US2575640A - Lubricating system for air motors - Google Patents

Description

Nov. 20, 1951 E. H. SHA1-'F 2,575,640

LUBRICATING SYSTEM FOR AIR MOTORS Filed Nov. a, 1947 I vue est CHL Sh o.

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Patented Nov.y20, 1951 LUBRICATING SYSTEM FOR AIR MOTORS Ernest H. Shaft, Spring Lake,`Mich., assignor to Keller Tool Company, Grand Haven, Mich., a

corporation of Michigan Application November 8, 1ML-Serial No. 784,873

The present invention `pertains to pneumatic tools and more particularly to tools embodying .rotary vane type air motors.

.An important object of Vthe invention is to .provide for effective lubrication of the various working parts of a tool of the above character through the utilization of air under pressure delivered to a lubricant Areservoir when the tool is in opera tion Aand serving to force lubricant from the reservoir to the Ytool parts upon interruption of the air supply.

.A further object is to provide such a tool which is extremely compact, highly efficient in operation and inexpensive to manufacture.

Other objects and advantages of the invention will become apparent from the following detailed description of the preferred embodiment illustrated in the accompanying drawings in which:

Figure 1 is a perspective view of A a portable grinder constructed in accordance with the present invention.

Fig. 2 is a central longitudinal section of the tool shown in Fig. 1 taken inthe plane substantially perpendicular to the control valve therein.

Fig. 3 'is a transverse section taken substantially in the plane of line 3-3 in Fig. 2.

While the invention is susceptible of various modifications and alternative constructions, there is shown in the drawings and will herein be de- Y the spirit and scope of the invention as expressed l in the appended claims.

As illustrated in the drawings, the exemplary form of the invention is shown embodied in a portable pneumatic grinder which includes a gen erally cylindrical casing I2 having therein a motor chamber It within which is an air motor i6 for actuating the tool. The motor I3 is of the vane type `and comprises a cylinder i8 having an eccentrically disposed bore I3 therein, and a rotor 24 eccentrically disposed within the bore I9, and ends of the cylinder being closed by end plates 28 and 22. The rotor 24 is provided with equally spaced slidable vanes for cooperation with the wall of the bore I 9 and is mounted on a central spindle 26 extending through the end plates 2G and 22' and supported in bearings 28 and 29.

As shown, the spindle 26 is enlarged intermediate its ends to provide a shoulder 3i! against which the lower bearing 29 is held by means of a nut 3| screw-threaded on the spindle. The

s claims. (c1. 121-34) vouter race of the bearing 29 is received vin a recess `provided therefor in a retaining ring 32 screw-#threaded iin the forward end of the casing I2 and holding the race against the motor end plate 22. To receive the upper bearing 28 the -rear -end plate 20 is of cup shape. Thus ithas .a rearwardly projecting ange 2| formingxA a, recess into which A'the outer race of the bearing is fitted. The bearing is clamped between `the [casing I2 Vand the 'end plate '20 by the `revtaining ring 32 acting through the forward end plate 22 and the cylinder I8.

The spindle`26 extends through 'the ring 32, beyond the casing I2, and adjacent the outer end thereof, it is fashioned into a split sleeve 33 having a tapered en'd portion '34, which tof'- gether with a nut 35 forms fa collet-"chuck for the reception of a tool'3I.` A l Pressure `fluid, such as compressed air, to actuate the motor'IG is supplied to the tool from AVany suitable source (not shown) by way of e.

ffitting 31 received in a bore 38 `in the rearY end -of `the casing |2. From thefbore 38 air passes through a longitudinal passage 39 to ajcontrol valve 40. The valve 40 includes a bushingl'l closely fitted in a transverse bore 42 vin the casing I2. is a spring 'biased valve plunger 43 having a portion 43a, which is adapted to seat against the inner end of the bushing 4|. One end of the plunger Y43 extends 4beyond the :casing I2 (Fig. l) for 'engagement by a lever 44 positioned for actuation by the vfinger of an operator.

