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(11) | EP 0 142 933 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Manual ratchet torque wrench with amplifier |
| (57) A manual ratchet torque wrench comprises a ratchet gear (55) turnably mounted in
a housing (50). The ratchet gear has a central portion (53) constructed to engage
a polygonal member of a threaded connector for turning the member upon turning of
the ratchet gear in one direction. An elongate handle (80) is connected to the housing
(50) for manually turning the housing in the one direction to turn the polygonal member
engaged by the central portion of the ratchet gear with a given force applied to the
handle. The wrench includes further a manually operated amplifier arrangement incorporated
in the housing for turning the ratchet gear in the one direction with a force greater
than the given force. This arrangement may include a manually operated pump (73, 58)
for pumping hydraulic fluid from a reservoir (89) into a pressure chamber (85a) defined
between one end of a cylinder (57) and an end face (60') of a piston (60) fluid-tightly
guided therein along a forward stroke and a return stroke, and a drive pawl (65) operatively
connected to the piston (60) which engages the teeth of the ratchet gear (55) to drive
the latter in the one direction during the forward stroke of the piston (60). A fluid
flow passage (95) between the pressure chamber (85a) and the reservoir (89), controlled
by a manually operated valve (97) between an open and a closed position, permits movement
of the piston (60) along the return stroke when the return flow passage (95) is opened. |
[0001] The present invention relates to a manual torque wrench and-more particularly to a manual torque wrench which can be advantageously used for tightening as well as for loosening threaded connectors, such as nuts mounted on bolts or studs. In the art, manual torque wrenches are used for precision tightening only and although they can be adjusted for clockwise and counter-clockwise ratcheting rotation, they are not meant for loosening applications, especially when those applications require a break- out torque in excess of the force achievable as the result of the leverage moment which in the art is determined by the length of the torque wrench.
[0002] The present invention seeks to provide a precision manual torque wrench which torque output is determined by the leverage length of the torque wrench and which is used for precision tightening of threaded connectors; and simultaneously a power wrench whose force output is a result of manual amplifier means and determined by the ratio of such means and which is used to loosen heavily corroded threaded connectors. The need for such a tool becomes obvious, especially on high pressure flange connections that develop a leak. To get the flange back in line requires first loosening of all fasteners usually at a considerably higher torque than is required to precision retighten them immediately thereafter. To accomplish this task, which up to now required the use of two different tools, with one single tool, is one of the aims of this invention.
[0003] It is further an aim of the present invention to provide a wrench by means of which a polygonal member of a threaded connector may be manually turned at high speed and precise torque by merely ratcheting the wrench manually and in which manually operated amplifier means are incorporated in the wrench for turning the polygonal member engaged thereby at a lower speed but at a force treater than can be applied by the mere leverage length.
[0004] It is further an aim of the present invention to provide a power tool to achieve the first break-loose moment of a threaded connector and to turn the threaded connector off at higher speed by using the wrench merely as a ratcheting wrench means.
[0005] What constitutes a wrench in accordance with the invention is defined in the following claim 1.
[0006] The housing of the wrench may comprise a first elongate housing portion extending along a first axis and a second housing portion extending transverse thereto on which the ratchet means is located.
[0007] The manually operated amplifier means may comprise a first cylinder bore formed in the first housing portion extending along the first axis and having an open end facing the second housing portion, piston means fluid tightly guided in the first cylinder bore for movement between a forward stroke toward the open end and a return stroke, the piston means having a rear face of a given area facing the other end of the first cylinder bore and forming therewith a pressure chamber, means including a drive pawl connected to the piston means distant from said rearface for turning the ratchet means in the one direction during the forward stroke of the piston means, and manually operated pumping means for pumping a hydraulic fluid into the pressure chamber for moving the piston means along its forward stroke.
[0008] The manually operated amplifier means preferably further includes a reservoir for a hydraulic fluid incorporated in the first housing portion, the manually operated pumping means then being arranged for pumping fluid from the reservoir into the pressure chamber.
