Machine element or mechanism – Mechanical movements – Reciprocating or oscillating to or from alternating rotary
Reexamination Certificate
2001-02-16
2003-09-16
Joyce, William C (Department: 3682)
Machine element or mechanism
Mechanical movements
Reciprocating or oscillating to or from alternating rotary
C184S005000
Reexamination Certificate
active
06619148
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lubricant supply device for supplying lubricant to a screw shaft of a rolling-member screw apparatus and to a rolling member screw apparatus using such a lubricant supply device.
2. Description of the Related Art
A rolling-member screw apparatus such as a ball screw has conventionally been known. The rolling-member screw apparatus comprises a screw shaft, a nut member and a plurality of balls. The screw shaft has a ball running groove formed spirally on the outer periphery of the screw shaft. The nut member is engaged with the screw shaft. The nut member has a ball circulation passage formed therein, which includes a loaded ball running groove formed spirally on the inner periphery of the nut member so as to correspond to the above-mentioned ball running groove. The balls are placed and received in the ball circulation passage. A relative rotation of the nut member to the screw shaft causes the balls to roll in the ball running groove so that the nut member can move linearly relative to the screw shaft.
With respect to a lubricant supply device for lubricating the ball running groove of such a rolling member screw apparatus, the present inventor made an invention of a lubricant supply device as shown in
FIG. 10
(as disclosed in Japanese Patent Application No. H11-50922). The lubricant supply device comprises an application member
52
having tongue portions
51
,
51
coming into contact with ball running grooves of a screw shaft to apply the lubricant on the ball running groove, a casing
54
for forming a lubricant storage member
53
, from which the lubricant is supplied to the application member
52
, and a joint member
55
for controlling an amount of lubricant supplied from the lubricant storage member
53
to the application member
52
. An occlusion member
56
, which absorbs the lubricant to store it, is fitted into the lubricant storage member
53
.
When the tongue portions
51
,
51
move, while coming into contact with the ball running grooves, the lubricant is supplied from the tongue portions
51
,
51
into the ball running grooves. When an amount of the lubricant absorbed in the application member
52
is gradually decreased, the lubricant absorbed in the occlusion member
56
is supplied to the application member
52
through the joint member by capillary action. Accordingly, a prescribed amount of lubricant is always absorbed in the application member, thus making it possible to stably supply the lubricant from the tongue portions
51
,
51
to the ball running grooves.
In the lubricant supply device disclosed in the above-mentioned Japanese Patent Application No. H11-50922, the single application member
52
has the tongue portions
51
,
51
, which are arranged in line in the axial direction of the screw shaft. The number of the tongue portions
51
,
51
is equal to the number of the thread grooves of the screw shaft. The lubricant is supplied to the entire ball running grooves, irrespective of the number of the thread grooves of the screw shaft. Arrangement of the application member
52
below the lower portion of the lubricant storage member causes the lubricant to concentrate in the application member
52
by the function of gravity, thus gathering the lubricant in the single place to apply it onto the ball running grooves.
However, when the tongue portions
51
,
51
, the number of which is equal to the number of the thread grooves, are arranged in line on the single application member
52
, the length of the application member
52
increases in proportion to the number of the thread grooves of the screw shaft, with the result that the length of the lubricant supply device in its longitudinal direction may become unnecessarily longer.
In addition, a user does not always mount the lubricant supply device on the ball screw so that the application member
52
of the lubricant supply device is placed on the lower side of the ball screw. When the application member
52
is not placed on the lower side of the ball screw, the lubricant received in the lubricant storage member
53
may not be supplied to the application member
52
.
SUMMARY OF THE INVENTION
An object of the present invention is therefore to provide a lubricant supply device, which permits supply of substantially all the amount of lubricant received in the device to flow out and which has a decreased length of the device in the axial direction of the screw shaft, and a rolling member screw apparatus.
In order to attain the aforementioned object, a lubricant storage member is divided into a plurality of compartments arranged in the circumferential direction of the screw shaft. The number of the compartments is equal to or larger than the number of the thread grooves of the screw shaft. Application members are placed in correspondence to the compartments. Each of the application members has a tongue portion. More specifically, the lubricant supply device of the present invention, which is to be fitted to a nut member engaging with a screw shaft having at least two thread grooves through rolling members to supply lubricant to the screw shaft along with a relative rotational motion of the nut member to the screw shaft, comprises:
a plurality of application members for applying the lubricant on the screw shaft, each of said application members having a tongue portion, which comes into contact with rolling-member running surfaces of the screw shaft;
a casing for forming a lubricant storage member, from which the lubricant is supplied to said application members; and
a plurality of control members for controlling an amount of the lubricant supplied from said lubricant storage member to said application members,
wherein:
said lubricant storage member is formed into a cylindrical shape into which the screw shaft is loosely inserted, said lubricant storage member being divided into a plurality of compartments arranged in a circumferential direction of the lubricant storage member, the number of the compartments being equal to or larger than the number of said at least two thread grooves of the screw shaft;
said application members are placed in correspondence with the compartments; and
each of said application members has a tongue portion.
According to the present invention having the above-mentioned structure, the relative rotation of the screw shaft to the nut member causes the lubricant to be supplied from the tongue portions of the application members to the rolling member running surfaces of the screw shaft. The control members control an amount of lubricant supplied from the lubricant storage member to the application members. As a result, an amount of lubricant supplied from the lubricant storage member to the application members does not vary drastically in the course of time, thus leading to a constant supply of the lubricant in a prescribed amount from the application members to the screw shaft. It is therefore possible to apply the lubricant to the screw shaft in a minimum amount for a long period of time.
The relative rotation of the tongue portions to the screw shaft causes the tongue portions to move along the spiral rolling member running surfaces, while applying the lubricant onto the rolling member running surfaces of the screw shaft. The lubricant storage member is divided into a plurality of compartments arranged in the circumferential direction of the lubricant storage member. The number of the compartments is equal to or larger than the number of the thread grooves of the screw shaft. The application members are placed in correspondence to the compartments. Accordingly, the rolling member running surfaces can be lubricated entirely. In addition, almost all the amount of lubricant received in the lubricant supply device can be supplied to flow out, irrespective of the mounting posture of the lubricant supply device on an rolling member screw apparatus. Further, each of the application members has the single tongue portion formed thereon. It is therefore possible to prevent the application memb
Armstrong Westerman & Hattori, LLP
Joyce William C
THK Co. Ltd.
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