JPH0221641Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive mechanism that allows two types of driven members to be driven by one motor without interfering with each other in operating time.

As a clutch that is installed on a rotating shaft and transmits the rotation of the rotating shaft to a driven member, a one-way clutch is commercially available that transmits rotation of the rotating shaft in only one direction to the driven member and does not transmit rotation in the other direction. There is. Recently, at least one set of such one-way clutches is installed on a camshaft that is substantially integrated with the shaft of a motor, with the directions of transmission being opposite to each other, and a driven member is mounted on the one-way clutch. A drive mechanism has been proposed in which a fixed motor is rotated in the forward and reverse directions so that two types of driven members can be driven without interfering with each other in operating time. −81135).

However, in such a drive mechanism, if the shaft is rotated in the normal direction by the motor, and the driven member of one one-way clutch is rotated in the normal direction,
During this time, the driven member of the other one-way clutch should be stopped without rotating, but there is a positive load (i.e., a load acting in the opposite direction to the direction in which one driven member is intended to rotate). ), or when the shaft rotates in reverse or forward direction, if the load is small, the one-way clutch part that transmits rotation to the other driven member often rotates in the forward direction, albeit slightly, and as a result, the other driven member rotates in the forward direction. The driven member rotates slightly in the normal direction (slight movement). For example, when such a drive mechanism is applied to an automatic chemical analyzer, the driven member becomes an independent dual pump, but if the above-mentioned micro-movement occurs, the flow rate may be incorrect, the fluid may not be properly stopped, etc. This results in a decrease in the analytical accuracy of the device.
Therefore, conventionally, a notch is provided in a part of the outer periphery of the other driven member to prevent forward rotation, so that when the driven member rotates in the normal direction, it catches a claw provided on the outside. A notch is provided on a part of the outer periphery of the driven member so that when the member is reversed, it is caught by a claw provided on the outside to prevent the driven member from reversing. However, with such a configuration, the rotation will be forward or reverse until the pawl is caught in the notch, and even if multiple notches or pawls are provided, a certain degree of slight movement will be inevitable, and the configuration will be complicated. become

The present invention aims to solve such problems.

The present invention provides at least one set of one-way clutches installed on a camshaft that is substantially integrated with the shaft of the motor so that the transmission directions are opposite to each other, and a driven member is fixed on each of the clutches, respectively. By rotating one motor forward and reverse,
In a drive mechanism configured to be able to drive two types of driven members without interfering with each other during operating time, an elastic body is provided on the shaft between the pair of one-way clutches, and the pressing force of the elastic body causes each of the two types of driven members to be driven. The driven member of the clutch is directly or indirectly pressed against the fixed member, and the axial force between the two driven members is transmitted on the shaft between the two clutches, but the force in the rotational direction is not transmitted. It is characterized by the provision of bearings.

1 and 2 are a front view and a side view of a pump drive mechanism shown as an embodiment of the present invention.
For convenience, a case will be described in which there is one pump for each pump (two in total) whose operating times do not interfere with each other, and these pumps are driven by one motor. In the figure, 1 is a cam shaft, and this shaft is integrated with the shaft of a motor 2. One-way clutches 3A and 3B are fitted onto the shaft at an appropriate distance so that their transmission directions are opposite to each other.
Eccentric cams 4A and 4B are fixed on each of the clutches, and connecting arms 6A and 6B are provided around each eccentric cam via ball bearings 5A and 5B, respectively. Plungers 7A and 7B which directly reciprocate by the movement of an eccentric cam that converts the rotational movement of the motor 2 into reciprocating movement are tiltably connected to each of the connecting arms. The plungers 7A, 7
B constitutes the main part of the liquid suction/outflow of the pumps 8A and 8B. As shown by the solid line, when the plunger 7A moves to the right, liquid is sucked from the liquid tank 9, and as shown by the broken line, the plunger 7A moves to the right. When 7B moves to the left,
Liquid is drained to the outside. 10A, 10B, 10
C and 10D are balls that float or sink in the liquid path to flow or stop the liquid according to the movement of the plunger. In the figure, 11A, 11B, 1
1C is a collar made of a material that has a small coefficient of friction with the shaft, and whose inner diameter is slightly larger than the outer diameter of the shaft 1. Therefore, these collars can move in the axial direction of the shaft and can rotate relative to the shaft with little friction with the shaft. These collars are used to transmit axial forces and to position other members in the proper axial position. A spring 12 for applying a pressing force in the axial direction is provided around the shaft between the collar 11B and the one-way clutch portion 3A. Spring 12 is also shaft 1
It is arranged so that there is almost no friction between the Further, a thrust bearing 13 is provided between the spring 12, the one-way clutch 3A, and the eccentric cam 4A. This bearing 13 is used to transmit axial force between the spring 12 and the eccentric cam 4B side, but not to transmit rotational force. 14A and 14B are fixed supports. Since the spring 12 applies a pressing force in the axial direction of the shaft, the eccentric cam 4B, together with the one-way clutch 3B, is pressed against the support 14A via the collar 11A. Similarly, the eccentric cam 4A is connected to the collar 11 together with the one-way clutch 3A.
C is pressed against the support body 14B.
Since this pressing force is relatively strong, color 1
1A and 11C generate a frictional force against the rotational force between them and the supporting members 14A and 14B, respectively. Furthermore, since the eccentric cams 4A, 4B are pressed against the collars 11C, 11A, respectively, a frictional force is generated which resists the rotation of the eccentric cams 4A, 4B. This cam 4A, 4
The resistance force (frictional force) against rotation of B is selected to be considerably smaller than the rotational force transmitted by the one-way clutch and sufficient to maintain the stoppage of the eccentric cam to which the rotational force is not transmitted by the one-way clutch. It is.