[0009] The manually operated pumping means may comprise a second cylinder bore located in the first housing portion between the other end of the cylinder and the reservoir, and a pumping piston with an area smaller than the given area of aforementioned piston means to amplify the manual input force by the ratio between the two areas and increase the output torque on the ratchet means accordingly. The pumping piston can then be reciprocat- ably mounted in the second cylinder bore and may be operated by an elongate handle attached to the housing.
[0010] This arrangement may also include a return flow passage leading from the pressure chamber to the reservoir and manually operatable valve means in the return flow passage for opening and closing the latter.
[0011] The invention will now be further described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 shows the wrench partly in section in its lower part, the handle for operating the lower part being shown unsectioned in the upper part of Figure 1, and,
Figure 2 is a section on the line II-II in Figure 1.
[0012] Referring now to the drawings it will be seen that the wrench includes a housing generally designated 50 which comprises an elongate first housing portion 51 and a second housing portion 52 extending transverse thereto. The second housing portion 52 actually comprises two transversely spaced side plates; only one of which is shown in Figure 1, which are connected by welding or the like to one end of the first housing portion 51. A shaft 53 is turnably mounted in appropriate aligned bores of the two side plates forming the second housing portion 52 and this shaft extends with a square end portion 54 beyond one of the two side plates. A standard nut-engaging socket may be connected to the square end portion of the shaft 53 for engagement with a nut or the like polygonal -member of a threaded connector (not shown) to be turned by the wrench. A ratchet wheel 55 is centrally mounted on the shaft 53 for rotation therewith by being, for instance, connected by a key 56 thereto.
[0013] The first housing portion 51 is provided with an elongate stepped bore having an axis extending in the elongate direction of the first housing portion 51. This stepped bore comprises a first large-diameter portion 57 having an open end facing the second housing portion 52, a second, small-diameter portion 58 coaxial therewith and a third, large-dimeter portion 59 coaxial with and communicating with the second, small-diameter portion 58 and having an open end at the other end of the first housing portion 51.
[0014] A driving piston 60 sealed by a sealing ring 61 is slidingly arranged in the first, large-diameter portion 57 of the stepped bore and can move between an active forward stroke towards the right, as viewed in Figure 1, and an oppositely directed return stroke. A short piston rod 62 projects from the right end face, as viewed in Figure 1, of the piston 60 and the right end of the piston rod 62 is bifurcated, so that the left end of a member 63 sandwiched between the bifurcated end of the piston rod 62 may be pivotally connected by a first pivot pin 64 to the piston rod 62. The other end of the member 63 is likewise bifurcated, and a pawl 65 is connected to this bifurcated end of the member 63 by a second pivot pin 66. The pivot pin 66 connects also the upper ends of a pair of arms 67 (only one of which is shown) located on opposite sides of the central ratchet wheel 55 between the side plates formed by the second housing portion 52 and the lower ends of these arms 67 are turnably mounted on the shaft 53.
[0015] During reciprocation of the driving piston 60, the pivot pin 66 and therewith the pawl 65 is thereby guided along a circular arc about the axis of the ratchet wheel 55. A leaf spring 68, connected, for instance, by a screw 69 to one of the arms 67, engages' the pawl 65 to maintain the latter in engagement with the teeth of the ratchet wheel 55 during the forward stroke of the driving piston 60.