From the valve 40, air passes through a port 45 in the l'bushing '4| into a transverse passage 46 and by way of apassage 41 into an annular inlet distribution channel or passage '48 formed by a rabbet groove in the iiange 2| of the rear end plate 20 in cooperation with the outer race of the bearing 28 and the casing I2. From the inlet channel 48 air is delivered Ato the motor cylinder I4 through aport 49 inthe end platen.

Spent air is exhausted from the motor it through slots 50 in the wall of the cylinder I8 'into an exhaust chamber 5| defined by the outer suriace of the cylinder coacting with the inner wall of the motor chamber lli, and through exhaust ports V52 in the casing I2 to the atmosphere.

To lubricate the tool I provide means including Ya lubricant reservoir and a system of interconnecting passages to which air under pressure is supplied when the tool is running and which is operative upon stopping the tool to supply lubricant thereto. More specifically, I provide a lubricant reservoir in the casing I'2 with con- Shiftable axially within the *bushing 4l necting passages through which air under pressure is supplied when the valve 4D is opened, and upon interruption of the air supply, incident to the closure of the valve 46, lubricant, such as light oil, is forced from the reservoir to the rotor chamber I9 and to chambers adjacent the bearings 28 and 29. Additionally, I provide a metering device or restriction to prevent 'escape of lubricant from the reservoir upon equalization of pressure on opposite sides of the restriction.

As shown, adjacent the rear bearing 28 the bottom of the casing l2 is counterbored, and toging passages 56 therein. :'In the present instance, the lubricant reservoir :is in the form of a generally rectangular chamber 60 adjacent the rear end of the casing I2 which is closed by means of a plug 6l closely fitted in a bore 62 in the wall of the casing l2. The

plug 6l has a filling opening therethrough which is adapted to be closed by a screw and washer 63 and 64, respectively.

" Air under pressure is supplied to the reservoir `6l) when the valve 48 is opened to admit air to actuatev the motor by means of a passage 65 extending therefrom longitudinally of the casing |2 and having one end opening into the annular inlet channel 4R. Intermediate its ends. the passage 65 is intersected by the transverse passage 46. As previously set forth; the inner end of the latter serves as an air inlet passage; however, it is interrupted by the valve bushing 4|, and thus admission of air under pressure to the lubricant reservoir 60 is solely by way of the inlet channel 48.

In the present instance, restriction of communication between the lubricant reservoir 60 and the motor I6 is accomplished by a cylindrical plug 66 positioned within and adjacent the outer end of the passage 46. The plug 66 is retained in the passage by means of a second plug 61 closelv fitted in the end of the passage 46 and having its outer end peened into engagement with the wall of the casing I2` The plug 66 is of slightly smaller diameter than that of the passage 46 thus providing a space between the two. It has been found that an effective difference of these two diameters is on the order of .001 of an inch. Thus air under pressure can enter the reservoir 60 from the inlet channel 48 by way of the passage 65 around the plug 66. and a. small quantity lubricant will be forced out of the reservoir reversely along the same route until the v.pressure on both sides of the plug is equalized. Upon such equalization of the pressure, the plug 66 provides sufficient restriction to prevent leakage. While in the illustrative embodiment the plug 66 is shown to be of a diameter to provide aspace between it and the wall of the passage 46, va. porous plug such as one of sintered metal fitted in the passage 46 can be used instead.

Lubricant delivered to the inlet channel 48 is conducted into the motor cylinder I8 to lubricate the wall of the bore i9 and the rotor 24 and its'ylvancs.v n f,

Lubricant is supplied to the bearing chamber 53 by means of a passage 68 extending therefrom and connecting with the passage 46 adjacent the plug 66. Thus, when air supply is interrupted incident to the closing of the valve 40, lubricant will be delivered to the chamber 53 as well as to the channel 48.

summarizing, air under pressure is delivered to the tool by way of the valve 46, port 45, passages 46 and 4l to t-he inlet channel 48 and thence into the cylinder I6 through port 49 to drive the motor. Also from the channel 48 air under pressure is delivered to the lubricant reservoir 60 through the passage 65 around the plug 66 in the passage 46. When the valve 4l) is closed, interrupting the supply of pressure air, some lubricant is forced from the reservoir 6! until the pressure on both sides of the plug 66 is equalized, such lubricant being conducted to the channel 48 by way of the passage 65 and to the chamber 53 where it lubricates the bearing 28 by way/cf the passage. 68. From the channel 43 lubricant is delivered into the cylinder through the port 49, and from' the chamber 63 lubricant is deliveredto the chamber 54 through the passages 55 and 56 to lubricate the bearing 29.

