output spindle. These passage means are arranged to form bypass passages to short circuit the high pressure and low pressure compartments every second occurance of a sealing cooperation between the vanes, the cylinder seal portions and the seal ribs. This is valid for a two-vane impulse generator. If, however, the number of vanes are three or more the bypass passage means in the end wall of the cylinder and in the output spindle are arranged to short circuit the high and low pressure compartments in all but one sealing position per relative revolution. On the drawings: Fig 1 shows a longitudinal section through an impulse generator according to one embodiment of the invention. Fig 2 shows a cross section along line II-II in Fig 1. Figs 3 and 4 show cross sections along line III-III in Fig 1 and illustrate different operation sequences. Fig 5 shows a longitudinal section through an impulse generator according to another embodiment of the invention. Fig 6 shows a cross section along line VI-VI in Fig 5. In the torque impulse generator shown in Figs 1-4 10 designates the drive member which via a socket portion 11 in a rear end wall 12 is connectable to a rotation motor. The rear end wall 12 is clamped by a ring nut 13 against an annular shoulder 15 in the drive member 10. The latter confines a substantially cylindrical fluid chamber 16 into which extends the rear portion 17 of an output spindle 18. The output spindle 18 is journalled on one hand in the central opening 19 of the forward end wall 14 of the fluid chamber 16 and on the other hand in a bore 21 in the rear end wall 12. To this end the spindle portion 17 is formed with a cylindrical rear extension 20 which is rotatively received in the bore 21. The spindle portion 17 is formed with a transverse through slot 22 in which two sliding vanes 23, 24 are supported in a diametrically opposed disposition. The vanes 23, 24 are arranged to cooperate sealingly with two diametrically opposed and axially extending seal portions 25, 26 on the fluid chamber wall. Such sealing cooperation occurs twice every relative revolution between the drive member 10 and the output spindle 18. Simultaneously with this sealing engagement two diametrically opposed seal ribs 27, 28 on the spindle portion 17 cooperate sealingly with two diametrically opposed seal ribs 29, 30 on the fluid chamber wall. The seal ribs 27, 28 on the spindle portion 17 are located at a 90° angular distance from the vanes 23, 24, and the seal ribs 29, 30 on the fluid chamber wall are disposed at a 90° angular distance from the seal portions 25, 26. In the rear end wall 12 there are four passages 32, 33, 34, 35 which at their one ends are open into the fluid chamber 16. At their opposite ends these passages are open into the bore 21. Two of these passages 32, 33 are open to the bore 21 in one common plane III-III transverse to the rotation axis of the spindle 18, whereas the other two passages 34, 35 are open to the bore 21 in another transverse plane IV-IV axially spaced from plane III-III. In the plane IV-IV the rear spindle extension 20 is formed with an arc-shaped slot 37 by which communication between the passages 32, 33 is controlled. In the plane III-III the spindle extension 20 has an arc-shaped slot 38 for controlling the communication between passages 34, 35. Slot 37 is located at a 180° angular distance from slot 38. In operation the drive member 10 is rotated in relation to the output spindle 18, and during two limited intervals of each revolution of the drive member 10 relative to the output spindle 18 there is obtained a sealing cooperation between vanes 23, 24 and seal portions 25, 26 as well as between seal ribs 27, 28 on spindle portion 17 and seal ribs 29, 30 on the drive member 10. During these two intervals, illustrated in Fig 3 and 4, the fluid chamber 16 is divided into two high pressure compartments H.P. and two low pressure compartments L.P. During one of these intervals the slot 37 interconnects the passages 33, 34, see Fig 3. At the same time the slot 38 interconnects the passages 32, 35. This means that the two high pressure compartments H.P. are shortcircuited to the low pressure compartments L.P. and that no pressure peaks are built up in the high pressure compartments H.P. Accordingly, no torque impulse is generated during this sequence. As the drive member 10 has rotated another 180°, see Fig 4, the seals of the drive member and the output spindle are again effective in dividing the fluid chamber 16 into high and low pressure compartments, H.P. and L.P. respectively. In this position, however, the slots 37, 38 are out of communication with the passages 32-35 in the drive member 10, which means that no bypass flow is obtained and that the high pressure compartments H.P. actually are sealed off from the low pressure compartments L.P. Pressure peaks are built up in the high pressure compartments H.P. and a torque impulse is generated in the output spindle 18. In the embodiment shown in Fig 5 and 6 a rotated drive member 50 comprises a fluid chamber 51 which is partly defined by a rear end wall 54 and into which a