JP4669729B2 - Variable capacity swash plate type hydraulic rotating machine - Google Patents

Description

  The present invention relates to a variable capacity swash plate type hydraulic rotating machine mounted on a construction machine such as a wheel loader.

  There exists a thing shown by patent document 1 as this type of prior art. FIG. 4 is a cross-sectional view showing a conventional variable displacement swash plate type hydraulic rotating machine disclosed in Patent Document 1, that is, a variable displacement swash plate hydraulic pump.

  In this prior art, a rotary shaft 43, a cylinder block 22, a plurality of pistons 21, a plurality of shoes (not shown) and the like are provided in a pump casing 26, and a variable capacity portion, that is, a displacement, is provided between the pump casing 26 and each shoe. A swash plate 23 that determines the volume is provided to be tiltable.

  In this variable displacement hydraulic pump, the rotary shaft 43 is rotationally driven by a prime mover or the like of a wheel loader, whereby the cylinder block 22 rotates integrally therewith, and each piston 21 in each cylinder of the cylinder block 22 is rotated. The reciprocating motion is performed, and hydraulic oil sucked into each cylinder from a tank or the like according to the reciprocating motion of these pistons 21 is discharged as high-pressure oil.

  Further, on the outer side of the cylinder block 22 in the radial direction, there are a servo piston storage portion 35, a servo piston 27 stored in the servo piston storage portion 35, and a slider stored in a slider storage portion formed in the servo piston 27. 39 is provided, and a pin 36 provided on the swash plate 23 is connected to the servo piston 27 via a slider 39.

When the tilt control pressure acts on the pressure receiving surfaces 31 and 32 of the servo piston 27, springs 29 and 30 are provided inside the sliding portions 31A and 32A of the servo piston 27 and bias the servo piston 27 to the neutral position. The servo piston 27 slides and displaces against this force. As a result, the swash plate 23 tilts in the direction of arrow A or B in FIG. 3 via the slider 39 and the pin 36.
US Patent Application Publication No. 2002 / 0014149A1

  By the way, in the above-described prior art, the springs 29 and 30 for urging the servo piston 27 to the neutral position are provided inside the sliding portions 31A and 32A configured as separate parts from the main body of the servo piston 27. After the springs 29 and 30 are assembled, the separate sliding parts 31A and 32A must be coupled to the main body by bolts 44 or the like. For this reason, a shaft misalignment occurs between the sliding portion 31A and the sliding portion 32A of the servo piston 27, the slidability of the servo piston 27 is deteriorated, and there is a concern that the reliability of the apparatus is lowered.

  Further, in order to integrally form the cylinder portion 38 in which each of the sliding portions 31 </ b> A and 32 </ b> A of the servo piston 27 is accommodated in the servo piston accommodation portion 35, the outer diameters of the springs 29 and 30 are set to the servo piston 27. It is necessary to make it smaller than the outer diameter of the sliding portions 31A and 32A. As a result, the spring force for returning the servo piston 27 to the neutral position tends to be weak. Further, if a strong spring force is to be obtained, the shape dimensions of the springs 29 and 30 and the servo piston 27 must be set large, and there is a problem that the entire apparatus becomes large.

  The present invention has been made from the actual state of the above-described prior art, and its purpose is to urge the servo piston without causing a fear of shaft misalignment in the sliding portion of the servo piston and causing an increase in the size of the apparatus. An object of the present invention is to provide a variable capacity swash plate type hydraulic rotating machine capable of setting a spring force strongly.

In order to achieve the above object, the present invention provides a servo piston that tilts a swash plate that determines a displacement volume, a servo piston storage part that stores the servo piston, and a spring that biases the servo piston to a neutral position. In the variable displacement swash plate type hydraulic rotating machine provided with the above, the servo piston is composed of a single member including the sliding portion, and the spring is provided at each of the axially outer positions of both end faces of the sliding portion, And a pair of spring seats arranged so as to sandwich these springs and receiving the force of the spring, and the inner diameter of the sliding surface of the cylinder portion of the servo piston storage portion, the inner diameter of each portion of the servo piston storage portion set the minimum diameter of the outer diameter of the sliding surface of the sliding portion of the servo piston, and sets the maximum diameter of the outer diameter of each portion of the servo piston, the servo piston The stroke amount to one side is s1, the stroke amount to the other is s2, and when the servo piston is in the neutral position, from the end surface of the sliding portion of the servo piston to the end surface of the cylinder portion of the servo piston housing portion L1 is the length on one side, L2 is the length on the other side, R1 is the shortest length on one side of the overlapping parts of the sliding surfaces of the cylinder part and the servo piston, and the shortest length is on the other side. When the length is R2,
L1> s1, R2> s1, L2> s2, R1> s2 in advance
It is characterized by the fact that it is set in the relationship .

