GB2463498A

GB2463498A - Lockable clamp

Info

Publication number: GB2463498A
Application number: GB0816884A
Authority: GB
Inventors: Grahame David Bannister
Original assignee: Eschmann Holdings Ltd
Current assignee: Eschmann Holdings Ltd
Priority date: 2008-09-16
Filing date: 2008-09-16
Publication date: 2010-03-17
Also published as: GB0816884D0

Abstract

A clamp 104 comprises rotatable element having ball 108, clamp housing 12 containing ball 108, and a handle 144. Housing has annular seat 110 upon which ball is selectively rotatable, opposed through-holes 114 for receiving elongate element 106, and toggle mechanism 120. Handle 144 moves toggle 120 from a biased unlocked position in which ball 108 and elongate member 106 are movable, to a second locked position in which ball 108 is clamped by first part 130 of toggle 120 and elongate member 106 is clamped by second part 150. Toggle parts 120,150 may be pivotable relative to each other, and may each have a pivot arm 1341 152. Pivot arm 152 may be operable by handle 144, and pivot arm 134 may be biased by biasing member 122. Pivot arm 134 may have a stop surface 137 to limit the action of the biasing member 122. Pivot arm 152 may have a stop surface 156 for preventing the toggle 120 going into an over-centre position. Pivot aims 134, 152 may have alignment surfaces 138, 157 that engage in the unlocked position. Pivot arm 152 may have an urging surface 153 for handle 144 to engage. Clamp 104 is for use on a surgical table.

Description

CLAMP

[0011 The present invention relates to a lockable clamp, in particular a lockable clamp adapted to mount an accessory to a surgical table in a selected orientation.

[002] It is well known to provide surgical tables with various types of accessory which are intended to be removably fitted to the table dependent on the needs of a surgeon and the patient. Such accessories typically comprise arm or leg supports which extend outwardly from the table surface for supporting the limbs of a patient during a surgical procedure. Other types of accessory are also known. Such accessories need to be removably fitted to the surgical table, and also orientable into a number of different positions, dependent on the requirements of the particular patient.

[003] Various types of clamp are known for locking the accessory in the selected orientation. The clamp is required to lock the position of the accessory in such a manner that the accessory does not inadvertently move from that position during the surgical procedure. Some clamps are required to lock both the translational and rotational positions of the accessory. This locking should ideally be achieved without requiring the medical personnel to use high manual forces when locking the clamp in a particular configuration. The clamp for the accessories should exhibit versatility to enable a variety of different accessories to be fitted in a wide variety of different configurations. Furthermore the clamp should be of a construction to permit a variety of different styles and types of rigid fixtures to be fitted to the clamp.

[004] A known clamp is described in GB2410289A. This clamp comprises a housing for a floating wedge clamp for clamping an accessory bar for supporting an accessory relative to a mounting element for mounting the clamp to a surgical table, for example. The floating wedge clamp has been found to have a problem that it tends to distort the accessory bar such that the wedge becomes trapped making the clamp stick in a locked position even when released.

[005] A way of ameliorating these problems has been sought.

[006] According to the invention there is provided a clamp which has: a rotatable element having a ball; a clamp housing which at least partially contains the ball; and a handle; wherein the housing has: an annular seat for the ball such that the ball is selectively rotatable on the seat; opposed through-holes for receiving an elongate element; and a toggle mechanism having a first part having a clamp for engaging the ball and a second part having a clamp for engaging the elongate element; wherein the handle is operable to move the two parts of the toggle mechanism from a first unlocked position where the rotatable element and the elongate element are movable to a second locked position where the rotatable element and elongate element are clamped; and wherein the toggle mechanism is biased to the first unlocked position.

[007] The advantages of the present invention include that as the locking mechanism in the clamp comprises a toggle mechanism, the risk of the clamp sticking in a locked position is minimised. This is because in the operation of the toggle mechanism, any force applied by the handle to the toggle mechanism or by the biasing of the toggle mechanism is magnified considerably. Accordingly, when the handle is released from the toggle mechanism, there is a considerable release of pressure on the rotatable element and the elongate element such that there is no risk of either element not being released from the clamp.

[008] In some embodiments, the rotatable element may be a mounting element for mounting the clamp to a surgical table. In some embodiments, the elongate element may be provided with an accessory for a surgical table. The elongate element may be an accessory bar.

[009] In the unlocked position of the clamp, the rotatable element and the elongate element are selectively movable relative to one another. In the locked position of the clamp, the elongate element may be clamped in position by the second clamp pressing the elongate element against the opposed through-holes.

[0010] In some embodiments, the handle has an actuation member and the housing has an opening for receiving the actuation member for engaging an urging surface of the toggle mechanism to move the toggle mechanism from the first position to the second position.

