1. Field of the Invention
The present invention relates to an extrusion-type liquid delivery apparatus to deliver a liquid contained beforehand in a container with a plunger, such as an extrusion-type liquid delivery apparatus for medical use.
2. Description of the Related Art
Typically, the extrusion-type liquid delivery apparatus, which pushes a liquid contained in a container out with a plunger along the inner wall of the container, employs the technique of pushing the collar provided at one end of the plunger to move the plunger and thereby to push out a liquid contained in the container. In this case, a liquid delivery portion is provided on the side opposite to the side where the plunger is inserted in the liquid-filled container, and the liquid delivery portion has a small hole for delivering the liquid. In many cases, a tube composing a liquid delivery channel is connected to this liquid delivery portion, through which the liquid can be delivered to a desired place by a push motion of the plunger. If precise control of liquid delivery is not required, the plunger may be pushed manually. However, when liquid delivery is performed at a constant rate over a long period of time, the extrusion-type liquid delivery apparatus is used.
The conventional extrusion-type liquid delivery apparatus has a gripping device to grip the collar provided at one end of the plunger.
With the conventional extrusion-type liquid delivery apparatus, however, gripping of the collar of the plunger is done manually by the operator. Because of this, it is difficult for one operator to load a drug-filled container on a plurality of extrusion-type liquid delivery apparatuses one by one and to start a liquid delivery, especially in emergencies.
An object of the present invention is to provide an extrusion-type liquid delivery apparatus capable of automatically gripping the collar of the plunger.
The extrusion-type liquid delivery apparatus provided by the present invention comprises: a plunger mover to move a plunger; a plunger mover driver to move the plunger mover; a pair of hooks rotatably mounted on the plunger mover with the bent ends projecting from the plunger mover, and having slopes at the bent ends; a spring to close the bent ends of the pair of hooks by spring force; and a clamp to block a liquid delivery channel connected to a container.
In this extrusion-type liquid delivery apparatus, it is possible to automatically rotate the bent hooks to grip the collar of the plunger with the hooks simply by moving the plunger mover, and therefore the operator can load, with a plurality of delivery apparatuses, a liquid-filled container that contains a liquid and grip the plunger in a short period of time. Moreover, since an additional special actuator for automatic gripping is not required, this apparatus can be of simpler construction and can be manufactured at lower cost.
Referring to
At the other end of the guide rod 16, the plunger mover 26 to move a plunger 54 (described later) is mounted. The plunger mover 26 is provided with a pair of hooks 28a and 28b which are rotatable around a fulcrum 30. The bent ends of the hooks 28a and 28b protrude from the plunger mover 26 and have slopes. The slope formed at the bent end of the hook 28a and that of the hook 28b face to each other. The slopes of the hooks 28a and 28b are outwardly sloped in the direction of pushing the plunger 54 (i.e., to the left in
The plunger mover 26 is provided with a release button 34, and the release button 34 has slopes that contact the opposite ends of the bent ends of the hooks 28a and 28b. The release button 34 makes up a manual release means to rotate the hooks 28a and 28b against the spring force of the push spring 32. Within the carriage 18, a clutch mechanism capable of disengaging the nut from the lead screw 12 is provided. Pushing the release button 34 will actuate the clutch mechanism to disengage the nut within the carriage 18 from the lead screw 12.
The plunger mover 26 is provided with a plunger grip sensor 36, which has a sensor arm 38. A plunger grip sensor chip 40 is supported by the plunger mover 26. These components including the plunger grip sensor 36 make up a plunger grip detecting means to detect whether or not the plunger 54 is gripped.
A groove 42 is formed on the top of the frame 2, and also a clamp 44 is mounted on the top of the frame 2. The clamp 44 contains pin drivers 58a and 58b, which expand and contract direct-driven pins 60a and 60b.
A flange 48 is provided at one end of a container 46 in which a liquid is contained. At the other end of the container 46, a liquid delivery portion 50 is provided, to which a liquid delivery channel 52 is connected. Further, the plunger 54 is inserted into the container 46, and the plunger 54 has a gasket 78 at one end that is close contact with the inner wall of the container 46. At the other end of the plunger 54, a collar 56 is provided.