rear portion 52 of an output spindle 53 extends. The rear spindle portion 52 has three radial slots 55, 56, 57 which are distributed at equal angular distances and which support three radially slidable vanes 58, 59, 60. On the fluid chamber wall there are three seal portions 62, 63, 64 for sealing cooperation with the vanes 58, 59, 60. Since both the vanes and the fluid chamber seal portions are symmetrically located there is obtained a sealing cooperation therebetween during three limited intervals for each revolution of the drive member 50 relative to the output spindle 53. The drive member 50 also comprises three symmetrically disposed seal ribs 65, 66, 67 for sealing cooperation with three corresponding seal ribs 68, 69, 70 on the spindle portion 52. A concentric rear extension 71 on the output spindle 53 is sealingly rotated in a bore 72 in the rear end wall 54 and comprises a circumferential slot 73 which extends over a major part of the peripheri. The slot 73 is interrupted by a land 79. A part circular passage 74 in the rear end wall 54 interconnects three openings 75, 76, 77 which communicate with the three high pressure compartments H.P. A fourth opening 78 in end wall 54 opens into one of the three low pressure compartments L.P. The opening 78 communicates with the other two low pressure compartments L.P. via the vane slots 55, 56, 57. At rotation of the drive member 50 relative to the output spindle 53 the high pressure compartments H.P. will communicate with the low pressure compartments L.P. via the openings 75, 76, 77, the part circular passage 74, the circumferential slot 73, the opening 78 and the vane slots 55, 56, 57 during two of the three seal intervals. In the third interval, illustrated in Fig 6, the opening 78 blocked by the land 79 and, accordingly, it is out of communication with the slot 73. This means that no bypass is obtained and that a torque impulse is generated in the output spindle 53.

Claims: 1. Hydraulic torque impulse generator, comprising a drive member (10; 50) coupled to a rotation motor, a substantially cylindrical fluid chamber (16; 51) confined in said drive member (10; 50), an output spindle (18; 53) provided with a rear impulse receiving portion (17; 52) which extends into said fluid chamber (16; 51), at least two radially slidable vanes (23, 24; 58-60) carried by said rear spindle portion (17; 52) and arranged to cooperate sealingly with corresponding seal portions (25, 26; 62-64) on the wall of said fluid chamber (16; 51), at least two axially extending seal ribs (29, 30; 65-67) on the fluid chamber wall and at least two axially extending seal ribs (27, 28; 68-70) on the rear spindle portion (17; 52) arrranged to cooperate with said seal ribs (29, 30; 65-67) on the fluid chamber wall, said vanes (23, 24; 58-60), said seal portions (25, 26; 62-64) and said seal ribs (27-30; 65-70) being arranged to divide said fluid chamber (16; 51) during two or more limited intervals of each revolution of said drive member (10; 50) relative to said output spindle (18; 53) into at least two high pressure compartments (H.P.) and at least two low pressure compartments (L.P.), characterized in that a first passage means (32-35; 74-78) is located in one of the end walls (12; 54) of said fluid chamber (16; 51), and that a second passage means (37, 38; 73) is located in said output spindle (18; 53), said first and second passage means are separated structurally as well as functionally from said fluid chamber dividing vanes (23, 24; 58-60), seal portion (25, 26; 62-64) and seal ribs (27, 30; 65-70), and are arranged to be aligned and form bypass passages between said high pressure compartments (H.P.) and said low pressure compartments (L.P.) during all but one of said limited intervals of each revolution of said drive member (10; 50) relative to said output spindle (18; 53), thereby generating one torque impulse per revolution. 2. Impulse generator according to claim 1, wherein said first passage means (32-35; 74-78) is located in the rear end wall (12; 54) of said fluid chamber (16; 51) opening into a central axially extending bore (21; 72) in the latter, said second passage means (37, 38; 73) being located in a rear extension (20; 71) of said output spindle (18; 53), said extension (20; 71) being of cylindrical shape and being received in said bore (21; 72). 3. Impulse generator according to claims 1 or 2, wherein said vanes (23, 24) and the corresponding seal portions (25, 26) on the fluid chamber wall are two in number and arranged to cooperate sealingly during two limited intervals of each revolution of said drive member (10) relative to said output spindle (18), said first and second passage means (32-35, 37 38) being arranged to form bypass passages between said high pressure compartments (H.P.) and said low pressure compartments (L.P.) in one of said two intervals, thereby avoiding a torque impulse generation during that interval.

Inventors: SCHOEPS, KNUT CHRISTIAN, WESTERBERG, SVEN PETER JONAS
Applicants: ATLAS COPCO AKTIEBOLAG
Application year: 1987
Main classification: B25B21
IPC codes: B25B21, B25D15, F16D31