[0011] In some embodiments, the clamp has a biasing member for biasing the toggle mechanism from the second position to the first position when actuation member is released from the urging surface. The biasing member may be a compression spring.

[0012] In some embodiments, the first and second parts of the toggle mechanism are pivotable relative to each other. The pivoting surface of the toggle mechanism may be rounded such that it is a rolling pivot. An advantage of a pivot is that it does not have to be greased. Grease can be a problem to a clamp according to the invention because if it contacts the ball and/or the elongate element, it can reduce the surface friction of the clamp making it more difficult to operate.

[0013] In some embodiments, each of the first and second parts of the toggle mechanism has a pivot arm. One pivot arm may be an actionable pivot arm which is operable by the handle or is acted on by a part of the handle, e.g. the actuation member which may be a bolt threaded through an aperture formed in the housing. The actionable arm may have an urging surface for the handle (or a part of the handle) to engage. The other pivot arm may be a biased pivot arm which is biased by a biasing member.

[0014] In some embodiments, the biased pivot arm has a stop surface for engaging the part of the toggle mechanism having the actionable pivot arm so as to limit the action of the biasing member when the toggle mechanism is in the first position. The biasing member may be arranged to engage an outer surface of the biased pivot arm.

[0015] In some embodiments, the actionable pivot arm has a stop surface for engaging the part of the toggle mechanism having the biased pivot arm so as to prevent the toggle mechanism going into an over-centre position when the toggle mechanism is in the second position. An advantage of this feature is that it prevents the elongate element and/or the ball from being damaged by the clamp being over-tightened in a locked position.

[0016] In some embodiments, the actionable and biased pivot arms each have an alignment surface which surfaces engage each other in the first position of the toggle mechanism. An advantage of this feature is that it provides a simple mechanism for locating and aligning the two parts of the toggle mechanism in the clamp housing.

[0017] In some embodiments, the actionable pivot arm has a pivot which is formed between the alignment and stop surfaces of the actionable pivot arm, preferably the pivot is formed to have an angle of from 75° to 900.

The difference between this angle and the angle of between the alignment surface of the biased pivot arm and the surface of its clamp defines the degree of movement of the toggle mechanism. The magnitude of this difference may easily be determined by a person of skill in the art.

[00181 In some embodiments, the second part of the toggle mechanism has a formation for engaging with a corresponding formation on the clamp housing for limiting the movement of the second part in the clamp housing. An advantage of this feature is that the floating second part is held in position when an elongate element is not present.

[0019] In some embodiments, the clamp of the first part has a concave surface for engaging the ball. In some embodiments, the clamp of the second part has a through-hole for receiving the elongate element.

[0020] According to the invention, there is further provided a kit comprising a clamp according to the invention and one or more elongate elements.

[0021] An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a perspective view of a clamp in accordance with the present invention; Figure 2 shows a perspective view of the clamp of Figure 1 fitted with an accessory for a surgical table; Figure 3 shows an enlarged perspective view of the assembly of the clamp and accessory of Figure 2; Figure 4 shows a schematic sectional view through the clamp and accessory shown in Figures 1 to 3 in a first position; and Figure 5 shows a schematic sectional view through the clamp and accessory shown in Figures 1 to 3 in a second position.

[0022] Referring to Figures 1 to 5, these figures show a surgical accessory clamp, in the form of a ball-locking clamp assembly, in accordance with an embodiment of the present invention.

[0023] The external structure of the clamp assembly of the embodiment of the present invention is shown in Figure 1, and Figures 2 and 3 show the clamp assembly of Figure 1 in combination with an accessory bar assembled therewith. The ball locking clamp assembly, designated generally as 100, comprises a mounting element 102, for mounting on a surgical table (not shown) and a clamp 104 fitted to the mounting element 102. The clamp 104, in use, supports an accessory bar 106 to which is attached an accessory 107, such as a limb support. The accessory bar 106 is thus an elongate element. The mounting element 102 is provided at one end with a spherical ball 108 which fits in the clamp 104 on an annular part-spherical seat 110. The mounting element 102 is thus a rotatable element. The ball 108 is captive in a housing 112 of the clamp 104. The ball 108, can, when the clamp 104 is unlocked, be rotated on the seat 110 so that the clamp 104 can be disposed in a selected angular orientation with respect to the mounting element 102. The accessory bar 106 extends through the housing 112 of the clamp 104 between two opposed through-holes 114 in the housing 112. When the clamp 104 is unlocked, the accessory bar 106 can be slid translationally relative to the clamp 104. In this way, when the clamp 104 is unlocked, the accessory 107 mounted on the remote end of the accessory bar 106 can be disposed in a selected rotational and translational position with respect to a surgical

table.