[0016] . A cap 70 extends over the left end, as viewed in Figure 1, of the first housing portion 51 releasably connected thereto by a screw 71 or the like. The cap is formed with a central opening 72 through which an elongate pumping piston 73 extends. The right end of the pumping piston 73 extends into the second, small-diameter portion 58 of the stepped bore. The left end, as viewed in Figure 1, of the piston 73 is screwed into a transverse pin 74, and opposite ends of this pin 74 extend through elongate slots 75 in a bifurcated handle portion 76 extending at an angle oc to the axis of the piston 73. The bifurcated handle portion 76 extends between a pair of transversely spaced guide plates 77 (see also Figure 2) which project parallel to each other from the cap 70 in the direction of the elongate pumping piston 73. Each of these guide plates 77 is formed in its lower end portion with an elongate slot 78 extending substantially in the same direction as the slots 75. A pin 79 carried by the lower end of the bifurcated handle portion 76 parallel to the transverse pin 74 extends into the slots 78 in the guide plates 77. The handle of the wrench also includes an elongate operating portion 80 adapted to be manually gripped by an operator during use of the wrench, and this elongate operating portion extends transverse to the above described bifurcated handle portion 76 substantially parallel to the elongate pumping piston 73 and preferably consists of two parts, that is a tubular portion 81 connected in any suitable manner to the upper end of the handle portion 76, and a rod-shaped portion 82 slidably received in the tubular portion 81 to be extended or collapsed with respect thereto and the rod-shaped portion 82 may be held in the' extended or collapsed position by spring-pressed balls 83 of standard construction and thus only schematically indicated in Figure 1.
[0017] The handle components 76, 80 may be locked in the position as shown in Figure 1 by a locking member 84 which traverses, with a bifurcated end portion, the elon- gate pumping piston 73 and which is tightly sandwiched between the left end face of the cap 70 and a ring member 85 fixed to the elongate pumping piston 73. If the locking member 84 is in the position shown in full lines in Figure 1, and the driving piston 60 engages the left end of the first, large-diameter portion 57 of the stepped bore, the handle 80 may be manually turned in the clockwise direction as indicated by the arrow a to thereby turn the housing 50 together with the ratchet wheel 55 about the axis of the latter, so that a nut or the like engaged in the socket connected to the square end portion 54 of the shaft 53 may be turned in the same direction and with a force as applied by the operator to the handle portion 80.
[0018] If this force applied by the operator should not be sufficient to tighten the nut to the desired degree, or to loosen a partly corroded nut, then the manually operated hydraulic amplifier means incorporated in the first housing portion 51 can be used.
[0019] The manually operated hydraulic amplifier means comprises the already-described piston 60 reciprocatable in the first, large-diameter portion 57 of the stepped bore, which piston 60 drives, during its forward stroke, the ratchet wheel 55 about its axis and manually operated pumping means, that is the already-described elongate pumping piston 73 reciprocatable in the second, small-diameter portion 58 of the stepped bore for pumping a hydraulic fluid into a pressure chamber 85a defined between the rear face 60' of the piston 60 and the junction of the first, large-diameter portion and the second, small-diameter portion 58 of the stepped bore. A first one-way valve 86 is arranged at the end of the small-diameter bore portion 58 facing the pressure chamber 85a,=.and this one-way valve 86, which is of standard construction comprising a spring-pressed ball, is constructed to permit flow of fluid only from the cylinder bore 58 into the pressure chamber 85a while preventing fluid flow in the opposite direction.