In such a drive mechanism, when the shaft 1 of the cam 1 is rotated in the normal direction (clockwise) by the motor 2,
The eccentric cam 4A rotates normally against the resistance force. At this time, the collar 11c is attached to the eccentric cam 4A (clutch 3
A) to generate a frictional force between the eccentric cam 4A
It also rotates to some extent. On the other hand, the rotational force from the eccentric cam 4A is not transmitted to the spring 12 or collar 11B side because of the bearing 13. in the end,
No rotational force exceeding the above-mentioned resistance force (frictional force) is applied to the eccentric cam 4B, and the cam 4B
The state in which it is pressed against the support body 14 via A is maintained. In this case, colors 11A, 11B,
The spring 12 also maintains the stopped state like the cam 4B.

Also, when the shaft 1 is reversely rotated by the motor 2, the cam 4B, collar 11A, collar 11B, and spring 12 rotate, but the cam 4 rotates as in the case of forward rotation.
A and collar 11C maintain a stopped state.

Incidentally, instead of installing the spring 12 and the bearing 13 on the shaft between the collar 11B and the one-way clutch 3A,
It may be provided around the shaft between B.

In addition, in the above embodiment, in order to set the position of the cam etc., a collar was interposed between the cam and the support, and the cam was indirectly pressed against the support through the collar. Instead, for example, the cam 4B may be directly pressed against the support body 14A.

According to the invention, at least one pair of one-way clutches are installed in opposite directions on a camshaft substantially integrated with the shaft of the motor, and a driven member is fixed on the clutches, and one In a drive mechanism that can drive two types of driven members whose operating times do not interfere with each other by rotating the motor forward and reverse, the driven member that should be in a stopped state has a very simple and inexpensive configuration. It is possible to prevent micro-tremors.

[Brief explanation of drawings]

1 and 2 are a front view and a side view, respectively, of a pump drive mechanism shown as an embodiment of the present invention. 1: Camshaft, 2: Motor, 3A, 3B:
One-way clutch, 4A, 4B: Eccentric cam, 5
A, 5B: ball bearing, 6A, 6B: connecting arm, 7A, 7B: plunger, 8A, 8B: pump, 11A, 11B, 11C: collar, 12: spring, 13: bearing, 14A, 14B: support.

Claims (1)

[Scope of utility model registration request] At least one set of one-way clutches is installed on a camshaft that is substantially integrated with the shaft of the motor so that the transmission directions are opposite to each other, and a driven member is respectively fixed on each of the clutches. In the drive mechanism, an elastic body is provided on the shaft between the pair of one-way clutches in a drive mechanism that can drive two types of driven members without interfering with each other during operating time by rotating the clutch in the forward and reverse directions. , each driven member is directly or indirectly pressed against the fixed member by the pressing force of the elastic body, and the axial force between both driven members is transmitted onto the shaft between both clutches, but the force in the rotational direction is A drive mechanism for a driven member that is equipped with a bearing to prevent force from being transmitted.