Now, referring to
In this extrusion-type liquid delivery apparatus, when the operator engages the flange 48 into the groove 42, loads the container 46 on the top of the frame 2, and then enters a liquid delivery start command from the operation/display panel 64, the microprocessor 62 issues a clamp command to the clamp drive circuits 74a and 74b, the pin drivers 58a and 58b expand the direct-driven pins 60a and 60b respectively as shown in
Thereafter, the microprocessor 62 issues a rotation command to the motor drive circuit 70 to rotate the drive motor 6, which moves the carriage 18 and thereby moves the plunger mover 26 in the direction of arrow M in
Meanwhile, the microprocessor 62 monitors a grip sensor signal to be input from the plunger grip sensor 36 via the sensor signal processing circuit 68, in order to determine whether the plunger 54 is gripped. Specifically, when the plunger mover 26 is moved in the direction of arrow M from the state in
Then, the microprocessor 62 issues a rotation command to the motor drive circuit 70 to rotate the drive motor 6 and thereby to move the carriage 18, resulting in the plunger 26 moving, in the direction opposite to the direction of arrow M in
After the plunger 54 is automatically gripped in this way, the microprocessor 62 issues a clamp release command to the clamp drive circuits 74a and 74b to cause the pin drivers 58a and 58b to contract the direct-driven pins 60a and 60b respectively as shown in
After the liquid delivery is completed, the operator manually pushes the release button 34 in the direction of arrow P as shown in
In such extrusion-type liquid delivery apparatus, the hooks 28a and 28b automatically rotate to grip the collar 56, simply by moving the plunger mover 26 and the gripper 76, and therefore the operator can perform the mounting of the container 46 containing a liquid and the gripping the plunger 54 with a plurality of liquid delivery apparatuses in a short period of time. Also, since there is no need to add a special actuator for automatic gripping, the structure is simple and manufacturing cost can be reduced. Moreover, moving the plunger mover 26 in the direction opposite to arrow P, with the release button 34 pushed in the arrow P direction, will release the collar 56 from the hooks 28a and 28b, and also allows the plunger mover 26 to move to the point where a liquid delivery starts. This makes it possible to remove an emptied container 46 and to pull the plunger mover 26 back to the prescribed position manually, and therefore the container 46 can be replaced quickly. Furthermore, since the output of the plunger grip sensor 36 is monitored by the microprocessor 62, it is possible to detect whether or not the gripper 76 has gripped the collar 56, namely the plunger 54, and therefore the plunger 54 can be gripped reliably by the gripper 76. Also, the plunger mover 26 is moved in the direction opposite to the direction of pushing the plunger 54 after the collar 56, namely the plunger 54, has been gripped by the gripper 76, and therefore, even if the inner pressure of the container 46 rises when the gripper grips the collar 56, the inner pressure of the container 46 can be lowered. This prevents the liquid from being delivered at a burst when the direct-driven pins 60a and 60b unblocked the liquid delivery channel 52.
For the drive motor 6, a stepping motor or DC motor can be employed. For the position detecting means to detect the position of the carriage 18, a magnetic position detector can be used. Also, an optical or magnetic rotary encoder can be provided at the end of the lead screw 12, as a position detecting means to detect the position of the carriage 18. Alternatively, a plunger mover driver having a linear motor can be used for this purpose. Although the plunger grip sensor 36 is used as a plunger grip detecting means in the above embodiment, a magnetic proximity switch or a load sensor that faces and contacts the collar 56 can be used as a plunger grip detecting means. Also, other springs can be used instead of the push spring 32 used in the above embodiment, to close the bent ends of the hooks 28a and 28b by spring force.
The extrusion-type liquid delivery apparatus according to the present invention can be used for applications that require automatic gripping of a plunger which is enabled with a simple construction, such as a medical syringe pump to deliver a liquid contained beforehand with a plunger.
Number | Date | Country | Kind |
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2004-110047 | Apr 2004 | JP | national |
2004-317991 | Nov 2004 | JP | national |