  In the present invention configured as described above, the servo piston is composed of a single member including the sliding portion, so that there is no fear of an axial deviation in the sliding portion, and excellent slidability can be secured. In addition, since the springs that bias the servo pistons are arranged at the axially outer positions of both end faces of the sliding part of the servo piston, the outer diameter of these springs is restricted to the outer diameter of the sliding part of the sub piston. Can be set without being done. Therefore, the outer diameter of the spring can be set as large as possible, thereby increasing the force of the spring without increasing the size of the apparatus.

  Also, the inner diameter of the sliding surface of the cylinder part of the servo piston housing part is set to the smallest diameter among the inner diameters of each part of the servo piston housing part, and the outer diameter of the sliding surface of the sliding part of the servo piston is set to the servo Since the maximum diameter of the outer diameters of the respective parts of the piston is set, a single servo piston can be easily accommodated in the piston accommodating part.

  Further, the present invention is characterized in that, in the above invention, each of the springs is configured to bias the servo piston toward the neutral position.

  Further, the present invention is characterized in that, in the above invention, the spring comprises a compression spring.

Further, in the above invention, the inner diameter of the air gap of the servo piston housing portion in which the spring is provided, it is characterized by being larger than the inner diameter of the sliding surface of the cylinder portion.

According to the present invention, since the servo piston is composed of a single member, there is no fear of shaft misalignment in the sliding portion, and thereby excellent slidability can be secured, and the reliability of the apparatus can be improved as compared with the conventional one. In addition, since the spring that biases the servo piston is arranged at each of the axially outer positions of both end faces of the sliding portion of the servo piston, the force of the spring that biases the servo piston without increasing the size of the device. This contributes to the realization of downsizing of the apparatus.

  The best mode for carrying out the variable capacity swash plate type hydraulic rotating machine according to the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of an essential part showing a state in which a servo piston is neutral in a reference example of a variable capacity swash plate type hydraulic rotating machine previously devised by the present inventors , and FIG. 2 is a servo piston of the reference example shown in FIG. It is principal part sectional drawing which shows the state at the time of sliding.

The reference example is, for example, a variable displacement swash plate type hydraulic pump, and since the description is redundant, illustration is omitted. However, a pump casing equivalent to that shown in FIG. 3 described above, a cylinder block containing a piston, a swash plate, A pin provided on the swash plate and a slider which is engaged with the pin and accommodated in the slider accommodating portion of the servo piston are provided.

As shown in FIGS. 1 and 2, the reference example includes a servo piston housing 1 and a servo piston 2 having a slider housing 2H housed in the servo piston housing 1 and housing the slider (not shown). Cover plates 8 </ b> A and 8 </ b> B that close both ends of the servo piston housing 1 are provided. The slider storage portion 2H described above faces the opening hole 9 to the pump casing (not shown).

In particular, the servo piston 2 is composed of a single member including the sliding portion 2C, and the spring 3A is provided in each of the pressure chambers 6A and 6B positioned on the outer sides in the axial direction of both end faces 2A and 2B of the sliding portion 2C. , 3B are arranged. These springs 3A and 3B are composed of, for example, compression springs, and both of them are configured to bias the servo piston 2 toward the neutral position.

  The inner diameter of the sliding surface of the cylinder portion 1A of the servo piston housing portion 1 is set to the minimum diameter (the inner diameter of the dimension X) among the inner diameters of the respective portions of the servo piston housing portion 1, and the sliding portion of the servo piston 2 The outer diameter of the sliding surface of 2C is set to the maximum diameter (outer diameter of dimension X) among the outer diameters of the servo piston 2.

  The inner diameter of the dimension Y of the pressure chambers 6A and 6B forming the gap of the piston housing part 1 in which the springs 3A and 3B are arranged is set larger than the inner diameter of the dimension X of the cylinder part 1A of the servo piston housing part 1. It is. The outer diameters of the springs 3A and 3B are set larger than the outer diameter of the dimension X of the sliding portion 2C of the servo piston 2.

  Further, the pressure chambers 6A and 6B positioned on the axially outer sides of both end faces 2A and 2B of the sliding portion 2C of the servo piston 2 are subjected to a pair of spring seats 4A and 5A and a force of the spring 3B. A pair of spring seats 4B and 5B to be received are arranged.