[0024] When the clamp 104 is locked, the clamp 104 is rotationally locked relative to the mounting element 102 and the accessory bar 106 is translationally locked relative to the clamp 104. The locking and unlocking of the clamp 104 is achieved by rotation, in the respective angular direction, of a handle 144 fitted to the clamp 104. The operation of the handle 114 commonly locks and unlocks both the clamp 104 to the mounting element 102 and the accessory bar 106 to the clamp 104.

[00251 The internal structure of the clamp assembly of the embodiment of the present invention is shown in Figures 4 and 5. The ball 108 of the mounting element 102 is received in the annular cylindrical outer housing 112 of the clamp 104 which defines the annular part-spherical seat 110 for the ball 108. The seat 110 is located on the same side of the centre of the ball 108 as that of the mounting element 102 whereby the ball 108 is held captive by the seat 110 within the outer housing 112 of the clamp 104. The pair of opposed through-holes 114 are provided on opposite sides of the outer housing 112 through which the accessory bar 106 extends along a pathway 115 in a direction orthogonal to the axis of the outer housing 112.

[0026] Clamp 104 has a two part toggle mechanism indicated generally at 120, which is disposed in the housing 112. The toggle mechanism 120 has an unlocked position shown in Figure 4 and a locked position shown in Figure 5. The toggle mechanism 120 has a floating first L-shaped proximal part indicated generally at 130 which is located next to the mounting element 102, a floating second q-shaped distal part indicated generally at 150 and a biasing member 122 in the form of a compression spring. The L-shaped proximal part 130 of the toggle mechanism 120 has a proximal clamp 132 and a distal upright elongate pivot arm 134. The upright pivot arm 134 is a biased pivot arm. The q-shaped part 150 of the toggle mechanism 120 has a proximal tail elongate pivot arm 152 and a distal clamp 154. The tail pivot arm 152 is an actionable pivot arm. In an alternative embodiment, the L-shaped part 130 has an actionable pivot arm and the q-shaped part 150 has a biased pivot arm.

[0027] The upright pivot arm 134 of the L-shaped proximal part 130 is engaged by the tail pivot arm 152 of the q-shaped distal part 150. The spring 122 is mounted on the interior surface 113 of the housing 112 to engage an outer surface 135 of the upright pivot arm 134 of L-shaped part such that the spring 122 biases the toggle mechanism 120 intO an unlocked position.

[0028] The upright pivot arm 134 of the L-shaped proximal part 130 has an upper surface 137 which engages with a lower surface 155 of the distal clamp 154 to limit the relative movement of the toggle mechanism 120 into an unlocked position.

[0029] The tail pivot arm 152 of the q-shaped distal part 150 has an outer surface on which an urging face 153 is provided. Tail pivot arm 152 has a lower surface 156 which when the toggle mechanism is in a locked position, engages and forces proximal clamp 132 against ball 108 and prevents the toggle mechanism from going into an over-centre position.

Tail pivot arm 152 also has an inner alignment surface 157 which engages inner alignment surface 138 of upright pivot arm 134 to assist in the alignment of the toggle mechanism 120 in the unlocked position. Tail pivot arm 152 has a rounded pivot 159 where lower surface 156 and inner alignment surface 157 meet such that rounded pivot 159 is a rolling pivot.

The angle between lower surface 156 and inner alignment surface 157 at pivot 159 is less than 90° and is about 88°. Pivot 159 engages the join where upright pivot arm 134 meets proximal clamp 132 of L-shaped proximal part 130. The angle between alignment surface 138 and proximal clamp 132 at the join where upright pivot arm 134 meets proximal clamp 132 of L-shaped proximal part 130 is greater than 90° and is about 110°.

[00301 The proximal clamp 132 of L-shaped part 130 has a part-spherical concave surface 136 which is provided to mate with the ball 108.

[0031] Distal clamp 154 has a cavity 158 extending therethrough, the cavity 158 partially defining the pathway 115 for receiving the accessory bar 106. Cavity 158 is substantially oval and has a principal axis which is longer than the diameter of accessory bar 106 so that accessory bar 106 can be easily moved relative to distal clamp 154 when toggle mechanism is in an unlocked position.

[0032] Accessory bar 106 assists in holding floating q-shaped part 150 in place. When accessory bar 106 is not present, q-shaped part 150 is prevented from rotating and occluding through-holes 114 by a grub screw 116 inserted through housing 112 to engage a recess 151 formed in distal clamp 154.

[0033] A threaded hole 117 is provided in the outer housing 112 and a threaded bolt 118 extends through the threaded hole 117 whereby one end 119 of the bolt 118 is disposed against the urging face 153 of the tail section of the q-shaped part. The cavity 158 defining the pathway 115 which, in use, receives the accessory bar 106 is laterally spaced from the rotational axis of the threaded bolt 118. A manually operable handle 144 is provided at the other end of the threaded bolt 118. The manually operable handle 144 is elongate. The handle 144 has an integrally moulded leaf spring 146 for biasing the elongate handle at least to a position orthogonal to the rotational axis of the threaded bolt 118.