[0020] Upstream of the one-way valve 86, the cylinder bore 58 communicates also with one end of a suction passage 87 which communicates at the other end, via a second one-way valve 88, with a fluid reservoir 89 formed by part of the third, large-diameter bore portion 59 and closed at its rear end by a piston 90 slidingly arranged in the large bore portion 59 and sealed thereto by a sealing ring 91. The pumping piston 73 extends through a central bore 92 of the sliding piston 90 and is sealed by a sealing ring 93. A helical compression spring 94 arranged in the fluid reservoir 89 biases the sliding piston 90 towards the cap 70. The second one-way valve 88, constructed in the same manner as the first one-way valve 86, is arranged to permit fluid flow from the reservoir 89 into- the suction passage 87 while preventing fluid flow in the reverse direction. A return flow passage 95 communicates at one end with the pressure chamber 85a and at the other end with the reservoir 89. A third one-way valve 96 is arranged at the other end of the return flow passage 95, and this third one-way valve 96, constructed as the other one-way valves, permits flow of fluid only from the reservoir 89 into the return flow passage 95 while normally preventing flow in the opposite direction. This third one-way valve 96 may, however, be opened, for a purpose which will be described further below, by a manually actuatable operating member 97 comprising an elongate rod extending through a second bore 98 in the sliding piston 90 properly sealed by a sealing ring 99. The operating member 97 has a portion 97' extending through a slot 100 in the first housing portion 51 to the outside and over the latter and a spring-pressed ball lock 101 of standard construction, arranged in the portion 97' of the operating member 97, permits the same to be locked in the position shown in Figure 1 or in an advanced position towards the right, as viewed in Figure 1, in which a pointed end 97" of the operating member 97 engages the ball of the third one-way valve 96, thereby preventing valve action and permitting flow to occur from the pressure chamber 85a via the return flow passage 95 into the reservoir 89. A ring 102 fixed to the operating member 97 engages the rear face of the sliding piston 90, limiting movement of the latter, under the influence of the compression spring 94, towards the cap 70. A gauge 103 of standard construction communicates with the return flow passage 95 and thus with the pressure chamber 85a to indicate the pressure prevailing therein and the gauge 103 can have its scale graduated to indicate directly the torque applied by the wrench since this will be related to the pressure created in the pressure chamber 85a during operation of the manually operated pumping means of the wrench.
[0021] The above described embodiment of the self-contained hydraulic wrench of the present invention may be operated as follows:
At first, the handle locking member 84 is moved to the position as shown in full lines in Fig. 1, and then the handle 80 is gripped by the operator and moved in the direction indicated by the arrow a thereby turning the housing means 50 together with the ratchet 55 about the axis of the latter, so that a nut, or the like, engaged in a socket connected to the square end portion of the shaft 53 is turned by a force as applied by the operator to the handle. The driving piston 60 is thereby in its starting position as shown in Figure 1. The wrench can be operated in .this way like- any simple manually operated box wrench.
[0022] If the force applied by the operator to the handle 80 is not sufficient to tighten the nut to the desired degree, then further turning of the nut is accomplished by the manually operated hydraulic amplifier means and to bring this into effect the handle locking member 84 is first moved into the position shown in dotted lines in Figure 1 so that the pumping piston 73 is free to be reciprocated by the handle 76, 80.
[0023] When the handle 80 is now moved in the direction of the arrow a, it will cause the pumping piston 73 to make a pumping stroke. If, prior to making a pumping stroke, the handle portion 76 is moved in a downward direction so that the pin 79 moves to the lower ends of the slots 78 in the guide plates 77, while the transverse pin 74 connected to the rear end of the pumping piston 73 moves to the upper ends of the slots 75 in the handle portion 76, the pumping piston during 73 will undertake a relatively large stroke. During this forward stroke of the pumping piston 73, fluid is expelled from the bore 58 through the first one-way valve 86 into the pressure chamber 85a, forcing the piston 60 to move towards the right and thereby turning the ratchet wheel 55 and the shaft 53 in a clockwise direction to tighten the nut further. During the rearward stroke of the pumping piston 73, fluid will pass from the reservoir 89 through the second one-way valve 88 and the suction passage 87 into the bore 58. Thus the piston 90 moves against the force of the compression spring 94 to the right end, as viewed in Figure 1, of the reservoir 89. This action is repeated until the piston 60 engages an abutment 104 at the other end of the large bore portion 57 and the sliding piston 90 engages an abutment 105 on the operating member 97. Thereafter, the operating member 97 is moved to its forward position, until the pointed end 97" thereof displaces the ball of the third one-way valve 96 to open the latter. Fluid may now flow from the pressure chamber 85a through the return passage 95 into the reservoir 89, allowing the spring 94 to push the sliding piston 90 rearwardly until it again engages the abutment ring 102 on the operating member 97. This creates a vacuum in the pressure chamber 85a which in turn moves the driving piston 60 back to its starting position as shown in Figure 1, causing the pawl 65 to ratchet over the teeth of the ratchet gear 55. If the nut should not be tightened sufficiently during the afore-described operation, then the handle portion 76 can be moved back to the position shown in Figure 1, so that the sliding piston 73 during the next tilting of the handle 80 under the same manual force, is moved with a smaller stroke but under the influence of a greater effective force during reciprocation of the handle 80.