  A pair of spring seats 4A, 5A in which shaft portions 2D, 2E having a diameter smaller than the outer diameter of the sliding portion 2C are arranged in the pressure chambers 6A, 6B and another pair of springs are provided on both side portions of the servo piston 2. The seats 4B and 5B are extended so as to be inserted therethrough. A nut 7A for restricting the movement of the spring seat 4A is screwed to the shaft portion 2D of the servo piston 2, and a nut 7B for restricting the movement of the spring seat 4B is screwed to the shaft portion 2E. .

Further, as shown in FIG. 1, in the reference example , the distance between the edge portions 2F and 2G forming both end faces 2A and 2B of the sliding portion 2C of the servo piston 2 is a, and the cylinder portion 1A of the servo piston storage portion 1 is The length dimension is b, the width of the opening hole 9 to the pump casing (not shown) is c, the stroke of the servo piston 2 in the left-right direction is s, and the edge portion 2F (2G on one side of the sliding portion 2C of the servo piston 2 is 2G. ) To the end face 1C (1D) of the cylinder part 1A of the servo piston housing part 1 {= (ba) / 2}, and the shortest of the overlapping parts of the sliding surfaces of the cylinder part 1A and the servo piston 2 When the length is R {= (ac) / 2},
L> s (1)
R> s (2)
The relationship is set.

In the reference example , when the tilt control pressure is supplied to the pressure chamber 6A, for example, from the neutral state shown in FIG. 1, the servo piston 2 moves rightward against the spring force of the springs 3A and 3B as shown in FIG. Stroke to. At this time, the displacement of the spring seat 5A in the sliding direction is restricted by the step portion 1B which is a stop portion of the servo piston storage portion 1, and the spring seat 4A is screwed to the shaft portion 2D of the servo piston 2 which is the stop portion. The displacement in the direction opposite to the sliding direction is restricted by the nut 7A, and the displacement of the spring seat 5B in the direction opposite to the sliding direction is restricted by the end surface 2B of the sliding portion 2C of the servo piston 2. The displacement of the spring seat 4B in the sliding direction is restricted by the cover plate 8B. As a result, the springs 3A and 3B are compressed.

  As described above, when the servo piston 2 strokes, the swash plate tilts as described above via a slider (not shown) housed in the slider housing portion 2H of the servo piston 2 and a pin provided on the swash plate (not shown). The displacement volume is changed.

According to the reference example configured as described above, since the servo piston 2 is composed of a single member including the sliding portion 2C, there is no fear of an axial shift in the sliding portion 2C, and excellent slidability can be ensured. Thereby, the reliability with respect to the apparatus can be improved.

  Further, the springs 3A and 3B for urging the servo piston 2 are arranged in the pressure chambers 6A and 6B located outside the both end surfaces 2A and 2B of the sliding portion 2C of the servo piston 2 in the axial direction. The outer diameters of these springs 3A and 3B can be set without being restricted by the outer diameter of the dimension X of the sliding portion 2C of the servo piston 2. Accordingly, the outer diameters of the springs 3A and 3B can be set as large as possible, and thereby the spring force of the springs 3A and 3B can be set strongly without causing an increase in the size of the device, thereby realizing a reduction in size of the device. To contribute.

  Further, the inner diameter of the sliding surface of the cylinder portion 1A of the servo piston storage portion 1 is set to the minimum diameter among the inner diameters of the respective portions of the servo piston storage portion 1, and the sliding portion 2C of the servo piston 2 is slid. Since the outer diameter of the dimension X of the moving surface is set to the maximum diameter among the outer diameters of the respective parts of the servo piston 2, the servo piston 2 consisting of one individual can be easily accommodated in the piston accommodating portion 1. it can.

  Further, the distance a between the edge portions 2F and 2G of both end faces 2A and 2B of the sliding portion 2C of the servo piston 2, the length b of the cylinder portion 1A of the servo piston storage portion 1, and an opening hole of a pump casing (not shown). Since the relationship between the width c of 9 and the stroke s of the servo piston 2 is set to the relationship of the above-described formulas (1) and (2), the servo piston 2 can be operated even if the servo piston 2 is full stroked. The two edge portions 2F and 2G are not detached from the sliding surface of the cylinder portion 1A, and stable sliding of the servo piston 2 can be realized.