From the foregoing, it can be seen that I have provided a highly eicient and extremely compact tool having relatively few parts with a consequent saving in manufacturing costs. Further, effective lubrication of the tool is provided through the provision of a closed lubricant reservoir to which air under pressure is supplied when the tool is in operation and which has communication with lubricant chambers provided for each of the spindle bearings and the rotor chainber, lubricant being delivered from the reservoir to the chambers as an incident to the interruption of the air supply to the tool, provision being made to prevent lubricant from escaping from the chamber upon equalization of pressure therein with that outside.

I claim as my invention:

1. A rotary pneumatic tool comprising, in combination, an elongated casing having a chamber in one end and a closed lubricant reservoir at the other end, a motor in said chamber comprising a cylinder and end plates at the forward and rear ends thereof, said cylinder coacting with the inner wall of the motor chamber to form an exhaust chamber, a spindle extending through the cylinder end plates axially thereof, a rotor mounted on said spindle and eccentrically dis.- posed within said cylinder and having varies slid.- ably engaging the inner cylinder wall, a bearing for the rear end of the spindle comprising an outer race carried by the rear end plate and an inner race on the spindle, a bearing for the forward end of the spindle comprising an outer race mounted in the casing and an inner race fast on the spindle, and means for supplying air under pressure to the motor chamber. and lubricant reservoir comprising a'yalve controlled air passage and an annular inlet channel, the outer race of the rear bearing coasting with the end plate and with said casing to form said channel, inlet ports connecting said channel to said motor and a restricted passage connecting said channel to said reservoir, a rear lubricant chamber formed by said casing and the rear spindle bearing and in restricted communication with said lubricant reservoir and a second lubricant chamber formed by the forward end plate and ,75 bearing, said spindle having a duct connecting said bearing chambers so that lubricant is conducted from said reservoir to said motor and bearing chambers by reason of pressure built up in the reservoir under operating conditions.

2. A rotary pneumatic tool comprising, in combination, an elongated casing having a chamber in one end and a closed lubricant reservoir at the other end, a motor in said chamber including a spindle, a rotor mounted on the spindle and a bearing rotatably supporting said spindle, and means for supplying air under pressure to the motor chamber and lubricant reservoir, said means including a valve-controlled air passage and an annular inlet channel, longitudinally disposed inlet ports connecting said channel with said motor chamber and providing restricted communication with said reservoir, and a lubricant chamber for said bearing in concentric relation with said channel and also in restricted communication with said reservoir whereby lubricant is conducted from said reservoir to said motor and bearing chambers by reason of pressure built up in the reservoir under operating conditions.

3. A rotary pneumatic tool comprising, in combination, a elongated casing having a chamber in one end and a closed lubricant reservoir at the other end, a motor in said chamber including a spindle, a rotor mounted on the spindle and a bearing rotatably supporting said spindle,

and means for supplying air under pressure to the motor chamber and lubricant reservoir, said means including a valve-controlled air supply passage and a distribution passage communieating with said air supply passage and in restricted communication with said reservoir, and a lubricant chamber for said bearing also having restricted communication with said reservoir whereby lubricant is conducted from said reservoir to said motor and bearing chambers by reason of pressure built up in the reservoir under operating conditions.

ERNEST H. SHAFF.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 967,693 Weinland Aug. 16, 1910 994,400 Holt June 6, 1911 1,809,141 Mock June 9, 1931 1,878,747 Youngblood Sept. 20, 1932 1,947,430 De Mooy Feb. 13, 1934 1,956,644 Hamerly May 1, 1934 2,099,280 Shaff Nov. 16, 1937 2,111,583 De Mooy Mar. 22, 1938 2,238,101 Cliiord Apr. 15, 1941 2,384,872 Baker et al Sept. 18, 1945 2,407,613 Mannet al Sept. 10, 1946

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