[0034] A cover member 165 is fitted into the end of the housing 112 remote from the ball 108 so as to inhibit or prevent bacteria or infection from entering the housing 112.

[0035] When it is desired to lock the accessory in the selected rotational and translational orientation relative to the surgical table, the accessory bar 106 is translationally slid to the desired translational position relative to the clamp 104 and the clamp 104 is angularly rotated to a desired rotational configuration relative to the mounting element 102. The threaded bolt 118 is then rotated, by rotating the handle 144, so as to be screwed into the threaded hole 117 and urged against the urging face 153 of the tail pivot arm 152 of the q-shaped distal part 150.

[0036] The q-shaped distal part 150 and the L-shaped proximal part 130 are also urged apart by the action of tail pivot arm 152 as it pivots from a position where alignment surfaces 138,157 are engaged to a position where lower surface 156 of tail pivot arm 152 engages proximal clamp 132. When the q-shaped distal part 150 and the L-shaped proximal part are urged apart in the locked position of the toggle mechanism 120, distal part 150 locks accessory bar 106 by pressurising the accessory bar 106 against the housing 112 and proximal part 130 locks ball 108 against seat 110. The toggle mechanism 120 is prevented from going into an over-centre position by the lower surface 156 of tail pivot arm 152 engaging proximal clamp 132 in a locked position of the toggle mechanism 120, [0037] The clamp 104 is unlocked by rotating the handle 144 in an opposite direction so as to release bolt 118 from exerting pressure on the urging face 153 of the tail pivot arm 152. Spring 122 returns the toggle mechanism back into an unlocked position by urging upright pivot arm 134 against tail pivot arm 152. The ball-locking clamp assembly of the present invention exhibits a number of advantages.

[0038] The present invention ensures that as the clamp is released the accessory bar 106 and ball 108 are released completely.

[0039] On release, the distal clamp 154 drops away from the accessory bar 106 ensuring that the accessory bar 106 is released cleanly and completely without sticking.

[0040] As the clamp 104 is based on a toggle mechanism, the force applied by handle 144 is magnified considerably, thereby ensuring that the clamp 104 is extremely secure.

[0041] Although the two main components, the distal part 150 and proximal part 130, pivot against each other, there is no requirement for them to be greased, as the pivot 159 has a rolling action, rather than a sliding action. This lack of grease means that there is no possibility that grease can get onto ball 108 or accessory bar 106 and reduce the surface friction of the clamp 104.

Claims

CLAIMS1. A clamp which has: a rotatable element having a ball; a clamp housing which at least partially contains the ball; and a handle; wherein the housing has: an annular seat for the ball such that the ball is selectively rotatable on the seat; opposed through-holes for receiving an elongate element; and a toggle mechanism having a first part having a clamp for engaging the ball and a second part having a clamp for engaging the elongate element; wherein the handle is operable to move the two parts of the toggle mechanism from a first unlocked position where the rotatable element and the elongate element are movable to a second locked position where the rotatable element and elongate element are clamped; and wherein the toggle mechanism is biased to the first unlocked position.
2. The clamp as defined in Claim 1 wherein the first and second parts of the toggle mechanism are pivotable relative to each other.
3. The clamp as defined in Claim 1 or Claim 2 wherein each of the first and second parts of the toggle mechanism has a pivot arm.
4. The clamp as defined in Claim 3 wherein one pivot arm is an actionable pivot arm which is operable by the handle and the other pivot arm is a biased pivot arm which is biased by a biasing member.
5. The clamp as defined in Claim 4 wherein the biased pivot arm has a stop surface for engaging the part of the toggle mechanism having the actionable pivot arm so as to limit the action of the biasing member.
6. The clamp as defined in Claim 4 or Claim 5 wherein the actionable pivot arm has a stop surface for engaging the part of the toggle mechanism having the biased pivot arm so as to prevent the toggle mechanism going into an over-centre position.
7. The clamp as defined in any one of claims 4 to 6 wherein the actionable and biased pivot arms each have an alignment surface which surfaces engage each other in the first position of the toggle mechanism.
8. The clamp as defined in Claim 7 wherein the pivot arm has a pivot which is formed between the alignment and stop surfaces of the pivot arm, preferably the pivot is formed to have an angle of from 75° to 900.
9. The clamp as defined in any one of claims 4 to 8 wherein the actionable arm as an urging surface for the handle to engage.
10. The clamp as defined in any one of the preceding claims wherein the second part of the toggle mechanism has a formation for engaging with a corresponding formation on the clamp housing for limiting the movement of the second part in the clamp housing.
11. A clamp substantially as illustrated in or as described in relation to the Figures of the accompanying drawings.
12. A kit comprising a clamp as defined in any one of the preceding claims and one or more elongate elements.