FIG. 3 is a cross-sectional view of an essential part showing a state when the servo piston is neutral in one embodiment of the variable displacement hydraulic rotating machine according to the present invention. In the above-described reference example , the stroke amount in the left-right direction of the servo piston 2 is equal, but in this embodiment, the stroke amount in the left direction is different from s1, and the stroke amount in the right direction is different from s2. Yes. Further, the width d1 + d2 of the gap 10 is made larger than the width c of the opening hole 9 of the pump casing, and the sliding portion 2C of the servo piston 2 from the center of the servo piston 2 in a state where the servo piston 2 is in the neutral position. The length a1 to the edge 2F on one side and the length a2 to the edge 2G on the other side are different from each other, and the length from the center of the servo piston 2 to one end face 1C of the sliding surface of the cylinder portion 1A. The length b2 from b1 to the other end face 1D is different.

  And in this embodiment, it sets beforehand so that it may become the relationship of following (3)-(6) Formula.

L1 (= b1-a1)> s1 (3)
R2 (= a2-d2)> s1 (4)
L2 (= b2-a2)> s2 (5)
R1 (= a1-d1)> s2 (6)
That is, the length L1 (L2) from the edge portion 2F (2G) of the sliding portion 2C of the servo piston 2 to the end surface 1C (1D) of the sliding surface of the cylinder portion 1A of the servo piston storage portion 1 is the stroke in the same direction. It is set larger than the amount s1 (s2), and further, the shortest length R1 (R2) of the overlapping portion of the sliding surfaces of the cylinder portion 1A and the servo piston 2 is set larger than the stroke amount s2 (s1) in the other direction. is doing.

Even in the present embodiment configured as described above, when the servo piston 2 has a full stroke, the edge portions 2F and 2G of the servo piston 2 are not detached from the sliding surface of the cylinder portion 1A. Thus, it is possible to realize a stable sliding, and the same effect as in the reference example can be obtained.

It is principal part sectional drawing which shows the state at the time of the servo piston neutrality in the reference example of the variable capacity | capacitance type swash plate type hydraulic rotating machine which the present inventors devised previously . It is principal part sectional drawing which shows the state at the time of the servo piston sliding of the reference example shown in FIG. It is principal part sectional drawing which shows the state at the time of the servo piston neutrality in one Embodiment of the variable capacity type hydraulic rotating machine which concerns on this invention. It is sectional drawing which shows the conventional variable capacity type | mold swash plate type hydraulic rotating machine.

DESCRIPTION OF SYMBOLS 1 Servo piston accommodating part 1A Cylinder part 1B Step part 1C End surface 1D End surface 2 Servo piston 2A End surface 2B End surface 2C Sliding part 2D Axis part 2E Axis part 2F Edge part 2G Edge part 2H Slider accommodating part 3A Spring 3B Spring 4A Spring seat 4B Spring seat 5A Spring seat 5B Spring seat 6A Pressure chamber (gap)
6B Pressure chamber (void)
7A nut 7B nut 8A lid plate 8B lid plate 9 opening hole

Claims (4)

Variable displacement swash plate type hydraulic rotation equipped with a servo piston that tilts the swash plate that determines the displacement volume, a servo piston housing part that houses the servo piston, and a spring that biases the servo piston to a neutral position In the machine
The servo piston is composed of one piece including the sliding part,
At each of the axially outer positions of both end faces of the sliding part, the spring and a pair of spring seats that are arranged so as to sandwich these springs and receive the force of the spring are arranged,
The inner diameter of the sliding surface of the cylinder part of the servo piston storage part is set to the minimum diameter among the inner diameters of the parts of the servo piston storage part,
While setting the outer diameter of the sliding surface of the sliding portion of the servo piston to the maximum diameter of the outer diameter of each portion of the servo piston ,
The stroke amount to one side of the servo piston is s1, the stroke amount to the other is s2,
When the servo piston is in the neutral position,
Of the length from the end surface of the sliding portion of the servo piston to the end surface of the cylinder portion of the servo piston housing portion, the length on one side is L1, the length on the other side is L2,
When the shortest length on one side of the overlapping portions of the sliding surfaces of the cylinder part and the servo piston is R1, and the shortest length on the other side is R2,
L1> s1, R2> s1, L2> s2, R1> s2 in advance
A variable capacity swash plate type hydraulic rotating machine characterized in that In the invention of claim 1,
A variable capacity swash plate type hydraulic rotating machine characterized in that all of the springs are configured to bias the servo piston toward the neutral position. In the invention of claim 2,
A variable capacity swash plate type hydraulic rotating machine, wherein the spring is a compression spring. In the invention of claim 2,
A variable capacity swash plate type hydraulic rotating machine characterized in that an inner diameter of a gap portion of the servo piston housing portion provided with the spring is set larger than the inner diameter of the sliding surface of the cylinder portion.

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