[0024] If a nut engaged in a socket connected to the square end portion 54 of the shaft 53 should be turned in its loosening direction, it may happen that the cooperating threads of the nut and the bolt engaged therein may be corroded, so that the force applied by the operator to the handle 80 may not be sufficient to loosen the nut. In this case the nut can be loosened by first operating the amplifier means in the manner described above, and after breaking the nut loose it may be further unscrewed by turning the ratchet 63 directly via the handle 80 without utilising the amplifier means.
[0025] The wrench illustrated also includes a plate-shaped abutment member 106 connected by a screw bolt 107 to the bottom face of the first housing portion 51. A plurality of pins 108 arranged circumferentially spaced from each other along a circle concentric with the axis of the screw bolt 107 permits the position of the abutment member 106 to be adjusted to extend either along the bottom face of the first housing portion 51 or downwardly therefrom in the direction of the shaft 53. During turning of the housing 50 together with the ratchet wheel 55 about the axis of the latter by the handle 80, the plate-shaped abutment member 106 is maintained in the position shown in Figure 1 extending along the bottom face of the first housing portion 51. However, during operation of the hydraulic amplifier means and turning of the ratchet wheel 55 relative to the housing 50 the plate-shaped abutment member 106 can be turned to extend downwardly from the housing 50 in the direction of the axis of the ratchet wheel 55 to abut against a stationary abutment- (not shown) to counteract the force created during oepration of the manually operated pumping means.
1. A manual ratchet torque wrench comprising a housing (50), ratchet means (55) mounted
in said housing (50) turnable about an axis (53), means for engaging a polygonal member
of a threaded connector for turning the member upon turning of said ratchet means
(55) in one direction, an elongate handle (80) on said housing (50) for manually turning
said housing (50) together with said ratchet means (55) in said one direction about
said axis (53) so as to turn a polygonal member engaged by said means on said ratchet
means with a given force, characterised in that manually operated amplifier means
(60, 58, 73, 76) is incorporated in said housing (50) for turning said ratchet means
(55) and said means thereon relative to said housing (50) in said one direction with
a force greater than said given force.
2. A wrench as claimed in claim 1, characterised in that the housing (50) comprises
a first, elongate housing portion (51) extending along a first axis and a second housing
portion (52) extending transverse thereto, the ratchet means (55) being located in
the second housing portion (52) turnable about a second axis normal to the first axis.
3. A wrench as claimed in claim 1 or claim 2, characterised in that the manually operated
hydraulic amplifier means comprising a first cylinder bore (57) formed in the housing
(50), a piston (60) fluid-tightly guided in the first cylinder bore (57) for movement
forwards and backwards therein, the piston (60) having a rear face (60') facing a
substantially closed end of the first cylinder bore (57) and forming therewith a pressure
chamber (85a), means 462, 63, 64) including a drive pawl (65) connected to the piston
(60) for turning the ratchet means (55) in one direction during a forward stroke of
the piston (60), and manually operable pumping means (80, 76, 73) for pumping a hydraulic
fluid into the pressure chamber (85a) for moving the piston (60) along its forward
stroke.
4. A wrench as claimed in claim 3, characterised in that it includes a reservoir (89)
for a hydraulic fluid incorporated in the housing (50), the manually operable pumping
means (80, 76, 73) being arranged for pumping fluid from the reservoir (89) into the
pressure chamber (85a).
5. A wrench as claimed in claim 4, characterised in that the manually operated pumping
means (80, 76, 73) comprises a second cylinder bore (58) located in the housing (50)
between the pressure chamber (85a) and the reservoir (89), a pumping piston (73) reciprocatable
in the second cylinder bore (58), and means (80, 76, 75, 74) for reciprocating the
pumping piston (73).
6. A wrench as claimed in claim 5, characterised in that the second cylinder bore
(58) communicates via a first one-way valve (86) with the pressure chamber (85a),
the first one-way valve (86) permitting only flow from the second cylinder bore (58)
into the pressure chamber (85a), a suction passage (87) providing communication between
the reservoir (89) and the second cylinder bore (58) upstream of the first one-way
valve (86), and a second one-way valve (88) in the suction passage (87) permitting
only flow from the reservoir (89) into the second cylinder bore (58).
7. A wrench as claimed in claim 6, characterised in that a return flow passage (95)
leading from the pressure chamber (85a) to the reservoir (89) is provided and in that
a manually operable valve (97", 96) is provided in the return flow passage (95) for
controlling fluid flow therethrough.
8. A wrench as claimed in claim 7, characterised in that the return flow passage (95)
communicates with one end of the reservoir (89) and includes a sliding piston (90)
fluid-tightly guided in the reservoir (89) and movable from the opposite end of the
latter towards said one end during pumping of hydraulic fluid from. the reservoir
(89) into the pressure chamber (85a) to prevent creation of a vacuum between the one
end of the reservoir (89) and the sliding piston (90).
9. A wrench as claimed in claim 8, characterised in that spring means (94) is provided
biasing the sliding piston (90) towards the opposite end of the reservoir (89) to
enhance return flow of fluid from the pressure chamber (85a) to the reservoir (89)
when the return flow passage (95) is opened.
10. A wrench as claimed in claim 8 or claim 9, characterised in that the second cylinder
bore (58) extends in the direction of an axis of the housing (50), the reservoir (89)
being formed by a third cylinder bore (59) in the housing (50) substantially coaxial
with the second cylinder bore (58) and the pumping piston (73) extends in a sealed
manner through the sliding piston (90) and with an end portion thereof extending outside
the third cylinder bore (59).
11. A wrench as claimed in any one of claims 5 to 10, characterised in that mounting
means (76) is provided on one end of the housing (50) for mounting an end of a handle
(80) pivotable about a pivot axis (79) spaced from and normal to the axis of the housing
(50), an end of the pumping piston (73) being connected to the mounting means (76)
spaced from the pivot axis (79) so that upon pivoting the handle (80) about the pivot
axis (79), the pumping piston (73) will be reciprocated, and handle locking means
(84) movable from a first position preventing pivoting of the handle (80) about the
pivot axis (79) so that the handle (80) may be used for turning the housing (50) together
with the ratchet means (55) about the axis of the latter and a second position freeing
the handle (80) to pivot about the pivot axis (79) to thereby reciprocate the pumping
piston (73).
12. A self-contained hydraulic wrench as claimed in claim 11, characterised in that
mean5 (74, 75: 78, 79) is provided on the mounting means (76) and the handle (80)
for changing the length of the stroke of the pumping piston (73) while pivoting of
the handle (80) through a given angle (oc) about the pivot axis (79).
13. A wrench as claimed in any preceding claim, characterised in that a gauge (103)
is provided communicating with the pressure chamber (85a), the gauge (103) having
a scale indicating the torque applied to a threaded connector in correspondence to
the pressure existing in the pressure chamber (85a).
14. A wrench as claimed in claim 5 or any claim dependent thereon, characterised in
that the second cylinder bore (58) has a cross section considerably smaller than the
cross section of the first cylinder bore (57).
15. A wrench as claimed in any preceding claim, characterised in that abutment means
(106) is provided on the housing (50) which is adapted to engage a fixed abutment
during operation of the wrench by the manually operated amplifier means (60, 58, 73,
76) to counteract the force created during this operation tending to turn the housing
(50) about the turning axis of the ratchet means (55).
16. A wrench as claimed in claim 15, characterised in that the abutment means (106)
is plate-shaped and includes means (107, 108) to attach the plate-shaped abutment
means (106) at different angular positions to the housing (50).